924Board.org

AznDrgn

I'm building up a turbo efi engine and I'm trying to figure out how much power it's gonna put out so I can estimate the injector sizing and what not. Here's the setup I'm planning on:

'78 NA block and head (8.5:1 compression), O ringed head, ported and polished head, raceware head studs, BAE manifold, Haltech engine management or something similar, EFI running off the engine management obviously, ~T3 turbo running 15psi boost, intercooler, balance the lower end.

What do you all think this setup will push? I'm hoping for ~200 to the wheels and yes this will be on a 944 suspension and tranny. Any other suggestions besides take that money and buy another car?
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-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made

Peter_in_AU · Joined: 29 Jul 2001 Posts: 2745 Location: Sydney, Australia

really hard to estimate but 180 to 200 at the wheels is not unreasonable.

After all the money and hard work is done spend $100 on a dyno session to be sure your ignition and injector flow is right and that way you'll know for sure your hp and are less likely to melt pistons.
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1979 924 (Gone to a better place)
1974 Lotus 7 S4 "Big Valve" Twin-cam (waiting)
1982 924 (As featured on Wikipedia)

Learn to love your multimeter and may the search be with you

AznDrgn · Posted: Tue Mar 18, 2003 9:56 am Post subject:

ok so lets assume I can push 180-200 at the wheels, what percentage power loss are we talking about in the drive train? Also if anyone happens to know approximantly how much a late 924S ('86 on) with a bad engine, decent body and interior goes for please let me know. I'm thinking about using a 924S body for the project since it has the suspension, and brake upgrades I want.
_________________
-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made

Richard · Joined: 04 Nov 2002 Posts: 617 Location: Pacific N.W.

How about 17% loss in the drivetrain. That would mean 240 hp flywheel and I don't think so. You'd probably get 180 to 190 engine and 155 to the rear wheel. I'm basing this on gut feeling alone.

AznDrgn · Posted: Wed Mar 19, 2003 12:21 pm Post subject:

Damn 17% loss to the drive train wow that's a lot more than I expected.
_________________
-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made

Richard · Joined: 04 Nov 2002 Posts: 617 Location: Pacific N.W.

This is a most excellent site. Go to www.pumaracing.co.uk and scroll down to the article on transmission losses. I've learned alot from this guy. He has the theory down, backed by lots of experience.

jpab924 · Posted: Wed Mar 19, 2003 2:46 pm Post subject:

Azndrgn, one of these days I will also be following the same path you are going. a project like this will be more of a learning curve, and when all is said and done, the satisfaction of knowing you put something like this together will be worth it.

Luckily you don`t have an auto trans. The losses are even greater because of the torque converter. 15-17% is what most of the articles I have read say to use to calculate your eng hp.

Just a thought......maybe you can reduce some of the parasitic loss by lightening the flywheel.? It probably wouldn`t amount to much of anything, but every little bit counts.

AznDrgn · Posted: Wed Mar 19, 2003 3:15 pm Post subject:

Jpab, this project is mostly for educational purposes for me as well. I know that with the time and money I'm going to dump on this I could easily buy another car and upgrade it. The great thing about building this though is I will be very well aquainted with the system and I'll hopefully be able to understand all the workings of the engine more and be able to better understand some of these theories I read about.
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-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made

RageLtMan · Joined: 05 Mar 2003 Posts: 184 Location: Boston, Ma

you're saying that a supped up engine on a turbo pushing 15 freaking PSI is only going to throw out 155 at the wheels?! the 924S did that anyway, and it's N/A.

I've seen the dyno charts for a car similar to mine with a 6 PSI supercharger kit, and it pushes a lot more than that guys... and that's without the o-ringed head, without a new engine management system, etc.

BTW, if you have a 924S, why not work with the block out of that instead of a 2.0 from '78...?
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1987 924S 2.5L SOHC.

Lizard · Posted: Thu Mar 20, 2003 3:03 am Post subject:

924S uses the 944 block not the 2.0L Audi block if that answers your questions
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3 928s,

81turbo · Joined: 03 Nov 2002 Posts: 1065 Location: Oakland, CA

The 924S does not push 155hp at the wheels, It is more like 125hp at the wheels if you use a 15-17% drivetrain loss.

AznDrgn · Posted: Thu Mar 20, 2003 6:12 am Post subject:

RageLtman, the reason I am not using the 924S/944 engine is because I don't like the fact that it is an interference engine. From what I've heard I know there are advantages to it being interference but I'm trying to use that as a fail safe so I don't totally mess up the engine during the course of building and learning about it.

Anyone know if simsport has a website or something with the specs of his car on it? Looks like he is the only one who has gone anywhere near this route and I remember him saying he was pushing 200 at the wheels which is right about where i want to be
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-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made

Lizard · Posted: Thu Mar 20, 2003 6:14 am Post subject:

he has a site of what he has done, with a couple of pics but not too much, I will try and find it for yah
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3 928s,

Lizard · Posted: Thu Mar 20, 2003 6:18 am Post subject:

I think the site is http://www.geocities.com/the_924_site/super1.html but it is currently unavalible so I cant verify for u
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3 928s,

AznDrgn · Posted: Thu Mar 20, 2003 6:20 am Post subject:

thanks lizard
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-'87 Jeep Cherokee 4.0L 6" of lift 33" Super Swampers

-'83 Callaway 944 2.5L turbo, 300HP, 1 of 42 ever made