924Board.org

[jon_7248]

Well, I have the opertunity to gain a 79 924. I know it's not turbo but not much else. I have a feeling it has the audi 100 engine that i have read about. I want to pull the engine the first day of ownership and rebuild it. I would like to have high compression pistions and performance cam, but what else should I do apart from full rebuild? Anyone done nitrous?

Also, where can I get my hands on a rebuild kit for this baby? I do appreciate your time guys. thanks
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Jon

[924RACR]

IMO, a full rebuild right off the bat is a waste of time and money - $400+USD. Not without good cause. Get it running first, then worry about how long it's going to stay running. These engines will last a long time if properly taken care of. Get it running (which usually requires a new fuel pump and other attention to the injection, plus the usual plugs 'n wires), then maybe swap in a cam and tune it to run well, do a header if you're insistent. But get it running and reliable (no cooling issues, etc.) first. Fix any electrical gremlins. Fix the chassis - I guarantee the 25-yr old rubber's ready for replacement.

EBS Racing (www.ebsracing.com IIRC) has the re-ring kit for $400USD roughly. Pistons (new JE units) will cost you about $600/set, again from EBS Racing.

Check into Paragon Products (www.paragon-products) or 944Racing.com for chassis components.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

[jon_7248]

Thanks. I'll look at those. The reason I was going to do a rebuild was the fact that I know I wanted to change the cam, and pistons, and just figured a zero hour engine would be best since I was there anyway. Yea, rubber is a bit bad and replacement is in effect. Whats the specs on that engine?
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Jon

[epsylon]

I own two 924s and I am in your area. There is another San Anotnio board member bryanc as well. We should all get together sometime.
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'82 931
'78 928
Howell Henderson
South Padre Island

[CBass]

I don't think the factory exhaust manifold looks like a restriction at all.

If you can lay your hands on a used set of 924 Turbo pistons, they'll raise your compression considerably. I believe my car has ROW spec 8.5:1 pistons, which result in a CR of around 11:1 in my engine... Have to run it on 94 octane though 7.5:1s from a US spec '80 would be perfect for a streetable hot motor.

Add a good cam, from a place like Paeco or Intregal, the head, and then you should have some decent power... You'd probably want to upgrade the exhaust system at this point, I believe it was Vince who recommended the factory 944 system as an upgrade. The factory manifold is a very efficient design, and with some porting and sand-scavenging, would probably flow quite well.

If you do all your own work, and source parts well, this could be done for south of $1000.

[Joes924Racer]

Aleader has spoken man that was sweet, cbass
schneider regrinds [racing cams]arent as good a cam though there cheaper.
gave mine has a nice little power curve
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[Eturbo924]

CBASS Not that I think you don't know but if you put a set of Turbo pistons into a NA 1979 924 you are going to lower the compression and loose power.

If on the other hand you are talking about putting a 931 head onto a 924 block and then deck the block yeah you can get some good power increases but not by then putting the turbo pistons in it. You would have to take way to much off the block to get any decent compression numbers.

If you take the turbo head put it on a 924NA block and put higher compression pistons in that .... now there is a nice combination!

That is basically what I am doing this fall. I will dyno the car after all is said and done.

The NA 924 can get reasonable gains at reasonable prices if you can do the r&r work yourself.

Eric
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1982 924
1992 968
2003 C4S
Parts Parts Parts and More parts.
E-mail me for parts you need!
Drive Fast!

[CBass]

Eric: The 931 pistons have a higher compression height than the 924 pistons, to make up for the larger combustion chamber of the Turbo head. In a NA 924, the 7.5:1 pistons should make a good streetable CR. My car has 11:1 compression, and my thinking is it's from 8.5:1 931 pistons. The car needs 93/94 octane gas, and that can be hard to come by, so it's not all that good for the street.

The 931 head is a much better design, but you'd have to have custom pistons made to make up for the lower ratio. Compression gains from millign are usually pretty mild, there is only so much you can take out of an engine before you comprimise it's function.

Still, with higher compression and a cam, it would be easy enough to make up for the NA's shortcomings. It's still not going to be all that fast, but 160hp vs 110, you can really tell the difference. True, you could always buy a 931 to start with, but those are more expensive to buy, let alone to maintain. Besides, with a rebuild, you have a fresh engine

[924 turbo]

Just out of curiosity, how did you calculate the 11:1 number? Do you happen to have the CC size of the 931 combustion chamber, and the 8.5:1 piston? I'd be interested in those numbers if you have them!
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Jon Furst

[CBass]

I haven't opened up the head to measure clearance yet, but I will when I change out the cam, and I will soon have a 931 head here and I'll do a rough measurement with a moldable putty.

The 11:1 figure is an educated guess, based on the PO putting "high compression pistons" in it, the compression numbers showing 185psi for each cylinder, and the performance confirms it's not just a cam or carbon making it read that high.

I don't have the exact numbers on hand, but the math was done by my brother originally. I took a look at the compression numbers and specs for the pistons and I calculated teh volume of the 924 chamber, based on the deck clearance, compression ratio, and engine displacement. Using the specs someone had up here for the 8.5:1 pistons confirmed they were the right compression height, so I'm fairly certain they are ROW 8.5:1 pistons.

I'm considering putting some 7.5:1 931 pistons I am getting in, to make for a lower compression ratio, 94 octane gas is expensive I'd be able to check the part numbers and specs of the pistons then, and they'd be up for grabs.

[Joes924Racer]

I sure can tell the difference ive made..
it is a good idea when taking aprt the motor is would be best to
just boil it out and replace everything and throw in a p&p
and valve job with guides get a header, single thoat tb, a
good set a 8mm plug wires,msd ignition with blaster coil
and a rev control
, new cam with adjustable cam gear by replacing everything I just meant
bearings and rings. oh and get fuel injecter holders and
maybe a new set of injectors. the parts bin seems like a good cheap parts source.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

[CBass]

From what I've been reading, CIS injectors last forever... The only issue is there is a little filter actually in the injector, and this can get clogged, and easily unclogged by backflushing the injector.

I think the biggest hinderance to the performance of the 924 is it's low compression ratio. High compression and long duration cams go hand in hand, and that's the start of a beautiful engine.

[jon_7248]

alright. I know I am going to rebuild the engine and get high compresion pistons. p&p the thing and make sure everything else is good....thanks for everything guys
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Jon