radiator in the back idea

I'm planning to place the radiator in the back of my 1973 1303 beetle.
See details:
http://home.tiscali.nl/~gmolhoek/alfa/radiator/index.htm

Tell me what you think of it.

I seriously doubt that you will be able to get enough cross-section area of ducting up to rid the waste heat of a 200kW engine. The EJ20T conversion I was involved in seems marginal - and that is with the rads and two thermo fans up front

The ducting from under the car will also be expensive and vulnerable

Another factor - more weight, more rearward and higher... not real flash for handling.

BUT if you are willing to cut sheet, try it and see. If it doesn't work, it will be easy to rectify

I've already done that, and have been running that set-up for over 2 years.

Perhaps you should read this post;
http://forums.aussieveedubbers.com/viewthread.php?tid=40641

Some pictures aren't working as my site is changing servers

Baja Wes wrote:I've already done that, and have been running that set-up for over 2 years.

Yep and it is in a Baja with heaps of air flow and still gets hot on the highway... maybe scoops will help but bug is much lower to the ground and doesn't see anywhere near as much air flow as a baja.

Not saying it won't work but I think you will have to cut a hell of a lot of sheet metal out to make it work.

you can make anything work if you want, but why reinvent the wheel?

the rad will work better at the front, even VW did this when they turned Type2s into water pumpers. And this is coming from a man with a rear mount rad. 😉

As much as I hate to say it, I'm sure you could make it work for a small engine like this if you are really against cutting up front. If you look at my speedster cooling system from the Alfa days it had a mini radiator either side of the bellhousing and that cooled fine but was at its limits with 120bhp. Depending on the hight that you mount them you may be too reliant on the electric fans which I would NOT want in any situation. One of the better rear rads I have seen is the Bennetton F1 styled wasserboxer bug on design 90's which had it at the upright position where the firewall was and fully enclosed with rear quarter panel Remmele style ducts...

Rich

Gentlemen, thank you for your replies.

I'm going to give this setup a try.

gerrelt. talk to 72rsbug about this. i know i have and his ej20tt is having cooling problems and he said to me that he is doubting the functionality of the rear radiator setup. i think he is starting on a front radiator setup in the spare wheel well.

i would go something that has been proven as it is not worth the money nor the time to do the install just to find the motor runs hot or gets damaged.

it is an alfa motor you are using yeah?

i dont know how the alfa 4cyls run but mum has a 156 with the 2.5l v6 and it runs quite hot considering.

Anthony

mine gets hot on the highway because I currently have no scoops at all.

I hoped the low pressure behind the car would suck the air through. It works fine up to 100kph. Over that and the air flowing under the car is going so fast it seperates at the rear torsion bars and creates a low pressure under the radiator. Essentially the air is going to fast for the flow to curve up under the car and turn into the radiator.

I also think when this occurs because the radiator is in a low pressure pocket, but the cooling fans are going, it just causes the air coming out of the radiator to turn back around under the radiator and recirculate. A plate at the rear of the radiator extending down around the gearbox would fix the recirculation.

I am sure the lack of air flow at 100kph+ will be fixed with a couple of scoops mounted off the trailing arms / torsion bars. Don't bother with pipe style ducts, they will be too small and won't provide enough air. You need a plate as wide as possible.

Your also going to have to cut out alot more than you have shown for the radiator. You want to cut out the whole parcel area and put a curved cover in there, so the air flow into and through the radiator is smooth.

I agree with wes on the scoop front. Pipes are too small. You need a ducting that is at least 1/3 the surface area of the radiator if you are going to get enough air. Ricola clued me up on this when I made my scoop.

Secondly, I've read the reply you got from the guy on the shopforums and looked at his pinto/bug conversion. His radiator had the fan running all the time. This a bad idea coz firstly, it drains a lot of current from your alternator and secondly, if the fan dies, the motor cooks very quickly. And factory fans are not designed to run constantly.

Another thing to consider is that you need COOL air getting the rad. This means scooping air from the outside of the car into the rad box and then getting rid of the hot air effectively when it's done it's job. Making a shroud for your fan will help it work better too.

Look at my write up on what I did for mine...

http://www.geocities.com/peterwood734/buggyproject/buggyproject10.html

I have since discovered that the rad gets so much air from the scoop that the fans hardly come on the freeway...that and the temp maxes out at 85deg, even on hot days at over 110Km/h. This is ideal.

ARR NO NEED FOR ANY MORE DISCUSSION ON THE MATTER AS BUGGY BRAD ( IM THE EXPERT JUST ASK ME I BROUGHT A VW SHOP) HAS SPOKEN... :sandrine

And as per usual VDUBYA has offered another futile attempt at being funny. If only that little brain of yours could control your rogue fingers from typing.....

Back to the topic...there have been hardly any problems with front radiator setups, yet I have heard of numerous cooling probs with the rear setup. It is really busy back there and I am finding running a 3.5 inch flexible tube to my air filter a squeeze.

Good luck whatever you choose...copy one that works!

Matt

Im for Brad with evidence than vdubya with vitriol

koolkarmakombi wrote:Im for Brad with evidence

Well Buggy Brad's evidence is actually my car, so maybe you should be listening to the owner since everything Brad knows is 2nd hand information of what I have told him (not talking anything away from Brad's expanse of knowledge, we are good friends afterall 🙂 ).

My rear radiator set-up runs hot at highway speeds+ only. This is because it currently has no scoop at all. It seems pretty logical that the scoop will give it the air flow it needs. The engine also works harder on the highway being an unaerodynamic Baja and all.

A front radiator hidden behind the body work would also probably get hot too unless you add some sort of scoop to kick the air up.

Having said all that, The front radiator set-up is easier to pull off successfully. In a beetle I would put the radiator at the front for the easier cooling, and better weight distribution (you want more at the front to counter the extra engine weight at the rear).

I went rear on the Baja because offroad you want all the weight over the drive wheels and can live with some understeer. The rear radiator is also more protected from damage from the ground and stones from the car in front.

VDubya wrote:ARR NO NEED FOR ANY MORE DISCUSSION ON THE MATTER AS BUGGY BRAD ( IM THE EXPERT JUST ASK ME I BROUGHT A VW SHOP) HAS SPOKEN... :sandrine

um yeah, ok, right whateva. :o

Have you got that out of your system? coz if you have maybe you'd like to help the discussion now. 😉

I have found with my experience in regards to a supercharged Holden 6 cylinder motor, that airflow is not the only factor. I had a 3 core radiator with two big thermo's on it and at higway speed was the only time it got hotter, due to the extra hp it was using to go that fast.

Physics is a science with laws that cannot be changed and in this circumstance the radiator was simply not big enough. The heat generated from the hp was not able to be removed from the fins of the radiator, no matter how much air was put through it. This is a front mounted radiator in a Holden dont forget.

The solution was to provide more physical surface area to remove the heat. This I did with a performance radiator designed for 350 Chev install into EH. Seeing as my motor was now putting out similar hp figures as a warm 350, it seemed logical.

In the end the problem was solved and it runs sweet as.

My opinion the rear setup will work if you have the required amount of air and a large enough radiator. You can get custom units made by companies like Aussie Desert Cooler.

The other EH I have has twin 9" thermo fans on it which are awesome. I got them from the USA with an air conditioning condensor setup, and I recommend 2 x 10" rather than a single 12". 2x12" fans would be even better.

if I get time at work I will do some quick calc's for you guys to show you how the air flows.

So you start by quickly modelling the rear of a beetle (baja style), gearbox, torsion bar, axle and suby motor in CAD. This was a real quick job. You only want a cross-section, no wheels or anything.

then you put it into a CFD program (computational fluid dynamics).

Below is a simulation of it travelling at 100kph. notice the air doesn't want to flow through the radiator area by itself at all. This is what I am currently running in my car, so no surprise it gets hot on the highway.

When I get time I will model 100kph with scoops, and some slower speeds.

