924Board.org

[nazri]

i've got a '77 924n/a, totally standard 'cept for 15" inch rims and 60/205 wheels. i've got US$2-3k to play around with, and can get hold of another US$2-3k in 2 months. How do I get about 200bhp outta my tank? Any suggestions are welcome, unless u tell me to stick a jet engine in or something. thank you for your time

[eturbo924]

Check out Jons site
http://204.72.34.61/porsche/p924.html

For less radical and less hp check out my site and my projects.
http://www.geocities.com/eturbo924

You can also look at 924 Power tricks on my site. Many ideas there.

Eric

[swicks]

I have been thinking and came to the conclusion that the best way to get power out of a std motor would be to build it very carefully. Balance everything from crank to valves. lighten flywheel and pulley and maybe fit an electric water pump (must be worth about 2-3hp alone). Clean up ports and match all gaskets.

To get a bit more compression, I am going to look at shaving a bit of metal off the top of the block and taking a bit off the pistons to get clearance. A cam of about 270 degrees (std injection won't like anything more) should also help.

I haven't touched mine, but would like to hear from somebody who has done something similar.

Cheers

Steve in sunny South Africa

[TonyMechanic]

Swicks and Jon both have the right ideas. A well balanced motor can turn 9-10K RPM. If I were you, I would pick up a turbo head, have it ported & polished, and reworked by an experienced flow bench machinist. Then maybe do some fuel mods. I don't know if this is possible, or if its just the alkyhol talking. But I thought it would be fun to try and fit an EFI system onto one of these motors. I realize that its a TON of custom work, but the result would be sweet. I have a spare Mitsubishi Eclipse EFI system and I know that the fuel rail is pretty damned close to lining up to where the injectors on the 924 head. But don't go tossing a bunch of $ into that kind of project on my account. I'm probably just talkin out my backside

[ricomartinez]

Swicks, be careful about shaving the block. You're gonna reduce the combustion chamber volume. If you do that, you'll reduce the displacement. All else equal, with less displacement you will make less power.

[swicks]

Hi Rico,

I'm not thinking about taking a lot off, and it surely wouldn't affect the stroke as this is determined by the crank and not the block height. If I took some metal off the top of the block, then surely I could get to a decent compression ratio (10,1:1) or somewhere.

This would still alllow normal fuel to be used and I'm pretty sure the pistons would cope.

By the way. In South Africa, the parts catalogues give Audi 100 4cyl pistons a spec of 9,3:1 which is the same as a euro spec 924. kolbenschmidt make them and as the $ is worth about 12 Rand (our monopoly money) this might be a source considering. i don't have prices, but can get if you are interested.

Cheers

Steve (in sunny South Africa

[ricomartinez]

swicks,
I was being a smartarse. There are some here that believe if you make the combustion chamber larger, all else equal, the displacement becomes larger. So, I was using the reverse in this application.

I bought a thinner solid copper head gasket that should give higher than my 9.0 (for 81) CR. By some estimates from the seller and others, I should get a little better than 9.5. Can't really be sure until I get off my ass and compare the old to the copper before putting it in. I can then make a better estimate of the final CR. I'm waiting to get all ducks in a row (valve springs, cam, etc). There was an even thinner than mine, though, which I think should give a little better than 10:1. Definitely easier and cheaper than shaving the head or block. I paid $80, I think, but thinner should be cheaper.

[Zuffen]

Do any changes to the deck height, including altered headgasket thickness, and you will have to consider altering the cam tooth specs.

There is a min head dimension when you will start seeing a problem with timing and valve clearance.

There is a slight chamber in the the turbo head and then the pistons take up the rest of the volume.

The trick to higher compression would be custom pistons, cut for valve clearance and little else. Add studs to replace the stock head bolts and use a copper or aluminum head gasket. Keep in mind though the factory GTR headgasket is the same material as the stock turbo gasket.
The last version was 420 HP allegedly.

I haven't heard of O-ringing the head as is common practice on the 944. The 924 block, cylinder to cylinder wall is pretty thin.

The biggest improvement to a high compression engine is to weld up the water jacket passages on the head and block and to add a seperate head cooling circuit.

Then it is possible to apply a higher torque without worry of gasket crushing.

The two dissimilar metals is not a positive when trying to seal up the 924 engine, especially when looking a high performance applications.



_________________
Bob Dodd - 924turbo@cox.net
931 1982, 944 1982 euro, 924S 1988SE, 93 968 tip 06 Silver Cayenne S, 06 Black Cayenne S

I have Way too many cars, parts for the 931,944 and 951

[larso]

[AppleBit]

I have a $1000 dollar formula that will give you the most bang for your buck.

Pay $600 for the Electromotive DIS
Pay $300 for the Franco Cam Gear
Pay all the extra for getting it on your car...

Drive and drop your jaw...

Now that you did that- get a better grind cam and watch your car move even faster!



- Jon


_________________
Classic British Sports Car Restoration v6 + v8 Engine Conversion Swaps

Porsche 924 Wide Body LS1 Corvette 500 Horsepower Engine

[Roger Hall]

I would sell the 924 add the 6 grand and buy a 944 or a 931. My 81 924 is a great car but from everything I know the little Audi 1984cc will never be a good quarter mile engine no matter how much money you throw at it.

This is the performance area and I am probably not making any freinds, but when you weld the block shave the heads, add custom pistons its just expensive!!!!!! Horsepower for Dollars the Audi is just not a good return on your investment. Plus the Audi is reliable or it was before the 6 grand was put into it.

sorry

[swicks]

I agree with Roger. The Audi motor is pretty dead without a turbo, but it is reliable and by carefully balancing everything a doing a 'blueprint' there will only be a 10-15% increase in power. Do you want to spend that kind of money for such a little gain in power.

Rather gut the car and get it to 950kg - its cheaper!

Best of all find a kilometer speedo - then 60mph reads as 100kmh!

[Joes924]

I dont think Ill shave this head maybe the next,so msd6 rev control,274 cam[more like 270 schnieder said]port&polish,header,dial-cam,big bore throttle body.Then on to bigger and better things like a life for this 924 nut.

[ This Message was edited by: Joes924 on 2002-05-25 14:49 ]

[Geddy T]

Bob's right. Shave the deck too much and you'll be in the market for an adjustable cam sproket. One of our user's personal websites has a link to an article that goes all into this. I wish I could remember where I saw it.

[gohim]

Don't shave the block and head, you can't run 10 to 1 without advanced ignition management.

If you have to keep your 924 engine for some reason, buy the Piper Cam, and Timing Gear (Piper Cams in GB, phone 012333 500300), and convert to the exhaust from a 944.

According to an article in 911 & Porsche World, the camshaft and Timing Gear should yield an improvement of up to 12hp.

The exhaust change is fairly cheap, as it is a straight bolt-on with the exception of welding the 944 downpipe to the adapter flange from the resonator or catalytic converter (whichever you have), and should yield an improvement of between 8-12 hp.