very nice but don't forget the blow of valve or you will be picking bits of your blowers vanes all over the state
also get the dizzy right or you will be tearing your hair out wondering why it won't rev
aintgotitmusthaveit 路
That was the plan Greedy, looking for a pop off/pressure relief valve. Any recommendations?
The way I see normal blow off valves work is they are vacuum driven off the vaccum found upstrem side of the Sc inlet in a draw through application.
So when you close the throttle the blow off valve is sucked by the vacuum driving the blow off valve to open and allowing a positive pressure on the down stream side ( from over spoooling) to be vented.... I think
splitbusaustralia 路
Nice looking install!
However, roots style blowers don't require, or normally use a blow-off valve.
Ideally you work out the boost you want to generate (above atmospheric pressure) for your engine capacity and rpms. You look at what your blower
produces and calculate the pulley sizes you need to generate the required amount of boost....
You don't get overspooling with a SC because the drive
is directly related to engine rpm (unlike a turbo). You are better off doing the calcs rather than trying to control 'unknown' boost levels with a BOV on an SC....
regards
RobK
Joel 路
Rob BOVs in this situation are installed as blow back protection - not to vent boost
even the original Judsons and shorrocks have the same thing
if the engine spits back thro the carb its gonna try and spin the blower backwards and as its belt driven that aint gonna happen so as Steve said there will bits of blower lobes everywhere
Nick, i just run a garden variety Greddy style with no vac hooked up bolted to the blower manifold and as i pointed out in my thread its saved the blower a couple of times
just set the spring tension right so it wont leak boost but will open on a spit back
ive had mine upto 10psi with no dramas
splitbusaustralia 路
Ah .... sorry I saw the comment relating to vacuum and overspooling and thought it was going to be used to try and control boost level.
Obviously good insurance and well worth doing although some would argue the serpentine style ribbed belt will slip and it's the Gilmer (tooth) style drive setup that causes a SC to pop....but why test that?
regards
RobK
Dilbert 路
should just put a 911 rear end with a stock motor in it and be done with it.
Joel 路
why? did ur mates, uncles, freind do that back in the day? 馃槀
you can buy em on US ebay from dale wilch and land
em for about US$65 (not that hard to make one in this
style either.....)
regards
RobK
greedy53 路
i foiund a wrx on ebay cost $45 works well as my little unit was playing rough for a while, and back fireing like mad with no damage
and as for putting in a porsche rear end in $$$$$$ my blown motor cost all up $500.00 and $350 was for the blower to get a 80-83 bhp my first job that i built with no money i made a blow of out of a 1 inch pipe with a screw on top a valve spring and some drilled holes at and a tap washer now thats doing it the hard way but it worked. and as for roots type blowers they had a blow back plate that blew when it back fired if you watch the drag cars you may see the plate blow and sometimes it just blows the entire blower
good luck
Joel 路
yes this is the great fatso BOV for the budget conscious 馃榾
that one would be fine nick
i just went the plumb back style cos one of these days i was gonna plumb it outta the engine bay just for safteys sake
aintgotitmusthaveit 路
HI guys throwing around ideas on the belt drive
Up for comment, thinking of doing something like this:
Why? To be different to the great work that others Like Joel on this forum have done, and secondly have a set up that can be introduced without engine removal.
In short its a set up like a serpentine belt, the difference being the tensioner is a double pulley with the second pulley driving the supercharger itself.
This allows the engine to be removed from the car without the additional obstruction that results from having an additional pulley sticking out 2" past the crank. (my speedsetr replica has even less space than a stock beetle!)
This also allows the changing of boost by changing the tensioner pulley without removal of the engine to gain access to the main crankbolt.
You can use the standard generator washers to establish tension on the generator side allowing the "tensioner" to have a single plane of adjustment for the superchager side (may not need that additional tensioner on the SC belt).
Hope I described it ok.. Joel & Greedy any comments?
PS Greedy I see your set up is great and works but I do not want to cut the shroud in 1/2 yet...
Comments will be appreciated.
