| [ Total Views: 9528 | Total Replies: 39 | Thread Id: 96542 ] |
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 Timbo KG
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| posted on April 23rd, 2012 at 11:56 AM |
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Subaru Conversion - Handling question
Hi All,
I have been seriously considering a Subaru EE20 (Turbo diesel) conversion for my Karmann Ghia, but am concerned about the extra weight, hanging off
the rear. From what I can gather the EE20 is about 20kg heavier in total than an EJ22.
I like the idea of a powerful and torquey engine, but not if it results in "1950's American style" handling (ie good in a straight line, but tip
toe around corners).
What are people's experiences with the heavier engine? Are there any handling "eccentricities" and if so, how did you combat them. By the way, I'd
prefer real world experiences rather than theoretical views.
(or if there is already a thread about this, smack me about the head and point me in the right direction)
Thanks in advance.
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pete wood
A.k.a.: figure itout
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| posted on April 23rd, 2012 at 12:24 PM |
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Timbo, great question mate. It's a question more people should ask.
In terms of an answer, let's start with reality.
REALITY; aircooled VWs are chronic understeerers in stock form.
This is the mark of rear-engined cars. ACVWs mask these tendencies by being chronically underpowered and having chronically soft suspension. Linkpins
and swingaxle are even worse in this regard giving neutral camber up front and negative camber out back. However, most of this can be easily improved
via some simple mods that have kept FVees fast for many years.
What happens when you add a heavier motor to the back? Well 2 things. Like you imagine, the understeer gets worse. However, beyond the understeer with
all that extra power, you then get snap-oversteer. In other words you go; plough, plough, plough, SNAP, totally sideways and fighting to stop it
pointing the opposite direction. So to go fast it means driving the car with the handbrake and the throttle for the most part.
How to fix that?
1. move everything you can to the very front of the car; battery, fuel tank, radiator, spare tyre, tools, etc.
2. cut off every thing you don't need in the engine bay, lighten the back of the car via speed holes, use lightweight fibreglass panels on the back
of the car, get rid of the back bumper, use ali/composites/plastic instead of steel for everything in the back of the car, etc.
3. move the engine and trans as far forward as humanly possible.
This last step is the hardest and means you need IRS. It's major surgery and not for the faint hearted, but lots of people have done it.
If you do all this and get it all right, you can end up with a car that has a 50:50 front rear weight setup. I spoke to a porsche rally car owner
years ago and he said they managed the 50:50 weight split without too many dramas. It just means thinking hard about everything you put on the back of
the car. Of course if you manage 50:50, the car will handle amazingly.
Your trying this with a ghia will be much easier than my struggles with a buggy. Even still, the buggy showed a marked improvement as I removed weight
from the rear, stiffen the rear chassis and moved heavy things forward.
Hope that answers your question.
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HappyDaze
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| posted on April 23rd, 2012 at 12:44 PM |
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^^^^^EVERYONE with a rear-engined car should read this.^^^^^
I'd rather wear a Beetle out by racing it than by polishing it!
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ian.mezz
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| posted on April 23rd, 2012 at 12:49 PM |
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mate dont waste your money on a Turbo diesel.
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HappyDaze
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| posted on April 23rd, 2012 at 12:55 PM |
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| Quote: | Originally
posted by ian.mezz
mate dont waste your money on a Turbo diesel.
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Unless, of course, you want to win Le Mans 24 hrs.
I'd rather wear a Beetle out by racing it than by polishing it!
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1303Steve
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| posted on April 23rd, 2012 at 01:44 PM |
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Hi
I'm pretty sure that the Subaru engine uses a CAN BUS system to run the motor.
I think http://www.alldrivesubaroo.com.au/ are working on a system for late
motors like that to work in earlier cars.
Good explanation Peter, you cant drive all differently configured cars the same way. No matter what sort of rear engine you have you will have
understeer on tight low speed corners, it all comes down to the nut behind the wheel.
Steve
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Subarugears
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| posted on April 23rd, 2012 at 03:30 PM |
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All drive Subaroo have finished defeating the CAN bus on late model ECU's - petrol or diesel. It's just a matter of getting the ECU flashed. You can
also get a stand-alone ECU for the EE20 diesel - made by Hurricane. I hear that Bosch ECU's work on the diesel's as well. Lots of options really.