I'll probably get shot for this, but perhaps run a whale tail and have the radiator under the wing? Is that possible? or is it too much weight?

works for Reub's car...or is it just the intercooler in the back?

Wes, what program did you use to get that? I'd be interested in running a couple of ideas through it...
Rich

Cool! Wes is getting scientific! That's a really usefull picture. I like where this discussion is going.

But, if I put the scoop in your picture where I planned it, it would be right in the air-flow. Like this:



I would be really interested in that picture of the airflow with a scoop, Wes!

Great replies!

ricola wrote:Wes, what program did you use to get that? I'd be interested in running a couple of ideas through it...
Rich

It's CFX, related to ANSYS 10. The licence for both is over $50,000. If you draw the geometry of your idea I could probably do the run for you. Drawing the thing is the slow part.

What I drew was actually 3D, but I only posted the 2D screen shot. I have the gearbox modelled (roughly) and engine varies in height to roughly model a boxer engine. I'll try to add a scoop and show some more stuff next week if I get a chance.

I should have changed the scale on the side. It is showing 0 to 44.59m/s which is 0 to 160kph. The red is the 160kph, the yellow is 120kph, the lime green is about 100kph, and the green is 80kph.

So on the left I set the air velocity to 100kph (the lime green). The air is seperating from the rear window area and causing a large low pressure behind the car. This is pulling the air under the car faster than 100kph (mainly 120kph). Under the sump is the smallest area so this is where it hits the highest velocity of 160 or so kph. All pretty bad for aerodynamics.

Some air is going up through the gearbox area, hitting the front face of the engine and making it's way over the top. But in the radiator area the air flow is much slower, around 40kph (cyan). You can see dead pockets of flow behind the axles and torsion bars (blue). My car has even more of these because it also has trailing arms causing dead pockets.

Rueb has the intercoolers in the tail.

Matt

Sorry Pete you are totally right, in an effort to make a constructive coment to the post I have been preparing a air flow diagram just like our technical guru Wes. Unfortantly I can not post it as yet as the kids are hogging the coloured crayons.

VDubya wrote:ARR NO NEED FOR ANY MORE DISCUSSION ON THE MATTER AS BUGGY BRAD ( IM THE EXPERT JUST ASK ME I BROUGHT A VW SHOP) HAS SPOKEN... :sandrine

Ha Ha ha ;

Brad and wes the VW legends
Great Post VDubya

are y guys having a lovers tiff ??

I wouldn't say me and Brad are VW legends. However we do know a thing or two about engine conversions, and I'm sure Brad has already done more conversions than nearly everyone on this forum (we do have a few good experienced guys here) and tried a lot of different theories in the process.

I only post in posts that I know something about. Unlike some people on this forum that post in posts they pretend to know something about, or just can't help themselves from wanting to sound like they know something.

How about the pessimists in this post go elsewhere. This is a good thread with some good info. I don't want to have to moderate peoples posts.

What we need to remember COLD AIR is needed to the RAD.Dragging air from under the car on a hot summers day,a hot road and air being dragged to the RAD to the rear of the car is not very effective.....COLD AIR sits higher.Look at setting some NACA ducts from the side or top of car.A RAD up front is capable working better and attracting COLDER AIR and practicle.......Just to note Brad & Baja Wes know ther stuff ...JVLRacing

true, the air low near the road is hot. But you have the same problems with a front radiator in a beetle unless you cut holes in the bonnet.

Again from this perspective the rear radiator is more suited to a baja than a lowered beetle, as you get a heap more air under the car so the bulk of it isn't so hot.

So if you set some air scoops under the car,at the end of the tubes set some electric fans that will draw the air colder to the rad.That possible make the air cooler for a baja.Do you think that would work?....JVL

I'm sure Brad has already done more conversions than nearly everyone on this forum

Really? The only ones were seeing are the same ones other shops have been doing for 10 years.

Took my Caravelle elsewhere and got an extra two cylinders without the smart ass comments I was getting from the other shops I asked about doing it.

Really? The only ones were seeing are the same ones other shops have been doing for 10 years.

I said "on this forum".

I haven't seen any of the other shops on this forum, and if they were their advise would be welcome. We have open minds.

Besides, Brad has been involved with two KLZE engine transplants, I haven't seen a shop do one of those before. The EJ22's are just the sensible easier engine conversion they do more often.

Brad has a unique personality. If you ask him a stupid question you will get a stupid answer. Judging by your non-constructive comments so far on this post I can only assume the smart ass comments were self inflicted.

If you care to discuss this further you can u2u me. Anymore non-constructive posts in this thread will be deleted.

Baja Wes wrote:Brad has a unique personality. If you ask him a stupid question you will get a stupid answer.

Brad has been very helpful with my EJ22 conversion in the bay, and. Even though he has done a heap of them, he was still very open to my thoughts. He is very receptive to receptive people.

To keep things on topic, I think the radiator in the back hidden away is a great idea. It would be such a great point of interest to the conversion.

this may be a completely looped out idea...but would it be possible to "mid mount" two smaller radiators (one on each side) under where the back seats used to go without losing too much strength in the pan?

was thinking this as it can be hidden away under the some stereo housing .etc

just an idea.

Anthony

my radiator is above the gearbox, and I still have the rear seat and a 12" sub behind it. It's just s very shallow sub box.

Thought I'd tell you something interesting I noticed while driving on the weekend.

On saturday on the way home from the cruise (The entrance to Sydney) i drove the buggy at 110km/h WITHOUT the side screens on for the first time. The engine ran on average 5deg hotter. I can only put this down to the drivers side screen normally channeling the cool air toward the scoop. I am not sure about the specifics of the aerodynamics of the car, but I was surprised to see such a difference, keepng in mind this was up and down all the major hills along the F3.

I spose the moral to the story is that small things like this can make a big difference when the car is under load at speed. So where I thought i had the rear rad setup completely sorted on my buggy, I'm now inclined to believe It might be up for more development...not sure how, that's all.

BTW, can people please keep the bonehead comments and personal insults out of the post? If I wanted to hear those I'd catch a train and listen to the local Junkies argue like three year olds.



[ Edited on 17-10-2005 by pete wood ]

I don't want to clean up the post unless I have to, as it seems to cause errors in the database occasionally.

So I didn't like my last model, and decided I needed the front of the car. I also added part of a decklid. I left the top of the decklid open, simulating really good vents in the top half. The model is a slice of the car beside the gearbox, over the axle area. The car is a real rough guess as I don't have any dimensions of a beetle handy 🙂

This is a streamline diagram. It shows where all the air flows.

you can also do a vector plot which shows air direction and speed at various points of interest. You can see without scoops the radiator area is in a dead air pocket, as you'd expect. You can also see the flat VW windscreen is quite bad aerodynamically.

then I added a small scoop. It is a plate that sits 50mm below the floor pan and bends up to point above the axle. You can see this makes quite a big difference.

The problem is australia is that scoop legally must be 100mm off the ground. No problem in a Baja, but a problem in a street beetle.

Good effort Wes - I remeber what it was like playing with ANSYS through uni, must be fun to have tools like that at your disposal. Just like I appreciate having a full machine shop around when I want a foreigner I guess.....

I think your rear mounted radiator is definetely a workable solution. I dont think its the ideal location, but given that you are planning on running a 1400cc Alfa motor instead of a 2L turbo or a 2.5L v6 the heat load (and consequently cooling required) is not so large.

You will most definetely need a good scoop like Wes's diagrams show - you will also need the thermo fans so that air is moving over the core whilst you are standing still. There is really quite a bit of room under the car there so you should be able to put something quite neat together - think aluminium sheet or fibreglass I guess.

I look forward to seeing your unique ride - it is the fact that we are all different and have different ideas that pushes us to innovate. Innovation is the mother of progress, so...... be different and find a new solution !

Wes, If I sent you a pics of my car could you do me a diagram too?

the hard part is drawing it Pete. Drawing from a photo is very difficult.

If you can drawn a section of your car in 2D CAD then I could do a run easy enough. 3D cad is preferable.