Joel 路
Hi Nick
thats actually very well thought out
theres a bit of extra engineering involved in setting it up i cant see why there would be a problem if you could get good tension on both belts without to much strain on the idler pulley it should work well
i toyed with the idea of running a scat serpentine belt kit running the blower as well but couldnt get it to all line up right
im still thinking of going the rib belt for the alternator on my car after witnessing first hand the difference it made on kims bug
aintgotitmusthaveit 路
Joel, do you think I will have the generator side contating the belt enought to actuately drive the SC without slipping?
I was planning on keeping the std V belt on the Gennie side of things
greedy53 路
well for my 2 bob worth. i think that running both on the middel pulley will give you a headache when doing the tighten up as you will need to adjust the genny pully from the genny's aju8stable system because if its loose the engine will over heat with a slow fan and because these blowers will generate head by just being a blower and heating up the air
so try an keep things as simple and if you do a blower belt it will still run well with a standard system without the blower it's all a juggeling act but when you get it right it feels really gooood
Joel 路
Nick are you keeping the 5pk belt on the blower?
cos your gonna have to create a hybrid Vbelt/rib belt mule pulley if your staying Vbelt on the genny
vw54 路
No you have it all wrong
the SC stands for Sexy Car
Joel 路
so where did it all go wrong with 911sc then?? 馃槀
vw54 路
well its litterly 9 11s which is double sexy LOL
greedy53 路
sc isn't that single cab
aintgotitmusthaveit 路
ok an update is due
Thanks to a buddy at work I have had parts machined up.
First off a press fit, dowelled and pinned bit of Aluminium onto the original SC drive allowed the offsetting ofthe belt closer to the crank
While a removable lower pulley hanging off the main wheel (Held in with Aerospace Fasteners Hiloks) which allows boost to be modified by changing the pulley without remoival of the main crank bolt!! http://www.postimage.org/image.php?v=gx1NR7Wr http://www.postimage.org/image.php?v=gx1NR2X9
Next BOV and then ignition... Stay tuned
Golde60 路
looking good guys
Gracey 路
Looking good, I like the inlet manifold design.
Be interesting to see how it performs.
Turbo54 路
Looks good, I personally after having experience with blowers and pulleys would of run a toothed belt rather than a serpentine style. I found my old blown engine to slip at big revs and ended up snapping the bolt off in the snout of the blower.. These were brand new pulleys and belts so I changed it over to a gilmer style and could run a slack belt and never slip. It is worrying how much tension and load must be on the crank and bearings with the belt pulled so tight to one side. If you could, this is what I would do. Good luck T54
aintgotitmusthaveit 路
HI guys just an update, Tensioner sorted and belt is on:
Here are the picts, still waiting on over pressure valve to arrive from US.
Still have not figured ou here to route accellerator cable,
After that is sorting out the remaping of the dizzy.
Here tis:
Joel 路
Nick i just ran a longer one with its own spring type conduit from a bike shop
fits inside the standard vw tube
let me know if u need details
cb john 路
This is very similar to what I did some time ago...
Joel 路
john have you got any pics of that one finished?
pretty much identical layout to mine
cb john 路
I'll dig some out...if you have an engineering common sense, you come to the solution which is right on the money...there isn't much to improve on the basic layout...just a minor variations...the pulleys are the biggest open field....I've started to modify original pulleys, for carby model skipping el.magnetic clutch and reversing the pulley, which gives me about 22.0 mm closer to the blower.I'm using heavy harmonic ballancer, where is easy to attach additional pulley...no welding and no need for balancing...
Joel 路
yep the pulleys/belt drive has definately been the most frustrating part of the whole exercise
ive redone mine several times and stilll not 100% happy
altho i pulled the power steering pump off my subi engine on the weekend and the pulley from it looks perfect for the stock SC12 clutch setup
aintgotitmusthaveit 路
guys i used the original pulley and press fit and doweled on a bit of aluminium from which I then machined in a v belt groove pattern.