For handling - battery, radiator in the front for a start.
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ian.mezz
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| posted on April 23rd, 2012 at 03:58 PM |
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 in the current economic climate its not
economical to put a diesel motor in a petrol car the cost far out way the returns.
.
.
sand bags 
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 helbus
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| posted on April 23rd, 2012 at 07:16 PM |
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I have always found our Beetle to handle heaps better when there are three slabs of beer in the front
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vlad01
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| posted on April 23rd, 2012 at 10:01 PM |
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| Quote: | Originally
posted by pete wood
Timbo, great question mate. It's a question more people should ask.
In terms of an answer, let's start with reality.
REALITY; aircooled VWs are chronic understeerers in stock form.
This is the mark of rear-engined cars. ACVWs mask these tendencies by being chronically underpowered and having chronically soft suspension. Linkpins
and swingaxle are even worse in this regard giving neutral camber up front and negative camber out back. However, most of this can be easily improved
via some simple mods that have kept FVees fast for many years.
What happens when you add a heavier motor to the back? Well 2 things. Like you imagine, the understeer gets worse. However, beyond the understeer with
all that extra power, you then get snap-oversteer. In other words you go; plough, plough, plough, SNAP, totally sideways and fighting to stop it
pointing the opposite direction. So to go fast it means driving the car with the handbrake and the throttle for the most part.
How to fix that?
1. move everything you can to the very front of the car; battery, fuel tank, radiator, spare tyre, tools, etc.
2. cut off every thing you don't need in the engine bay, lighten the back of the car via speed holes, use lightweight fibreglass panels on the back
of the car, get rid of the back bumper, use ali/composites/plastic instead of steel for everything in the back of the car, etc.
3. move the engine and trans as far forward as humanly possible.
This last step is the hardest and means you need IRS. It's major surgery and not for the faint hearted, but lots of people have done it.
If you do all this and get it all right, you can end up with a car that has a 50:50 front rear weight setup. I spoke to a porsche rally car owner
years ago and he said they managed the 50:50 weight split without too many dramas. It just means thinking hard about everything you put on the back of
the car. Of course if you manage 50:50, the car will handle amazingly.
Your trying this with a ghia will be much easier than my struggles with a buggy. Even still, the buggy showed a marked improvement as I removed weight
from the rear, stiffen the rear chassis and moved heavy things forward.
Hope that answers your question.
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whats the weight distribution of a bug?
^ All this sounds scary if its true
It actually sounds like what my buggy I used to have was like. Thankfully the late type 3's are nothing like this, well maybe a little pendulum
effect on loose gravel but my daily front engine car is 10 fold worse on anything but bitumen so I guess that doesn't count?
I bet a 1303 would be sweet as.
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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SebastienPeek
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| posted on April 23rd, 2012 at 10:11 PM |
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Vlad,
Got Zelda completely 180 degrees in the wet the other day.
Definitely a lot difficult to handle than a FR car.
As soon as an RR car builds up momentum in the rear, all hell breaks loose.
Especially in the freaking wet and no tread on the rear tires!
Will definitely be looking into getting the weight distribution better and what not.
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bajachris88
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| posted on April 24th, 2012 at 08:42 AM |
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Dubster's 1303 has a consistant desire for oversteer in the wet and hasn't nabbed either of us in loosing it.
Even without trying, the rear end loves to go out before any sign of understeer is present. I guess the strut front and IRS helps massively, but the
front is also lowered with some pretty beastly sway bars at the front too. It has stock tyres/wheels. Different kettle of fish compared to old
swingaxle/beam front. 
(ô_!_/ô) (ô_!_/ô)
69' baja: kombi box, thing spindles, irs, disc front, type 3 rear drums, 2 inch lift kit, 31x10 rears.
New engine in process: 94mm p&bs, 74mm C/w chomol Crank, 35.5x39 SP heads, turbo. Wierd combo, hopeful torque monsta! |
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HappyDaze
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| posted on April 24th, 2012 at 08:45 AM |
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| Quote: | Originally
posted by vlad01[/i
whats the weight distribution of a bug?
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Take a look at the position of the jack point, in relation to the front & rear wheels, and that will give you some idea.
I'd rather wear a Beetle out by racing it than by polishing it!