If you give me a scale drawing (even a scan of a hand drawing) I can stick it in CAD and quickly trace around it possibly.

Your car no doubt would have a large low pressure dead velocity zone from your windscreen backwards.

would doing an outline in paintbox suffice? I ain't got CAD and it's been ova a decade since I used it. 🙁

I used Cad to design my chassis from my engineer (Long while ago)Deffently a learning point....Wes these diagrams deffently only good for a Baja because of the escape air point of veiw is that right?.....JVLRacing

[ Edited on 17/10/2005 by jvl054 ]

Talked to the owner of this oval with ej 22, finally got his telephone number! He is driving his beetle with the radiator in the back, just like you want. He is using a scoop under the car and his decklid can be opend by a small hydralic pump. He says it works fine even on 35 degree celcius days. Without the open decklid it worked just up to 25 degrees celsius.

jvl054 wrote:Wes these diagrams deffently only good for a Baja because of the escape air point of veiw is that right?.....JVLRacing

The model is only a quick very rough model to basically show what happens and what the flow looks like.

I tried to model something that is actually more like a beetle with heaps and heaps of louvres pressed into the top section of the decklid, and it propped open slightly. This allows air through the top section.

In a rough model you don't bother modelling all the individual louvres, because it would take forever and it makes the CFD model very complicated and slow to run and solve.

Pete, in you draw it to scale in paint then maybe I could give something a quick go.

Wow, this post is getting better and better! Thanks for the encouragement guys, and Wes, thanks for the great pictures, I saved them on my computer. This is exactly the stuff I was looking for, brilliant! :thumb:thumb:thumb

I wish I would have known about this website, and especially this thread, before I started my own rear mounted Rad setup. Thanks for the tip Gerrlett.

Here are a couple of pics showing my build so far. This is of course on a Baja, but the rear parcel area is considerably different than most sedans due to my sheetmetal work and rollcage. I knew I would have to isolate the Radiator in ductwork to contain and direct the airflow. I did my own "backyward" experimenting with a leaf blower and a piece of string....haha I found a decent amount of air movement just over the gearbox so that is why I decided on that location. I was however, unsure of the airflow being sufficient. That graph you posted Wes was worth the price of admission. Showing how a simple wing will create that much additonal airflow makes me very happy. Take a look at my work in progress and let me know what you think.

SHMO

trimmed parcel area

radiator framework

radiator frame/ductwork (photoshop)

frame installed in car

installed with ducting (photshop)

SHMO wrote:I wish I would have known about this website, and especially this thread, before I started my own rear mounted Rad setup. Thanks for the tip Gerrlett.

Here are a couple of pics showing my build so far. This is of course on a Baja, but the rear parcel area is considerably different than most sedans due to my sheetmetal work and rollcage. I knew I would have to isolate the Radiator in ductwork to contain and direct the airflow. I did my own "backyward" experimenting with a leaf blower and a piece of string....haha I found a decent amount of air movement just over the gearbox so that is why I decided on that location. I was however, unsure of the airflow being sufficient. That graph you posted Wes was worth the price of admission. Showing how a simple wing will create that much additonal airflow makes me very happy. Take a look at my work in progress and let me know what you think.

SHMO

trimmed parcel area

radiator framework

radiator frame/ductwork (photoshop)

frame installed in car

installed with ducting (photshop)

Welcome SHMO, nice work.Deffently seeing Wes Baja diagrams and your pics of fabrication tells many words.:thumb:thumbJVLRacing

shmo, it's a pity my website is currently not working (still waiting for the file transfer to the new server) as I have some good photo's of my car.

You will see our cars are very similar in set-up.

As you can see here, it all fits behind my back seat. This is a bad photo because it's after an offroad trip and everything is covered in dirt.

This shows the view through the hatch inside the car. You need to insulate the hatch really well, as huge amounts of heat will try to radiator into the car.
http://forums.aussieveedubbers.com/viewthread.php?action=attachment&tid=40641&pid=380538&aid=43637

This is a pic with the hatch install, back seat in place, and 12" sub and speaker box mounted on top. You'd never know a radiator is in there.
http://forums.aussieveedubbers.com/viewthread.php?action=attachment&tid=40641&pid=380426&aid=43627

I also marked up the top photo to show what everything is.

[ Edited on 19-10-2005 by Baja Wes ]

also download this pdf;
http://offroadvw.net/bajawes/Big%20Bad%20Baja%20-%20Part%202.pdf

It is only ~830kB. It has some ok pics of my engine and radiator set-up.

and another useful pic of the rear of my car

Wes,

your setup is fairly similiar to mine. However, your radiator is mounted considerably flatter. One question, is there anything stopping the ariflow from going around the sides of your radiator? Actually I have several questions now that I think about it...haha What size is your radiator? What kind of CFM's are your fans pulling? And the ultimate question, how well does your setup work?

I really wish I could see more of your car to see how exactly everything was done.

SHMO

Oh nice,

I guess I should have just shut up and waited for a second. Thanx for the extra pics....lol

SHMO

if you go to http://forums.aussieveedubbers.com/viewthread.php?tid=40641&page=2

you will see I discuss my experiences with that set-up.

It's a standard japanese 1992 mazda MX6 radiator, fans, and engine. I figure they were made for each other so I'd keep using them together.

Basically it is fine up to 60mph. Over that and it starts to get hot. It's quite obvious all it needs is a scoop, which I don't have.

Yes I have some side pieces between the radiator and the body. I just need something from the rear of the radiator down, and a scoop.

Wes,

I have checked out your car as much as possible. It looks to be very well thought out. I can't wait for your website to get back online so I can see more of it.

I was wondering. What vehicle did you steal that coolant surge tank from? It's a very clean and compact looking little unit. Also, is there any reason you chose to use a surge tank as opposed to a simple inline filler neck with your setup?

This is good info for anyone doing a radiator setup as well. To avoid air pockets, you need to have the filler in the highest possible area of the coolant level. Otherwise, you will need to use a surge tank to allow the air to escape the system.

SHMO

It just dawned on me. If anyone is curious about my buildup, you can view the breakdown of my car here.

SHMO's Baja

I posted lots of pics showing most of the cars details.

SHMO

SHMO, my surge tank is also from the MX6. I bought an MX6 front cut (which you can see in picture of in the pdf link that I posted above) and basically used everything from the front cut. Wiring loom, ECU, cooling system, everything I could. I hope to get the climate control in my car in the next couple of months too.

very nice Baja SHMO,

Wes, I believe you have some competition :P

I don't think there's any competition, SMHO's baja is clearly much better than mine. Kick ass suspension, and very nice attention to detail. The only thing I don't like is the choice of wheel rims. You'd have trouble getting that thing registered in Australia though.

Very nice work indeed SMHO.



[ Edited on 20-10-2005 by Baja Wes ]

Yep,

I would have to agree about the wheels. They were simply the cheapest/strongest/shiniest wheels I could find when I first started the project. I am working on replacments as we speak.

Registering my car in Australia probably wouldn't fly. it is not even technically legal here. Luckily where I live we do not have inspections, and it started out as a standard run of the mill beetle. I just continued to pay the licensing as I built it. If I lived in California it would be a whole different story. I am sure I will eventually run into problems with law enforcement and have to take it off the streets. But, for the most part I built it to use in Baja Mexico. You can do anything you want down there...haha

Wes, don't cut your car short. I have checked it out. That thing is nice! Very well done. I plan on picking your brain a lot regarding that car (if you don't mind).

SHMO

Cool thread good to see someone backing up what they have to say with some quality graphics.

A question though ... in the two Baja's shown I can see how the air gets out the back after going through the radiator, how do you think it will go in a Beetle, with decklid on ? If you get the flow in will it be able to get out ??

Some might disagree with me, but in a standard beetle I would definately mount the rad up front.

SHMO

I would probably put it in the front in a beetle too.

A beetle would need a decklid with lots of holes of louvres in the top halve of it, or a decklid propped open. Or a combination of both.