That way youy can have the original clutch and bring the belt closer to the SC: [img]https://www.postimage.org/Pq1iGWBA.jpg[/img]
PS Joel any picks on teh accelerator cable? Did you just splice it to the existing cable?
cb john 路
Original clutch is quite useless unless you have fully programmable injection...that is why I just turn it around...
kroozzn63 路
cb john love to see the pics . And a big question out to all ! Will anybody here "when things are all sorted out, reliability wise" be willing to share a plan to build this kit so all us aircooled lovers can do this ?
P.S another idea reading about the stress on the crank with "two pulleys" could u make a bracket on the lower part of the motor with a tentioned wheel that counter stresses the crank from inside of nicks alluminium fabd pulley? or is that getting out of control and too much?
cb john 路
This is the kit less Dell...
Joel 路
wow, that is an exact carbon copy of mine 馃槀
Brendon, unless you got a blower real cheap i'd go turbo as they're everywhere, cheap and give the same results
SC12s are getting harder to find cos the toyota boys are running massive 175mm nevo pulleys and overboosting them
only difference between the setups is u have to make a header instead of belt drive
altho mine is off and retired now to make way for the new project it ran fine, it wasnt reliability issues as such more me being fussy and changing things all the time
apologies nick for going OT with your thread
cb john 路
With given hardware there is only one way of doing it...every solution would look alike...
Joel 路
yea i know what u mean i tried to find other ways to mount itthat looked neater but theres just no way to get it fit around everything else especially in a bug
i wanted to try one on the subi but its even more cramped for space
cb john 路
I did much neater job using Aisin blower, but that one is small enough to line up the drive belts... not much power but...good for about 60 kW..
Sorry for messing up the topic...
aintgotitmusthaveit 路
Ok guys an update is long over due.
I had the engine tuned and dynoed naturally aspirated. It was producing 70hp atw. Quite surprising I expected a bit more!
Pulled the engine out and decompressed it using copper shims between barrel and head. Got it down from 8.5:1 to 7.9:1.
Re assembled it and on Saturday took it down to the Vw performance centre for tuning. Hope to get it back before dotv ...
greedy53 路
a little gem fo those blowing the t3 front pulley has 3v belt sections wish i HAD OF KNOWN THAT WHEN DOING MINE should just replace the pulley on the type 1
aintgotitmusthaveit 路
What went wrong??????
The engine produced 70h/p naturally aspirated at 8.6:1 compression and with twin webers.
I dropped the compression to 7.9:1 and installed the sc.
The boys at vw performance told me that the set up only produced 3psi of boost resulting in wait for it...90hp馃檨
I was hoping for at least 6psi....have I made the crank pulley too small which means the sc is not turning quick enough?
To double the boost does that mean i have to spin it twice as fast? Are these things linear? If that's the case I have to nearly double the pulley size on the crank?? That doesn't make seem right....
Would reducing my combustion chamber size (upping my compression ratio) increase my boost?
The original 4agze motor which is a 1600cc (mine donks av1916cc) produces nearly 8psi driving a 145mm sized crank pulle ( mines 130mm same size as joels), so what has gone wrong?
Am I getting too much blow past having a mild cam? I was told it's a engle 120 but with only 70hp NA I'm thinking it was more likely a 110.
Else perhaps the clutch on the supercharger is slipping.... Any guys who have tried this set up if you could give me your boost numbers pulley sizes an engine size that would help....
matberry 路
What heads have you got?
Joel 路
That cam is a worry, I found the stock one in my 1600 performed perfectly with the blower but the Tighe 416C which is equivelent to a W110 in my 1776 really didnt play nice.
ian.mezz 路
dont you just pull the vacuum hose off the valve to get more boost????馃槉
Joel wrote:That cam is a worry, I found the stock one in my 1600 performed perfectly with the blower but the Tighe 416C which is equivelent to a W110 in my 1776 really didnt play nice.
aintgotitmusthaveit 路
Mat I have 044 heads.