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modulus
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| posted on April 24th, 2012 at 10:33 AM |
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| Quote: | Originally
posted by pete wood
... aircooled VWs are chronic understeerers...
This is the mark of rear-engined cars.
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I agree with all of the practical advice that Pete has given.
However, the explanation is a bit ropey. Additional weight at the rear of a car will tend to cause oversteer rather than understeer. As can be seen by
that later comments on 1303's etc., this is the case with IRS/ball-joint pans. The tendency of early pans to understeer at moderate speeds is owed to
the overall suspension design in conjunction with the weight distribution, probably by 'intelligent design'.
Whilst 50/50 is an admirable goal, it is worth noting that the latest Porsche 991 C2 is 42% front / 58% rear, exactly the same as the Ferrari 458
Italia. Both are able to go around corners.
hth
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pete wood
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| posted on April 26th, 2012 at 01:31 AM |
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Good point modulus.
However, the oversteer is SNAP oversteer and preceeded often by some understeer too.
Something else to remember, MR (mid engined, rear drive) cars are also natural understeerers. That's why they are "slow in, fast out" cars. You
brake hard, turn in and then accelerate out. Watch some of the mid engined cars on Topgear and you'll see what I mean. If an MR car gets out of
shape, it happens fast is usually very hard to catch. Again some of this comes down to setup, but wherever you put the weight, that's what controls
the physics. If you want a well balanced car (rather than a "drivers" car), like an RX8 or MX5 for instance, you go as close to 50:50 balance as
possible.
Course there is a way to "drive around" the understeer. It involves lots of chucking the car round and lots of power. It's called "drifting".
It's not usually all that fast. 
Vlad: "Thankfully the late type 3's are nothing like this"
Sorry to rain on your parade, but they are much the same as every other ACVW. Look where the car suspension sags over the years... that's where the
weight is. Lbugs too. The difference being, you can change your front camber easily.
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bajachris88
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| posted on April 26th, 2012 at 08:05 AM |
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In other areas, what was interesting is that on road or even in mud (low traction conditions) the baja is 95% time was riddled with mass under steer.
My thoughts was the light weight of the front (which causes the front brakes to lock very easily too i noticed) would loose traction and just
'plough' in the direction of motion. I guess the 10.5inch wide tyres on the rear is what keeps the oversteer from peeping up.
Mind you with alot of effort, once you do get the rear spinning (in the mud), only then i can get oversteer to come about.
(ô_!_/ô) (ô_!_/ô)
69' baja: kombi box, thing spindles, irs, disc front, type 3 rear drums, 2 inch lift kit, 31x10 rears.
New engine in process: 94mm p&bs, 74mm C/w chomol Crank, 35.5x39 SP heads, turbo. Wierd combo, hopeful torque monsta! |
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ElusiveStranger
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| posted on April 28th, 2012 at 12:26 PM |
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| Quote: | Originally
posted by helbus
I have always found our Beetle to handle heaps better when there are three slabs of beer in the front
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But what do you do at the next junction?
Gotta say that Pete W and Modulus have some very valid posts that really should have a "+ 1" from me
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Timbo KG
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| posted on July 27th, 2012 at 09:21 AM |
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Hi Everyone,
Thanks for your comments. I have read and re-read your comments many times. Pete and Jak, your comments were particularly informative and have
influenced my decision to give the turbo diesel conversion a try. I know I have to rethink a couple of things, but I think it should be do-able.
I know that economically it makes limited sense (and the further I get into it, the more extra costs seem to emerge), but if anyone has driven a
modern turbo diesel recently, you'll understand that they have great characteristics for the street. Lots of torque down low and deceptively quick.
Now, take a couple of hundred kilos from the original vehicle and it should be a lot of fun.
I'll start a build thread soon, once some building actually starts. I'm sure no-one wants to read pages and pages of degreasing and chassis
painting, etc. I intend on outsourcing key parts of the project, but want to wait for the right people to be available, rather than paying for work
I'm unhappy with. Unfortunately, this means there are already lengthy delays (including this reply, sorry).
Thanks again, Tim
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pete wood
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| posted on July 27th, 2012 at 07:48 PM |
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A TDi motor will probably heavier than a subaru NA for a few reasons.
1. the blocks are usually iron to account for much higher compression
2. inline 4s (unless you are going subaru TDi) are longer and hence have the weight further back.