Wes, would a short spoiler/diffuser across the back of the bonnet help with the poor aerodynamics of the flat screen?
In regards to the airflow to the radiator your calculations are looking at pressure differences, but would not a major aspect of radiator requirements be air volume? ie, high pressure through a small but wide scoop under the car, opening to the large radiator area to create lower pressure but higher volume of air movement through the radiator?

my calculations are not based on pressure. They are based on flow. I created an air fluid domain with an inlet boundary condition of 100kph air on the left, and an outlet boundary condition of 100kph air on the right. What happens in between is all calculated. The diagrams I have shown are air velocity, I haven't plotted any pressure contour maps. The pressure contour maps aren't that exciting. The screenshots I posted show high air flow through the radiator area.

Wes..
One of my DC's is currently getting some body treatment by Brendan up your way.. All this talk of airflow has got me thinking about how i will cool the planned 1uzfe V8.. While Brendan is flaring the back guards out, perhaps I should be thinking of working an airflow duct on each side in front of guard, testarossa style!!..
Not sure how this would be fabricated but with a large capacity duct on both sides flowing air onto a mid mounted radiator set up (maybe a rad opposed either side).. I am sure that would provide me a cooling solution (not to mention a subtle styling).. What do you think?.. Rob
PS: I'm not looking anymore.. got 3 DC projects.. dave becker is rebuilding a 1916 in the one in SYD, Brendan is creating a monster in BNE and I have another in Melbourne that is waiting for a plan..
Cheers

Baja Wes wrote:I wouldn't say me and Brad are VW legends. However we do know a thing or two about engine conversions, and I'm sure Brad has already done more conversions than nearly everyone on this forum (we do have a few good experienced guys here) and tried a lot of different theories in the process.

I only post in posts that I know something about. Unlike some people on this forum that post in posts they pretend to know something about, or just can't help themselves from wanting to sound like they know something.

How about the pessimists in this post go elsewhere. This is a good thread with some good info. I don't want to have to moderate peoples posts.

Sten, you should talk to Kimm at Indian before you do anything else. His DC is the ultimate setup for cooling. it runs cool at nearly 200km/h.

Thanks Pete.. I've had a look at Kimm Garlands setup.. Was a couple of years ago and I had forgotten some of what he had done.. From memory there are some things he would do differently but overall, a great package.. At this stage, while fabrication is happening in sunny QLD, I thought the ducts in front of the guards need to be decided on.. Otherwise I will need to retrofit which I want to avoid.. Those big ducts on Kimm's dual cab look great.. I would want to blend them in somehow with flared guards, baja style!.. This image borrows Kimms setup and show the challenge on a baja bus.. I am sure with some creative thinking it can be done and made to look very good! Anycase.. food for thought..

pete wood wrote:Sten, you should talk to Kimm at Indian before you do anything else. His DC is the ultimate setup for cooling. it runs cool at nearly 200km/h.

I just thought I'd give people an update on my radiator set-up.

We have just had the hottest December on record here in Brisbane, and this has highlighted the weakness of my radiator set-up. One particularly hilly road with a very long steep 80kph cause the temp guage to start rising, and anywhere doing 100kph or above would cause it to climb all the way to HOT.

So I decided I had to pull my finger out and develop the scoop idea.

Hi

The weather we’ve been having will test any cooling system, it will be interesting to see if your scoop helps Wes.

I wonder how, Jak, boof and Paul are getting on at the moment with their Subaru bugs?

Steve

well i just spent the last week on fraser in this heat.
my car dosnt like the slow crawl through the soft stuff.
it manages to get a litle hot so i shut it down for about 20 minutues aand off i go again .
i think it is due to the fact that i have the radiator in the front of my car and the amount of water being cooled in the radiator is smaller than the amount of water in the line . if you get what i mean

its a ej22 in a baja
and found it does like passing bogged 4wd cars whilst i have my trailer on
terry

[ Edited on 3-1-2006 by subibaja ]

pics terry ..

Subi Baja has a small ass Golf Radiator in the front and I reckon once we duct the air better and give the pickup a greater cross sectional area and thus increase pressure and flow it will cool fine .. then we can add a/c :>



[ Edited on 3-1-2006 by Buggy Brad ]

Steve, you got in too fast 🙂 (my computer wouldn't load the webpage for some reason)

So for a scoop I decided to just test an idea first, and added 1 simple scoop to only 1 side. It is only 130mm wide. I just welded a bit of angle to the front of the shock cannister on the trailing arm, and then bolted a bit of checker plate to it.

I attached it to the arm because then the scoop is always a fixed height off the ground. If I had mounted it on the pan, then the scoop would have gotten very close to the ground when I went over big bumps offroad.

So I took it for a drive today (it was 34, but probably only 30 by the time I hit the road).

First test was the long 80kph hill. I went up it at a little over 80kph in 3rd, no probs. I had noticed the gauge was now usually sitting slightly below half way rather than slightly above half way.

Then I found a fast open stretch of road. I tried 100kph, no problems. I tried 110kph, no problems. I tried 120kph, the gauge started going up but only got to the old slightly above half way position, and then went back to the new slightly below half way position. It keeps doing this, slightly above and slightly below half way.

I figured it is doing this because before the thermos must have been on 100% of the time on their high speed setting (slightly above halfway). Where as now it gets warm and them the low speed setting quickly brings the temp back to below half way, the fan goes off and it gets warm all over again.

So before it was struggling to not overheat with the thermos on high the whole time. Now it stays cool and the thermo switches on and off low speed during extended high speed driving. This is with only a single 130mm wide simple scoop.

So next I just need to add a second scoop (then hopefully the themos will never turn on), and work out how to make the lower part of the scoop less prone to damage offroad. I am thinking I will probably just crawl under and unbolt the scoop for serious offroading.

So the fancy CFD computer modelling was right. All I needed was a simply scoop.

subibaja wrote:my car dosnt like the slow crawl through the soft stuff.
it manages to get a litle hot so i shut it down for about 20 minutues aand off i go again .

mine was the opposite. The thermos would deal with the slow stuff no worries, they just couldn't keep up with pushing a brick like Baja through the air at highway speeds.

Even when my did get hot (all the way to the H) I only needed to pull over and let it idle for 3-5 minutes and then it was fine. The MX6 thermos work really well as they are shrouded and designed for the MX6 radiator. Last time it got that hot was driving over a mountain range full of camping gear in 42 degree heat (after a trip to landcruiser mountain park).

Hi Wes,

well done, i decided a few weeks ago to use the heater for some extra cooling. I don´t need to install a heater to get it registered. My radiator is up front, but i want to get a sleeper look (as little openings for the rad as possible). I couldn´t test the idea because it is winter overhere. The heater is mounted just above the area where you put your scoop! But now with your fine results from a little scoop, i am sure it will work. Thanks man!!

Jörg



[ Edited on 26-3-2006 by subaruboxer ]

Wow, Wes, that's really good news!! It's really great to read about some real live experiences!

This gives me convidence that I might also pull this thing of.

Thanx for sharing your results, I really appreciate it!
:thumb

Good stuff Wes. Mine runs really cool too. It's amazing what a bit of ducting can do, but I'm still inclined to say, stick the radiator up front.

This is how far I am at the moment:



from the back:


I plan on creating air-deflectors under the radiator to make sure ALL the air goes through the radiator.
I will probably make a box out of foam and epoxy to cover the radiator.

Well it's been awhile since I've posted, but I thought I would show some of the progress on my rad install. My plan will be an all aluminum framework to house the rad, and it will serve dual purpose function as ductwork to direct the airflow as well. I can remove the entire structure fairly easily for service work or repairs. I was apprehensive about bolting the aluminum radiator directly to any mounts, so I incorporated a setup in the framework that sandwhiches the rad completely in rubber. It should provide excellent support, even during hard off road use. Here is what it looks like so far.

Trimmed out the rear of the car




Built an aluminum framework to support the rad.