I am guessingthey are the stocl cast type
mymedusa 路
aintgotitmusthaveit wrote:( mines 130mm same size as joels), so what has gone wrong?....
if you drive the same supercharger like joel at the same ratio like joel...馃槈
you will get nearly the same hp like joel at the same rpm..thats it.
stock cams are good supercharger camshafts because of small overlap.
you have better heads and more displacement than joel so you will have less boost. boost is a messurement of restriction..you don't want boost, you want hp and torque.
all you need is more blower speed. if you have dynoed it with the 3psi...than you could nearly exactly give the blower the speed you want for the hp you want. in a very close range...lets say 1-3hp. thats because it is "just" a pump.
you could also limiting your engine to 50hp if you want just via slowing down the supercharger...
an easy first way to calc is. over the thumb for "dummies" but works in an easy way.
displacement of the supercharger in cubic feet x 0,85(ca. pump efficency inclued hp lost via pulley) x blowerspeed ratio x peak hp rpm (you have to feel where it is) / 1.5 = peak HP
wishes from germany
chris
matberry 路
Which 044's mate, cnc'd or un ported and valve sizes etc.
As said above, your engine is larger capacity than the blower was designed for so you will need to overdrive it more, maybe another 10% or so???
70 rwhp from a 1915 with 'basic' heads is about right.......main thing is the cam choice to get the blower working....there's a big difference from 110 to a 120.
aintgotitmusthaveit 路
After a night up reading everything i could find looks like if it's not a boost leak, that I simply aren't pumping hard enough; I'm not spinning the thing fast enough!
The sc is made by ogura. http://www.oguraclutch.co.jp/english/e_products/sc/sc_siyou.htm
They recommend a 11000rpm continuous for the sc12. I'm turning it at just over 1/2 that.
So yep I simply need to pump harder... So a new pulley(s) larger on the crank and or smaller on the sc.
I'm also upping my compression ratio back to 8.9:1 since I now dont expect more than 6psi boost. That will increase the effective compressionand hp. My buddies with sc12s on their mini is running they fine with 10psi boost and no intercooling.
Thanks guys-let you know how it works out!
dangerous 路
I would avoid bumping up the comp if you can help it.
And leave the cam as it is.
My maths says you will need about a 1.5 drive ratio to acheive about 14psi.
This is very dependant on the temp rise through the blower and things like cam and head ports.
Without factoring in temp rise and the associated pressure increase,
a simple maths sum will tell you that your 1915 will consume 957.7cc per revolution at 100%,
so you can assume that 14.7 psi boost will want the blower to pump about 1.915 lt per rev.
With a 1.2 blower this will mean about 1.596 drive ratio.
I always use this basic maths as a start point, and usually the boost guage will show higher than this,
due to temp rise and restrictions that occur as the blower outsrips the engine's ability to consume air.
Remember thst "boost" is just the air that has not gone into the engine.
The power gain you have acheived is a pretty good gain.
1.2 drive ratio shoul have at least 8psi.
Do some porting if you are removing the heads again.
aintgotitmusthaveit 路
Thanks dave.
I have decided to leave the compression as you have suggested, and I'm upping the sc's rpm.
As for porting can you recommend some literature for me to read?
mymedusa 路
dangerous wrote:I would avoid bumping up the comp if you can help it.
And leave the cam as it is.
My maths says you will need about a 1.5 drive ratio to acheive about 14psi.
This is very dependant on the temp rise through the blower and things like cam and head ports.
Without factoring in temp rise and the associated pressure increase,
a simple maths sum will tell you that your 1915 will consume 957.7cc per revolution at 100%,
so you can assume that 14.7 psi boost will want the blower to pump about 1.915 lt per rev.
With a 1.2 blower this will mean about 1.596 drive ratio.
I always use this basic maths as a start point, and usually the boost guage will show higher than this,
due to temp rise and restrictions that occur as the blower outsrips the engine's ability to consume air....
half right, it also shows more on the gauge because you calc with 100%
1915/2 x 0,85 will be the start of boost at such an engine with good heads. now with his dynoed engine he can calculate everything he want in an exactly way. but over the thumb will also be close to that what he want.
as i startet calc my engines at the end i allways has the pressure i calculated. supercharging is really easy to calc in compare to turbo.
go for it. 1915cc with supercharger will be a supertorquer.
my 1192cc 30ps engine has close to 150nm from 1700-3000rpm.
aintgotitmusthaveit 路
Picked up the engine and decided to pull apart the manifolds and inspect for boost leaks... Guess what... A massive crack along one of my manifolds.... Looks like I sanded thru the weld.... Nob! So potentially more boost on the agenda馃榿
Welding up tomorrow. Engine is otherwise in as tuned.