I'd actually advise against going with a TDi motor in KG for your average conversion. Coz unless you plan on building a specially designed tall ratio
trans, you're not gonna get the value out of the TDi you would in factory car. To give an idea of the sort of revs, my Pug 307 diesel does only just
2000rpm at 110km/h (70mph) in 6th gear. You'd need a very tall gearset in a beetle box to get close to that. Now if you do LOTS of freeway miles, it
might be worth it, but otherwise not. Modern efi EJs are pretty good and if you want better fuel economy you could put an aftermarket ECU on and tune
it really carefully.
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ian.mezz
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| posted on July 27th, 2012 at 08:40 PM |
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my EJ 20 bug uses 7.5lt per 100Ks
good luck .
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Subarugears
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| posted on July 28th, 2012 at 10:01 AM |
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This project is getting a Subie EE20 turbo diesel and a Subarugears 5 speed to suit. Going to be a helluva combo.
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ian.mezz
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| posted on July 28th, 2012 at 11:24 AM |
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don't you think to be moving forward and you want to do something better , you be going electric. Rather then a rattly diesel.
Diesel cars ain't big sellers in Australia.
I guess we have to wait and see if or when you finish it.
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waltermitty
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| posted on July 28th, 2012 at 12:07 PM |
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| Quote: | Originally
posted by Jak Rizzo
I tracked my car for 10 years before going WRX power & I couldn't tell the difference from before & after,
Jak
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So the WRX conversion made NO difference!
Mitchell
23 windows ...8 too many!
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waltermitty
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| posted on July 28th, 2012 at 12:35 PM |
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| Quote: | Originally
posted by Jak Rizzo
| Quote: | Originally
posted by waltermitty
| Quote: | Originally
posted by Jak Rizzo
I tracked my car for 10 years before going WRX power & I couldn't tell the difference from before & after,
Jak
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So the WRX conversion made NO difference!
Mitchell
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To the handling no, which was my reply the to the original question re: the additional weight hanging out the rear of the car
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I know what you meant Jak just taking the piss , as you know, it didn't take you long to bite though ! *) Mitchell
23 windows ...8 too many!
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Subarugears
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| posted on July 28th, 2012 at 06:14 PM |
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| Quote: | Originally
posted by ian.mezz
don't you think to be moving forward and you want to do something better , you be going electric. Rather then a rattly diesel.
Diesel cars ain't big sellers in Australia.
I guess we have to wait and see if or when you finish it.
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Customers car - they can do whatever they want, I just supply the gearboxes.
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vlad01
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| posted on August 2nd, 2012 at 02:47 PM |
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| Quote: | Originally
posted by HappyDaze
^^^^^EVERYONE with a rear-engined car should read this.^^^^^
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+1 i always do this
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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vlad01
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| posted on August 2nd, 2012 at 02:50 PM |
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| Quote: | Originally
posted by Subarugears
This project is getting a Subie EE20 turbo diesel and a Subarugears 5 speed to suit. Going to be a helluva combo.
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with all that torque its gona haul ass!
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE |
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pete wood
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| posted on August 3rd, 2012 at 12:54 PM |
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| Quote: | Originally
posted by ian.mezz
don't you think to be moving forward and you want to do something better , you be going electric.
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You're kidding, right Mezz? Electric seems cools until you have to replace the batteries, which a. weigh a tonne, b. cost a bomb, and c. are awful to
the environment. All that plastic and acid comes from fossil fuels and mining just like everything else. However, a diesel will in most cases outlast
the bodyshell it's put in and when the motor wears out, you just melt it down and recycle it all. What do you think happens to old battery acid?
This is the problem with electric cars. They're a massive marketing lie. Only honda have got close to solving this but it's still not cost
effective. Everyone else's prius is killing baby furseals and melting icecaps just the same way commodores do...
Don't get me wrong, I'd happily drive an electric car, but only if it's actually as friendly as they say.
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Subarugears
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| posted on August 3rd, 2012 at 08:02 PM |
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Ironic, there's talk about moving forward, but in a 60 year old car that has none of the hundreds/thousands of improvements that have been
incorporated into cars over that time.
Who's trying to kid who?
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pete wood
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| posted on August 3rd, 2012 at 10:01 PM |
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Nah, I'm committed. I bought a diesel family car for all these reasons... and besides, they sound cool.
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