This framework will eventually be sheeted with aluminum and will then act as a ductwork to direct airflow.



This is how the framework will install into the car.



SHMO

Was talking to the Chief on the weekend about a secret project ... and he made a good comment/observation about water power, in relation to his DC.

"When it's run for 10 years with no problems and can still crack 200km/h, then you can say it works, until then, it's a great idea that's being tested".

He was talking at the time about a bus that has changed hands a few times over recent years with 'hot' turbo issues.

He also swears that the box is where the money needs to go to a) not destroy it and b) to give the motor an 'as near to pre-VW' performance experience as possible.

Anyway, don't pretend to understand all this hi-tech stuff, but thought the comment was apt for the time.

I am in awe of what you Sube-boys are doing ... droool

Hey SHMO,

great to see you're back on your project, it's looking good!

This is how far I am with my radiator in the back:

http://home.tiscali.nl/~gmolhoek/alfa/placing_radiator/index.htm

Air-channels from under the car:

http://home.tiscali.nl/~gmolhoek/alfa/air_scoops_channels/index.htm

See the complete story on:

http://www.gerrelt.nl

gerrelt ,

it's looking good. I will be anxious to hear how well it works. It would have been nice to open up the size of the intake in your airbox. A funnel shape would work well in that situation, allowing the incoming air to spread out and cover a larger section of the radiator.

How are you going about directing the airflow into and out of the car/radiator? Will you be incorporating some ductwork of some sort, or just allowing it to come into the airbox and then free flow out into the parcel area?

SHMO

SHMO wrote:it's looking good. I will be anxious to hear how well it works.

Thanx! Yeah, I'm anxious to know too...

It would have been nice to open up the size of the intake in your airbox. A funnel shape would work well in that situation, allowing the incoming air to spread out and cover a larger section of the radiator.

Yeah, I have been thinking about that, but because of the easier way this can be fabricated, I just did it like this. And somehow, without scientific background, I think the airbox shouldnt be too big. I am hoping that the airbox will be presurized by the incoming air, and then the air will spread itself over the radiator.

How are you going about directing the airflow into and out of the car/radiator? Will you be incorporating some ductwork of some sort, or just allowing it to come into the airbox and then free flow out into the parcel area?

After the air passes through the radiator it's just free flow into the (boxed) parcel area, and into the engine compartment. There it will have to pass out of the car through the vents under the rear window, the vents in the rear decklid and the opening behind the licenseplate light and the license plate. And I wil not use a rear decklid rubber seal.
Outgoing warm air won't be much of a problem for you, isn't it? Your car being a Baja.
Man, I was tempted to Baja the rear end of my car... The fitting of the Alfa engine is really close to the rear apron... But it wouldn't make any sense what so ever. It's a super beetle, and there isn't any big wilderness here in Holland to go real offroading (we don't even have real mountains...).

This is a little off topic, but I am ordering some parts for my Engine conversion, and I wondered what some of you have been using for throttle cable setups. I have looked into the morse cables, and even tinkered with the idea of converting a stock Bus cable to work somehow. Just wondering if anyone has a good approach at doing a nice setup for a conversion motor using a GM or similar throttle body. Pics of your installs would be a HUGE help

Thanks,
SHMO

SHMO wrote:This is a little off topic, but I am ordering some parts for my Engine conversion, and I wondered what some of you have been using for throttle cable setups. I have looked into the morse cables, and even tinkered with the idea of converting a stock Bus cable to work somehow. Just wondering if anyone has a good approach at doing a nice setup for a conversion motor using a GM or similar throttle body. Pics of your installs would be a HUGE help

Thanks,
SHMO

Hi SHMO,
I just went to a motorcycle shop and had them make me up a cable. They offered a heavy duty cable with almost any type of ends you want. Their cable housings and cable come in rolls and can be cut to any lenth you need.
One other possibility is a company here in Utah called Six States Distributors. I found out about them after I had already had mine made up, they sell a cable and housing that can bend as tight as a 3" radius and stil work.
Hope this helps,
Bob J.

Now, SHMO got me thinking....
I thought that the radiator would create enough of a restriction so that the airbox would be pressurized. But then I tested this by blowing air through the radiator with my air-compressor. It went right through without much restriction.... Because of that I decided that I indeed needed scoops at the air-outlet. I didn't want to make it too complex, I created one scoop per air-outlet:


[ Edited on 6/4/2006 by gerrelt ]

gerrelt wrote:Now, SHMO got me thinking....
I thought that the radiator would create enough of a restriction so that the airbox would be pressurized.

The amount of pressurization from ram air is very small. At these low pressures the radiator does provide a considerable restriction. With a running vehicle you could check this with manometers on either side of the radiator to see the pressure drop.

George

The amount of pressurization from ram air is very small. At these low pressures the radiator does provide a considerable restriction. With a running vehicle you could check this with manometers on either side of the radiator to see the pressure drop.

George

Ah, that's good to know! I tested with 3 bar with my air-compressor. I will never create 3 bar in my airbox!

gerrelt wrote:

The amount of pressurization from ram air is very small. At these low pressures the radiator does provide a considerable restriction. With a running vehicle you could check this with manometers on either side of the radiator to see the pressure drop.

George

Ah, that's good to know! I tested with 3 bar with my air-compressor. I will never create 3 bar in my airbox!

Well, perhaps if you were reentering from orbit... 🙂

Keep in mind that the pressure drop isn't a bad thing. It is the drop that moves the air from one side of the radiator to the other! No pressure drop = no airflow!

The CFD analysis earlier in this thread was very interesting. I've never seen a Beetle shape run through that sort of analysis. One problem with CFD is that a beetle is a very complex 3-D shape, and the bumpers, fenders, etc. all contribute to turbulance that creates a thick irregular boundary layer around the car, particularly underneath, that doesn't show up with CFD unless you make a very detailed model (and have a lot of processing power to run it!). It would be fun to instrument a few running radiator conversions to see if the actual results are similar to the 2-D simulations.

Another thought pops to mind. A few years back there was a mini-fad of replacement hoods for Beetles that featured Rolls-Royce- and '30s Ford-styled grilles. It would be interesting to see if these grilles could conceal a real radiator setup and still retain the spare tire. The air exit would probably have to be about halfway along the hood, since there is a high pressure region directly in front of the base of the windshield.

George

Well,

I thought I would throw in a few pictures of my engine swap. I haven't done much to it in the last SEVERAL months, but I am back on board and hope to have it up and running in the near future. I'm crossing my fingers this rear radiator idea works out...haha

SHMO

Hey SHMO, that is looking very good! At first I thought that the ecotec engine would look too big in the back of a but, but it fits your bug excellent!

Did you drive it allready?

SHMO wrote:

Aren't you afraid of having a air-lock on that down left coolant hose? It has a high point in it which can't be bled. Would that cause a problem?
I'm asking this, because I got the same problem, I have to route my coolan hoses over the engine to the radiator. The coolant hoses will be a high point in the system (the reservoir will be higher though) from which air can't escape. So I'm thinking a bleeder valve must be fitted or a small tube from the high points to the reservoir.

The thing that makes radiator setups work the best is the relationship between air pressure infront/behind the radiator. If set up correctly the air will be drawn through rather than actually pushed. My intercooler is in the back where it normally sits on a wrx. I scooped the air onto it through the rear gaurds....see pic. It works awesome, although similar to Jak, even with a tiny radiator, my temps hit 88 then the thermo fans come on. This only ever happens in traffic....usually 84-86.

http://www.thesamba.com/vw/forum/album_page.php?pic_id=249708

Matt

gerrelt,
I am not too concerned with the lower rad hose. It doesn't make much of a dip, and I couldn't foresee it trapping much air, if any. But, only time will tell. I have not completed the Ecotec swap yet. There is still a long ways to go. It is just mocked up for the pics.

Boof,
are you running a subie motor in that car? Any pics showing where/how you mounted your radiator?

