924Board.org

garyj19 · Joined: 04 Sep 2005 Posts: 226 Location: Connecticut

The motor in my 77 n/a is coming out next spring, and headed to the basement for a much needed rebuild. Originally, i wanted to keep the motor stock but lately i have wanted a little more go, so i want to take the upgrade route.

Just off the bat, i want to raise my compression ratio.

Does anyone know the ratio in my 77?

Can i simply fit in different pistons or is block and head resurfacing a good idea too?

and slightly o/t, but i will need motor mounts... are they NLA new?
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early 77 924 na

Grenadiers · Posted: Thu Dec 09, 2010 4:57 am Post subject:

There's a whole shatload of info on a sticky right above this post! To not answer your question, not sure on compression though.
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'83 944 Track car.
'88 924S Track car.
'89 944 Turbo
2004 Winnebago Vectra monster RV
2012 Jeep Wrangler
2014 Kia Soul
2001 Ford F350 powerstroke

Joes924Racer · Posted: Thu Dec 09, 2010 5:53 am Post subject:

Best thing, easiest route is take off some material on the block surface as you mentioned. Maybe search thru google for the correct amount,
its been thoroughly hashed over here. Cheers.
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1979 porsche 924 Na
1980 porsche Turbo 931GT Replica
Have u ever driven a turbo.

Rich H · Posted: Thu Dec 09, 2010 5:56 am Post subject:

Euro spec your car? You'll need pistons and a few other bits.
Factory spec 125 bhp in easy reach...
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

garyj19 · Joined: 04 Sep 2005 Posts: 226 Location: Connecticut

Yes, euro spec is what im looking to replicate i suppose.

And i looked in the sticky and although it had alot of great stuff , i didnt find too much about 924 n/a upgrades.

Anybody know of any horror stories about trying to push too much out of a stock bottom end?
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early 77 924 na

the_mad_electrician · Joined: 16 Nov 2009 Posts: 1073 Location: Central Georgia

check with ideola, he has custom pistons and rods if you are willing to spend a some cash he can give you whatever compression you want and the rods (from what I have read) are the weak link in the bottom end of the 2.0 engine. As a bonus the custom pistons and rods are lighter

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81 924 N/A

2004 Ranger "Edge"

2005 Mazda 6

924-76 · Joined: 05 Jun 2006 Posts: 1489 Location: Ontario, Canada

Euro pistons:http://www.924board.org/viewtopic.php?t=33870
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1976 924 N/A ROW SOLD
1980 931S
1981 931 Part car RIP

924RACR · Posted: Fri Dec 10, 2010 1:26 am Post subject:

9.5:1 CR is pretty nice (what we're running in the racecars); since it's out, you should consider having it lightened and balanced. Shouldn't be a problem to take 100 grams or so off the big ends of the stock rods (though aftermarket are lovely)... I think the stock rods are just fine in the NA, it's more of an issue with built turbos.

Yours will either be 8:1 or 8.5:1, depending (more likely 8:1 I think)... 9.5:1 will really wake it up.

Consider having the flywheel lightened too, but don't overdo it; some have reported problems with clutch engagement.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

garyj19 · Joined: 04 Sep 2005 Posts: 226 Location: Connecticut

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

If you have access to a machine shop who is willing to work with you, then I'd have the stock parts lightened and balanced and pickup a set of euro pistons to bump the compression ratio just a bit.

If you're thinking of going flat-out, then buy the lightweight rods and pistons and raise the compression ratio quite a bit more.

Then, you can drop a couple of grand on fixing the cylinder head with porting, stiffer valve springs, larger valves, lightweight followers and a more aggressive camshaft.

If you're really wanting to explore the limits of the 2.0L SOHC, then you can bore the block out to the max and have the crankshaft welded to increase the stroke to 2.2L or perhaps more. That's another couple of grand at least.

and so on....
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

garyj19 · Joined: 04 Sep 2005 Posts: 226 Location: Connecticut

Hahaha, budget build my friend! id love to do all that but the money is the issue... i do have access to a machine shop but id rather not.

Has anyone ever tried to lighten rods at home with a die grinder (going easy, of course), and balancing them to eachother with a scale? Thats kind of the route i want to take... I know i can do it i just want some imput
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early 77 924 na

924RACR · Posted: Sat Dec 11, 2010 4:26 am Post subject:

Yes, that's a perfectly acceptable way to remove the weight - or with a bench grinder, actually. It's just a question of how much patience you have to grind - that's a lot of metal.

But yes, balancing the pistons and rods with a grinder and digital postal scale will be just fine.
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

garyj19 · Joined: 04 Sep 2005 Posts: 226 Location: Connecticut

Cool, thanks. i can have patience for anything that saves me money! Now i have to wait until spring to do it all...

Hey this may sound dumb but ive never had the bottom end out of the car- Do i need to pull the trans/torque tube back to pull the whole motor out?
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early 77 924 na

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

Nah, just drop the front crossmember out and the bolts off the bellhousing and it should come out just fine.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)