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Supercharging a 944 - Why so hard?

Old 11-18-2017, 11:05 AM
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jderimig
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Default Supercharging a 944 - Why so hard?

So first. I will admit that SC on a 944 doesn't make a lot of sense $$$ wise, buying a turbo or an s2 is the best solution. So that should get "that" discussion out of the way. I have search this forum any many others on 944 SC threads. There are not many that end is great success or documented numbers. Many peter out before completion or do not end well. Why?

Also the target would be modest increase in HP and torque, not to create a fire-breathing 350rwhp monster. Maybe something in the 200-250 engine bhp range.

My understanding is to do this successfully you must:
1. Select the SC, match it to the flow and power you are targeting for the engine.
2. Design how to mount and drive it.
3. Size the pulley. Determine the rpm ratio (from 1) and necessary wrap needed to supply the SC required power (also available from 1 if you have the SC performance map).
4. Decide whether you are going to IC. Should be decided in step 1.
5. Design your plumping path. Get a local tube bender to fab a nice set of pipes
6. Plumb an oil supply and return line.
7. Provide a bypass.
8, Lower CR depending on 1.
9. Upgrade injectors and fuel supply depending on #1.
10. Install new engine management and tune. Don't fight with Motronic.

Have I left any "BIG" items out? Is so please add them. Of the list which are the most difficult/problematic?

-john
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Old 11-18-2017, 12:05 PM
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V2Rocket
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those are the basic steps but actually fitting them in the 944 bay is the hard part.
also, there are lots of little costs and details that pop up along the way and some people lose patience or $$ interest.

ive been chasing mine for 10 years but for most of the first 9 of those never had either money or time to dedicate more than a few hours per year working on it.
however...this past year has been different...big progress made for my SC setup so far, more to be made this weekend...

i will admit there have been a number of times i've thought just to quit while ahead and build a nice NA engine or stick turbo parts on it.
at this point i'm still doing it, just to say i finished it.

Last edited by V2Rocket; 11-18-2017 at 01:32 PM.
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Old 11-18-2017, 01:21 PM
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jderimig
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For some reason, which I do not understand, I am very tempted to try this, against my better judgement and the judgement of many others on this forum. Perhaps its insanity, but the engineer in me finds this appealing. I have wasted money is previous pursuits of less gratifying projects so that is nothing new for me.

If I do it, I would do most of the work on an engine out of the car, make the best CAD model I can of the engine bay and do the fitting on paper. Now I need to ask Santa for a spare 2.5L motor for Christmas....
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Old 11-18-2017, 01:27 PM
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V2Rocket
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this guy in ohio (mark, good guy) sells 2.5 engines for $500 or less.

https://plyhammersparts.com/
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Old 11-18-2017, 01:38 PM
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State of affairs as of right now... intend to swap the intake for a more attractive piece eventually (round plenum vs this box)

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Old 11-18-2017, 02:04 PM
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jderimig
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Where are you going to place the throttle? Is that an M90 (I assume from your previous threads).?
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Old 11-18-2017, 02:40 PM
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yes m90
currently aiming to stick the throttle on the end of that elbow next to the coolant tank.
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Old 11-18-2017, 05:25 PM
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odonnell
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I was admittedly doing this at one time, until Dimi ruined everything by sending me a ton of 951 gear for a price I couldn't say no to, so I built a 951 motor out of the donor NA block. And then I found a 951 in amazing condition (perfect 968 interior) for $2500 that needed a motor. 2 years later I honestly wish I had just stuck to my original plans. I love that 951 but it still has a ton of work left to go and I have no time. I would have had the '83 driving with a SC by now since it already has a standalone and I have a few friends who do fabrication/plumbing for a living. So don't assume that buying a 951 is always the preferred route.
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Old 11-18-2017, 05:36 PM
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I still consider a SC every now and then for my S. The plan is to build out a strong N/A 3.0 motor to swap in, but a supercharged 16V 2.5 would be a lot of fun too.
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Old 11-18-2017, 06:14 PM
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Augment is working on a similar concept. Low boost, good engine management and no IC at the moment. Still, should be safe as they made a turbod NA with 10,6:1 CR for drifting and it holds up! Obviously, it's not high priority for them either...
https://www.augmentautomotive.co.uk/...rger-dyno-run/
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Old 11-18-2017, 10:30 PM
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Interestingly enough I see this topic come up a bumch but never see much on the Speed Force Racing Solution. Why is That? Is it cost? Is it the different type of SC used? Or have not many people tried it....

here is the link to their solution:

http://speedforceracing.com/product-category/porsche/944/supercharger/
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Old 11-19-2017, 04:09 AM
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Dubai944
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Originally Posted by Giantviper View Post
Interestingly enough I see this topic come up a bumch but never see much on the Speed Force Racing Solution. Why is That? Is it cost? Is it the different type of SC used? Or have not many people tried it....

here is the link to their solution:

http://speedforceracing.com/product-.../supercharger/
Find my old posts on the subject. I have posted plenty of info on it in the past.
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Old 11-19-2017, 05:06 AM
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Originally Posted by Ish_944 View Post
Augment is working on a similar concept. Low boost, good engine management and no IC at the moment. Still, should be safe as they made a turbod NA with 10,6:1 CR for drifting and it holds up! Obviously, it's not high priority for them either...
https://www.augmentautomotive.co.uk/...rger-dyno-run/
Yeah they started a SC project 4 years ago !!

It should be a priority to sort as there is a market for such, it either illustrates how difficult it is to getting it working properly?, they take too much on and with little success, or both ?

R
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Old 11-19-2017, 11:19 AM
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H.F.B.
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Originally Posted by Giantviper View Post
Interestingly enough I see this topic come up a bumch but never see much on the Speed Force Racing Solution. Why is That? Is it cost? Is it the different type of SC used? Or have not many people tried it....

here is the link to their solution:

http://speedforceracing.com/product-.../supercharger/
^^^^ and complementary a rennlist posting dated 2002 --> https://rennlist.com/forums/968-foru...tml#post514556
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Old 11-19-2017, 11:27 AM
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I spent years and more money than I care to admit trying to perfect a SC on a 4 cylinder engine, granted this wasn't on a 944 but still an equally capable engine (twin cam 16V). After it was said and done, I was disappointed with the power even at 12psi, the 4 cylinder engine has to work extremely hard to turn the SC and overcome the parasitic drag of yet another pair of pulleys (SC pulley and tensioner) plus another belt. Performance was mediocre at best and reasonable only when you could wind it out on long stretches of road and pull it to redline, which was not ideal for everyday driving.

I eventually ended up pulling the entire SC setup with intercooler and custom piping and sold it, replacing it with a nice sized Garrett turbo and made more power at 5 psi of turbo induction vs a supercharger at 12 psi.

Thinking about it now, these are the same reasons Mercedes went away from their Kompressor 4 cylinder engines and now have turbo charged 4 cylinders in their place. In the mid 2000s, Mercedes had a Kompressor offering on their 4 cylinder, 6 cylinder and even V8s and it was somewhat short lived with the soon to come higher efficiency and more pragmatic turbos.

At minimum, you need a larger engine displacement with at least 6 cylinders to drive a SC.
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