SHMO

Here are a few udpate pics of my completed (well...almost completed) radiator setup. The back seat still fits in and covers up all of the ugly on the inside. I will insulate the parcel area really well in hopes of keeping the heat out of the interior of the car.










SHMO

Here are a few pics of the (again...ALMOST completed 🤪) business end of the car. I'm getting close boys.










SHMO

My radiator has a hose that dips in almost exactly the same shape and I don't have any air-lock problems.

You will definitely need to insulate that radiator cover as heat will just go straight through it. I used this stuff;
http://www.automotiveinteriors.com/HEAT_SHIELD.htm

I put it on the radiator side of the cover, so the shiny aluminium foil coating faces the radiator and reflects most of the heat. It made a HUGE difference.

I used the foil tape on the edges, it's great stuff. It sticks really well. It's been on for about a year now and hasn't peeled off or anything like that.

That's looking good SHMO.

I came up with a similar design:



I covered the outside with tarboard (stuff specially made for sheetmetal so it won't vibrate) and the inside with sound deadening stuff (the same stuff you can use under the engine lid of a car).



See some more pictures on:
http://home.tiscali.nl/~gmolhoek/alfa/radiator_box/index.htm

Owh, and I got an airscoop done, see this page:

http://home.tiscali.nl/~gmolhoek/alfa/air_scoops_channels/index.htm

Greetings,
Gerrelt.

[ Edited on 22/4/2006 by gerrelt ]

Hey Gerrlet,

I was just looking on your website. (very cool by the way) When I really started looking at your rad mount, I wondered why you decided on a sealed airbox design? Was there a reason you didn't leave the face of the radiator open to natural airflow? Just curious on the theory there.

SHMO

I wondered why you decided on a sealed airbox design? Was there a reason you didn't leave the face of the radiator open to natural airflow? Just curious on the theory there.

I did that because there will not be much natural airflow in that area with my bug. It's not a baja, so the rear is more closed.
That, plus, this way I am more certain that there will be airflow through the radiator. The air can't do anything else but go through the radiator.
And this way only fresh cool air is used to cool it. There is absolutely no way it can catch allready used warm air.

I think I got this idea from the aircooled-setup. In that setup only cool air can be sucked in by the fan, and all the airflow produced by the fan is used to cool the engine. The fresh "cold" air is strictly seperated from the used warm air (by the engine-seal). Only that setup is from top to bottem, and my setup is from bottom to top. Which, in a way, might be more logical because warm air wants to go up.

I hope it will all work out, the theory is nice but.......

Well,

I have finally (for the most part) finished up my engine transplant and rear radiator. I thought I would put my two cents worth in regarding how it worked.

My setup consists of an aftermarket aluminum radiator and a single cooling fan, I think you aussies call them thermos. After completing my engine swap and dealing with some ECU issues, I have finally got a chance to do some actual drive time testing. At an idle my cooling fan will cycle about once every 10-minutes after the engine reaches its operating range. The fan actuates at 215 degrees (101 celcius) and pulls the temps down to 170 degrees (76.6 celcius) before shutting off. This is controlled through the engines ECU. Under a load during normal driving conditions the fan does cycle more often, but by no means does it continually run. I have taken the car up to roughly 100 mph (161 Kph, but in any measurement it's fast for an offroad car on the highway...hehe). I have also sustained speeds of well over 70 mph (113 kph) for extended periods of time. This was done with outside tempretures ranging bewteen 85-92 degrees (29-33 celcius). The engines temps have never climbed past that 215 (101 celcius) degree mark, and the coolant seems to drop almost immediately when the fan begins its cycle. All is good so far.

With that being said, I do have some future plans for the cooling system. I think I will install an additional low CFM fan actuated by a variable speed thermostat. I think this will help to maintain a more constant coolant temp.

Here are a few pics of my (semi) completed swap.

SHMO

Hi

That’s a nice setup. The temp drop your getting is huge and would most likely bring the temp below the thermostat opening temp. I had my temperature controlled by an aftermarket ECU and from memory had fans come on at 95 Celsius and cutout at 90 Celsius.

You might be better of with a non factory fan switch, Davies Craig make them, they are adjustable and only need to have a probe fitted into one of the hoses.

Steve

sweet ride SHMO!

I agree, your thermo temp range seems really big.

Yep,

I totally agree that it ranges too much. That is the primary reason I am considering the second cooling fan.

SHMO

I have my Alfa Romeo conversion running and I am driving it for about 2 months now (and enjoying it very much!!!!:bounce).



I do have cooling problems though. I am "debugging" it at the moment. I very soon discovered that the rear decklid wasn't venting enough and that the radiator fan couldn't suck in enough air through my air channels.
Once I fixed that, the car ran fine in city traffic, but now the challenge is to make it run cool on highway speeds. It still runs hot on higher speeds, probably because of not enough airflow to the radiator. Only the sides of the radiator get airflow. I am planning to create more air ducts.

Read my experiences on my page:
Link to my page, Gerrelt's Garage
Click on the picture, and then click on the link in the bottom of the screen named "Debugging the cooling system".

Hello gerrelt,
nice to see that your beetle is on the road.
I think you have to get more air to the radiator and most important of all is to get the hot air out of the enginebay!
I would put it to a test with an open decklid, screw two little pieces of metall to the hinges at the top of the decklid. This will make a big difference, I am sure.
If you are satisfied with the open decklid, you could build something with a wiper motor to open it, if you don´t like it to be open all the time! But first you have to get more air the radiator. You need some serious shrouding!!

[the ghost of ol'pete] "put the radiator up the fronnnnt..."

seriously.....

Mine's been at the back for about 4 years now and is still ok...

ok, but can I ask you, if you were going to do the whole conversion again, from scratch, with everything you know, would you still put it in the back?

pete wood wrote:[the ghost of ol'pete] "put the radiator up the fronnnnt..."

seriously.....

🙅 No, not yet. I only just began to fine tune it. And besides, putting it up front will bring up other problems. I will loose the place for the spare wheel, I'll have to find a place for the pipes, and, I don't think it will be good on the stock water pump, those long pipes. And bleeding the air out of the system will be more difficult.
The place where I put the radiator was space I wasn't using anyway.

But, if I really can't get it to work, It will go in the front, but I am a "little" hard headed....😁

I learned a lesson this weekend: don't use water pipes without an ridge to hold the hose in place:


I though I converted to a steam engine when that hose came off! 🙄

[ Edited on 13/6/2007 by gerrelt ]

I'm pretty stubborn, so it'd probably go in the back again. 🙂

It has it's advantages. Safer from damage offroad, less water gives quicker heat up in winter (need that heater on a cold morning), mine doesn't need air bleeding at all (it does it itself after the initial fill), it doesn't heat up the fuel tank in summer.

Obviously from a cooling perspective the front is better, but the rear can be acceptable too.

Hi

I don't think that pumping the water to the front is an issue, the T3 Vanagon don't have anything special in the water pump area. The biggest problem that they have is bleeding, as their fill point is way below the top of the radiator. On my WBX bug I had no fill or bleed issues as the fill point was above the radiator top.

Steve

OK, I've come to the conclusion that the rear mounted radiator doesn't completely work in a full body beetle. It works fine while driving around town and on country roads (80 km/h) with the assistant of fans, but at the highway it just doesn't work.
At 120 km/h for a long time the temperature rises over 100 degrees celsius.

But, it was worth a try.

Now, I am thinking about a "hybrid" setup: A small 40x40 cm radiator with fan in the back, and a longer but not higher one 60x20cm in the front connected in series.
The advantage of this setup is, I've allready got the room in the back for the small radiator plus fan, and the front radiator can (hopefully) be placed without cutting a lot in the nose. It will be place where normally the airconditioning condenser is in the american 1303 beetles.

I am thinking of the radiator from a Suzuki Alto in the back and the radiator of a Fiat cinqueciento in the front.

So, what do you guys think?