Fitted a cheap Chinese alt, so have to ditch the regulator plus wire up the guel pumpr.
Fingers crossed ready for the dotv!
aintgotitmusthaveit 路
So after welding up the inlet manifold leaks, I decided we needed a but more boost too!
I checked with the OEM of the sc12 and it's rated to 11000rpm continuous, so I decided I could easily get away with a 7" crank pulley (with a 5" @ the sc) and a redline of 6000rpm.
The pulley looked wrong! It was huge! It's so big that it hit the new side winder exhaust so out with the torch and peening hammer. Lost interest and decided it was time for a drive, so fitted the old exhaust and started her up.
After a few hicups I took her for a drive yesterday for the first time.
Drove the car, Change into 2nd at 2500rpm, bury the foot and the rear lights up!! Awesome power but pinging under load so need to retard the timing or recurve. Makes the n/a 1916 feel like a slug!
Gracey 路
Woohoo!! That must feel good.馃憤
fish26 路
well done Nick, I bet its a blast to drive. You running locked out dizzy?
Joel 路
aintgotitmusthaveit wrote:Drove the car, Change into 2nd at 2500rpm, bury the foot and the rear lights up!! Awesome power but pinging under load so need to retard the timing or recurve. Makes the n/a 1916 feel like a slug!
Ah that takes me back
I remember when I first put the blower on my 1776 doing the same thing.
Poor thing pinged it's tits off too at 8.8cr had to drop it back to 7.6
How much advance did you end up running?
I found 22* was a good happy medium
aintgotitmusthaveit 路
Thanks Joel.
It's been a bit messy. I had locked out a dizzy to 16 degrees for the old pulley
- something went wrong on that dizzy-don't know if the compufire gave up the ghost but tried an old dizzy and I found I could run it at 32 fine under the pissy boost it was producing
Obviously now with more boost that's not the case
I'm now going to lock this one out.
I gave dropped the compression to about 7.9:1.
Craig Torrens 路
why go lower comp and higher boost?
why not just run the higher comp with slightly less boost ??
aintgotitmusthaveit 路
Hi Craig I agree, was just trying to be conservative.
I haven't driven this thing in earnest yet to see if I have cooling issues. If the temps prove ok I'll pull out the copper gaskets and bump it back to 8.6:1
aintgotitmusthaveit 路
Ok so I broke the clutch cable and lost interest for a couple of months
Eventually got round to fixing it and drove it on the weekend.
The oil temps getting to around 94c after 30 mins of driving.
The tinware on this thing was even hot!
So don't think I'm cooling adequately. The install has blocked the flow getting in thru the deck lid.
It's at least 15/20c more than when it was n/a!
So need to mount a bigger remote oil cooler.
aintgotitmusthaveit 路
Ok an update
Since fitting the 96 plate oil cooler with fan the car has been awesome
I've been collecting some bits for the next evolution:
Waiting on the bench to be fitted:
Smaller pulley for the supercharger
Msd ignition
Water methonol injection
And... 55mm X2 throttle body and mt4 ecu for fuel injection
fast68 路
Any idea what cyl head temps your running? What did you PSI work out to after you fixed your manifold?
aintgotitmusthaveit 路
My first pressure reading was at the tuners, I haven't fitted a boost gauge yet.
So I can't tell you... Similarly not monitoring head temps- all that's getting fitted this time round!
fast68 路
Can you give us a run down on the specs of your 1914, im also currently looking at putting together one with an sc12 and picked one up the other week, just trying to decide weather to use a stock case or a wasser boxer and convert it over to air cooled.
aintgotitmusthaveit 路
I've done both Craig.
Because now I can retard the timing with the msd distributor