IMHO, I think it's a bad compromise.
🙅
two identically placed rads, ala F1 car is ok, but 2 in odd places won't be nearly as efficient. It's like having a big radiator up front with 50% of it partially blocked. better to have big air intakes feeding 1 rear mount, or 1 front mounted altogether. Also, consider this. the more complex the pipe work, the harder it will be to bleed. all the extra pipework has to be routed and sealed as well.

Hi

I didn't realize your car was a 1303. Maybe get a space saver spare and mount it on top of your fuel tank and then use the spare wheel area for your radiator.

Bugs@5speed do a low front mount profile radiator for 1302/1303s.

Also do a search on here for users called Jak Rizzo and 1303 and look how they did their front radiator set-up.

As for running hoses front to back, this what I did on my old 1302, the 1.5 inch stainless tubes followed the chassis bolts in the heater channel.

Steve

pete wood wrote:IMHO, I think it's a bad compromise.
🙅
two identically placed rads, ala F1 car is ok, but 2 in odd places won't be nearly as efficient.
It's like having a big radiator up front with 50% of it partially blocked. better to have big air
intakes feeding 1 rear mount, or 1 front mounted altogether.

Most cars on the road have the radiator covered by 50% or even more. If I look at my daily driver (2000 Peugeot 306 1.6 break), almost 75% of the radiator does not get airflow.
Wasn't there a rule mentioned somewhere that 30% of the radiator should get airflow?

pete wood wrote:Also, consider this. the more complex the pipe work, the harder it will be to bleed. all the extra pipework has to be routed and sealed as well.

Yeah, you are absolutely right. If I do this setup, I will have to strategically place some bleed-points.
That is the main problem with this setup, a lot of connections and bends.

1303Steve wrote:I didn't realize your car was a 1303. Maybe get a space saver spare and mount it on top of your fuel tank and then use the spare wheel area for your radiator.

Than I'd have to place the radiator at an steep angle. I am worried this will affect the effectiveness of the radiator. The airflow will come in at an angle too.

1303Steve wrote:Bugs@5speed do a low front mount profile radiator for 1302/1303s.

Yeah, I know, allthough it is probably rightfully priced, I can't spend that kind of cash on my beetle. I will have to do with some junk-yard radiators.
It is a nice multi core radiator, btw.

1303Steve wrote:Also do a search on here for users called Jak Rizzo and 1303 and look how they did their front radiator set-up.

I will!

1303Steve wrote:As for running hoses front to back, this what I did on my old 1302, the 1.5 inch stainless tubes followed the chassis bolts in the heater channel.

Thanks for posting your pictures.
I am thinking of running them under the tunnel. I allready have my fuel lines following the chassis bolts under the car. I guess that mounting hot coolant pipes directy next to the fuel lines is not a good idea?

Are there any thoughts on running flat square pipes? This might help in ground-clearance.

gerrelt wrote:OK, I've come to the conclusion that the rear mounted radiator doesn't completely work in a full body beetle. It works fine while driving around town and on country roads (80 km/h) with the assistant of fans, but at the highway it just doesn't work.
At 120 km/h for a long time the temperature rises over 100 degrees celsius.

That's the problem mine had, it would get air up to about 100kph but around there and above the air wouldn't be able to turn up and pass through the radiator. The scoop on the trailing arm seems to have fixed my problem, but mine is a Baja so I get a lot of air flow under the car. I reckon some scoops through the side of the car in front of the rear fenders would help too. I just don't want to go cutting holes in my body.

Baja Wes wrote:I reckon some scoops through the side of the car in front of the rear fenders would help too. I just don't want to go cutting holes in my body.

Yeah, my thoughts exactly. Scoops in the side might work, a lot of sportcars use it also (the Ferrari Testarossa has big vents in the side to cool the radiators). But I don't like the way it looks AND I want to keep my rear seat.

I have a bit of an interesting update to my rear radiator set-up. In the last year or so I noticed the temperature gauge start behaving a little odd. Ocassionally it would go up a bit higher than normal and then come back down. So I changed the thermostat first and it didn't fix it.

Then I thought maybe it was my waterpump, as far as I knew it was the original 1992 waterpump. So that convinced me to convert to a Davies Craig EWP (which also allowed me to remove a bunch of junk and unwanted belt off my engine).

After I install the Davies Craig it still had odd behaviour. Sometimes it would seem to cool too much, and other times it would say it was overheating (the Davies Craig water pump controller has a digital temperature readout in 5 degree C increments). Something was still odd.

So on the weekend I decided to have a good dig through my wiring harness. I checked all 6 relays for the 2 cooling fans (yes, 3 per fan). I found one of the relays had died. It had a water proof cover, but was sitting upside down, so it filled with water and corroded out. But even after replacing it I noticed that second fan still didn't come on at all. All the fuses were fine. So I decided to unplug both fans and test them. Well the working fans plug didn't want to come apart, and when it finally did one pin was really corroded. So I think that had been the recent problem. The corroded pin has been intermittently connecting, so sometimes it would work, sometimes it wouldn't.

But why didn't the other fan work. Well after more testing and chasing wires (I still don't have a wiring diagram) I found something. I found the earth wire for the second cooling fan, and I had never connected it to anything. So the whole time I have only ever had 1 of my 2 thermofans working 🙂 What an idiot...

So it cools a lot better now 🙂 I am going up the beach this weekend, so it will have a good test then.

thanx for filling us in on that mate. nice when people are honest about their mistakes. 👍

be interested to hear what your feedback from the weekend is.

gerrelt wrote:Than I'd have to place the radiator at an steep angle. I am worried this will affect the effectiveness of the radiator. The airflow will come in at an angle too.

Hi

Jak Rizzo is running his radiator at pretty steep angle, the angle does aid with cooling as it forces the incoming air around a corner which wipes of more heat, you must have it all boxed in to make the air get forced through and do its work.

Steve

Jaks radiator

This is an old thread! Good to hear about your discovery Wes. Have fun at the beach!

I just realised I never updated this thread anymore.

I didn't do the dual rad setup because I couldn't find a suitable small rad for the front, and all the bends and connections would be too complex.

So, I just cut a bigger hole in the front, and placed the original radiator there:



With rad and fans installed:


With the cover on it:

As you can see, I now put my spacesaver spare wheel upright. I only loose a little luggage space this way.

Put some holes in the front:

I am quite sattisfied with the looks:


Made some coolant pipes out of exhaust pipe, used a bender, but welded the tight bends:


Painted and installed:

In engine room:


After a leak I replace a piece of it with flexible hose to make room for engine movement:

This solved a "hose walking off" problem in the right rear.

Some diagrams illustrating bleed points and reservoir position:



The hole system now takes more then 10 litres of coolant... 🤪
A long piece of small diameter coolant line is used to bleed the air out of the radiator. I hang it high, taped to the front decklid, so it will be higher than the fill reservoir. Then I start filling the system through the reservoir. When it's totally full I plug the before mentioned small diamter coolant line and hide it rolled up somewhere near the radiator. This works very good and simple.

It cools great now! The (dual) fans only came on briefly when standing still for a long time on a hot summer day. That happened two times during the summer season. They haven't been on since!
The temps stay on 90 degrees.
I've done some long trips now, on which I drive at 130 km/h for longer periods of time (1 hour or longer) and the water temp then sometimes rises over 100 degrees. But, I don't trust the sender, because the oil temp stays at 90 degrees. And (with the rear radiator setup) the fan sometimes switched off while the water temp gauge read 110 degrees. The temp switches of at 92 degrees... I think the sender is influenced by external heat sources.

It sure is fun passing all those modern cars (and some beetles) at 130 km/h in the left lane! Most people don't believe it.. 😏

All I want to do now is replace the distribution belts and tensioners and place the airfilter in a different spot or shield it from hot air.
Here in the Netherlands it is getting colder (fall) and I noticed the engine is starting to run better. I think it picks up hot air from the engine.

I surely enjoy the proper heater now. 😵‍💫

Future plans:
- rear disc brakes (no more adjusting drum brakes)
- LED daylight running lights (hidden in fog-lights)
- create some rain gutter fillers to reduce windnoise at higher speeds (see: www.vwkd.co.uk topic)

See my page for more detailed stories and pictures of the conversion.

I can't even remember why I didn't realise only 1 fan was working when I first did my conversion, but I think I thought it just wasn't coming on because I hadn't hooked up the air con yet (I figured it was the condensor fan at low speed, and then a cooling fan at high speed).

I've never known what temperature it runs at, because I just use the factor Mazda gauges with the C to H gauge. It normally ran around the middle mark, which is where the thermo turned on and off of it's low speed setting.

The Davies Craig water pump controller essential shows 95 via the LEDs.


So for the last month or so it had been going all the way up to >95oC on the controller. The Mazda temp gauge was still roughly in the middle, and the thermo was coming on and off. I think now that it was the high speed circuit of the fan turning on and off, and that the low speed circuit had the dodgy connector and wasn't working too often.

Since fixing the dodgy connection and connecting the earth to the second fan, I have found both fans turn on low speed whenever the air con compressor is engaged. So they are both condensor fans as well as cooling fans. The only problem is that I put the condensor at the front, and it has it's on fan.

So on Saturday I drove to the buggyfest. My air temperature guage said it was 31-33oC most of the drive. Naturally I had the climate control set to a lovely 22oC so the air con compressor was engaging frequently. This mean the radiator thermo's were turning on and off of low speed frequently. I found that in this condition the Davies Craig controller was reading 75oC (I had it set to aim for 85oC). So basically it was over cooling. The Davies Craig controller is supposed to slow the pump in order to reach the correct operating temperature, but with both radiator fans switching on and off of low speed it wasn't able to do so. I have the controllers temperature sensor in the cold side of the radiator.

So I figured I was going to have to turn the air con off and see if it warms up (I didn't want to, it was hot outside). Once it was off the water temp came up to the 85oC, occasionally up to 90 and back to 85. Then I switched the air con back on and it went to 75 again.

I think this is ok. It would be nice if it got a little warmer. My thermostat used to be in the cold side and it was supposed to be 82oC, so it's obviously only a little colder than what the factor wanted. The Mazda temperature guage is still reading basically in the middle, but just a little to the left (the cold end).

This weekend will be interesting. First there will be a highway drive section, this is where it used to get a little warm. Then in the soft sand it will get a good test. Full throttle in third gear through the soft back part of the beach would see the temp guage climb. I guess trying to cool 200HP (well less at those revs I guess) continuously does that.

Gerralt, I know what you mean about wind noise being the next problem. The beetle has a few issues. Yes there are the rain gutters, but the recessed windows are also quite a problem. Modern cars have the glass almost flush with the steel body. On the beetle you get little eddies in front of the rain gutters, behind them, behind the steel door frame where the glass starts, and in front of the steel door frame where the glass finishes. I used some stick on foam strips to try to make my quarter windows seal better to reduce the noise a little (foam strips made to seal house door frames).

Hi gerrelt

That is a very neat set-up, I really like the way you have been able to keep some usable boot space.

On my WBX powered 1302 I could fill the coolant from a dry fill at the header tank in the back and then overfill the overflow tank and after a few warm up and cool down cycles any air would be expelled from the header tank and be replaced by the extra coolant in the overflow tank.

Wes, I have one of those water EWP systems that I was going to fit it to my WBX, I will be interested to see how it goes long term on your car, and where you live and drive should give it a good test, I may fit it to my STI motor.

Steve

@ Wes:

Be careful fella as a lot of modern factory fit gauges are "dead" between 70-100° apparently. This is so that the driver doesn't panic about fluctuations/overheating!

Yeah, I think that's the case with mine. The EWP controller can go up and down a lot and the factory gauge doesn't move. The thermofan hi and low switching points should be pretty accurate and consistent though.

just remember the old Leyland mini in the front on the side guard.

the old speed way cars 20 odd years ago i remember them being in the back of the car where the back seat use to be.

and this one.

ElusiveStranger wrote:@ Wes:

Be careful fella as a lot of modern factory fit gauges are "dead" between 70-100° apparently. This is so that the driver doesn't panic about fluctuations/overheating!

mmm, that would explain why my parents subaru never moves from "normal" even on a hot day, while I watch my buggy's gauge go up and down according to the conditions. I guess it makes sense...also gives me a little more faith in my setup.

Gerrelt, I'm not surprised you went with that in the end (sorry if I sound like I'm gloating, I'm not). For a street car, the front makes the most sense. And congrats on your nice clean installation too. No one would be any the wiser until you carved them up. 😂

BTW, can't get over how much the alfa looks like a subaru..or the other way round maybe, but you see what I mean.

Thanks guys, for the compliments! 🙂

Yeah, it looks a like a subaru engine, especially the intake manifold. But it has quite a few differences. The oil filter is in a totally different position, the sump is a lot shorter (no shortening needed), and the thermostat is on the hot side.
The waterpump inlet is a bit in a awkard position, though.

Those standard temp gauges can't be trusted. The temp gauge that belongs to the Alfa 33 my engine came from has 70 degrees in the middle, see:

When the car is at operating temperature, the needle is in the middle, so everybody thinks, that this engine runs really cool. Wrong... the thermostat is open at 89 degrees, the fans switch on at 92 degrees... So, like all other cars, the operating temperature is around 90 degrees.
Another example of original temp gauges that are made to give the driver a good feeling instead of telling the truth 😂...

I made it back from the beach yesterday, but couldn't post on the forum as the electrons in my house were broken (due to the massive storm that hit us).

So I tried the following; up the highway with my little scoop on, up the beach with no scoop, back down the highway with no scoop. All of this was with the water pump controller set to aim for 85 degrees C.

Highway with Scoop
Temp: 30-31 deg C (87oF)
Air-con On - Cruising it sat around 80oC in either 100 or 110kph zones. Within 1km of exiting the highway it was back to reading 75oC.
Air con Off - I only did this for a short period in a 110 zone, and it went from the 80 to 90oC and stayed there. I figured that 90 deg C was when the radiator cooling fans must turn on to low speed.

Beach with NO Scoop
Temp: 30-31 deg C (87oF)
Air-con On - It normally hovered between 75 and 85oC. Depending on how fast I was going and whether I was driving on the soft or hard sand. Most of the beach is 50kph now, with only a small 80kph section.

Highway with NO Scoop
Temp: 33-34 deg C (93oF)
Air-con On - It normally ran around 90oC, but if I went over 110kph (particular overtaking on the very long hill sections) it would go above 95 deg C. Off the highway (60-70kph) it ran around 80oC, except for when I had to out accelerate a Supra from the lights before the form 1 lane section forced him to take his rightful place behind me, at which point it went to 85oC.

So the first two situations I was happy with. It was nice and stable, perhaps a little on the cold side at times, although the Mazda gauge always read a normal temperature in the center of it's travel. Even when it went over 95oC on the controller the Mazda gauge barely moved. I remove my scoop on the beach because all it does is scoop sand onto the radiator and engine, which isn't very good. I left the scoop off on the way home just to see how much of a difference it made. I was surprised how much hotter it was running, even when the air con fans were on. I think it has confirmed my thoughts that I get a dead pocket at high speeds, but also that I get a lot of recirculation within that dead pocket. Air must come out of the radiator and goes underneath, to recirculate. The scoop must probably push this recirculating air away more than anything else. It's kind of surprising because the scoop is so small and simple.





My radiator sits above the gearbox. I have it seal to the cover plate which is at the front/top of the radiator. I also have the sides sealed to the body. I just don't have anything going from the back/bottom of the radiator to the bottom of the car. Mainly because this would be difficult to do with all the other parts in the way (starter, exhaust, gearbox, fuel lines, engine cradle bracing, etc). The two thermo's are fully shrouded so there is no area of the radiator that is not under the suction of the fans.







If I get bored enough over xmas, then maybe I will try making some sort of panel that goes from the back/bottom of the radiator down to the bottom of the car, to stop recirculation.