i just got my 9.5:1 je pistons and eagle rods. ive heard the low compression may spool slower, and was wondering if a slightly thinner than stock head gasket would be wise? does anyone know the formula for computing compression changes with head gasket thickness? thanx

 

a lower compression will give you sluggish throttle response on a low boost setting, but IMO the whole point of running with a lower comp. is so you can run more boost pressure, do that and the throttle wont be as sluggish.

it sounds like you're building up your bottom end so it'll be able to handle the boost. what PSI are you planning on running? what about your fuel mgmt?

 

Agreed, getting lower comp pistons and aftermarket rods is the best way to increase boost, and increased boost means low compression is essential.

You should run a thick copper HG for saftey rather than raise compression for a turbo.

Low compression=happy turbo
High compression=all motor/Nitrous

 

I dont know about the benifits from a thicker head gasket (besides safety).
I read that as long as the stock head gasket's motion is controlled it'll be ok. motion control such as an interlock or mechancal barrier. does the stock gasket/block already have such a mechanism?

 

i disagree... there is no need for lower comp with todays technology... lower compression is yesterday's technology... u dont need it... stock or higher comp is fine if u tune it right and u WILL make more power

 

i probably wont be putting her together for another week or two, so i have time for some more research. im not exactly sure what boost ill run. i think ill break the new stuff in on no boost(disconnect i/c pipe) and then just start around 8psi and turn it up as needed. im going to be a little more carefull this time though, since i just nuked the stock rings. im still using a 8:1 fmu, 255 lph in tank, and RC310s. ill go standalone pretty soon, but i learned my lesson about doing too many things at one time. makes troubleshooting a pain in the ***. who makes different thickness gaskets? any websites?

 

The whole point of running lower compression is NOT so you can raise boost. You can raise boost with stock compression. The point of lowering the CR is to drop the cylinder pressure so you have more margin of error in tuning and it becomes SAFER to raise boost. Ever wonder why factory cars come with low compression? Btw, throttle response won't be affected by raising boost.

"but IMO".. please don't post your opinion if you're not sure whether you're correct. There's already too much bullshit information floating around as is...

-Mike

 

IMO, don't waste your time going with a thinner headgasket. Just run a stock headgasket. With 9.5:1 CR, it'll be fine for turbo. Unless you only plan on running low boost, then go ahead and run higher compression. For a street car you should be able to make plenty of power at 9.5:1 and decent tuning.

-Mike

 

i hope ur not talking to me... for one... this is not just an opinion...

 

My post was referring to blueshadow or whatever his sn is..

-Mike

 

uhh, IMO that's perfectly stated (had to throw that "IMO" in there)

Primary reason for lower compression is so that WHEN and IF detonation occurs, it is less likely to do damage...so higher levels of boost become safer. Im saying the same thing but it's worth repeating.

Is it okay to say IMO when you know your right?

And, by the way, a good way to help control head gasket motion under higher boost is with ARP headstuds...but, well, that's is of course IMO


[Modified by greyzone, 7:15 AM 12/15/2001]

 

thanks Greyzone,

the reason I put "IMO" in their is because Its My Opinion I dont want him to think that this is what everybody else thinks.

and another thing, IMO detonation is best controlled by getting a proper fuel setting. by that I mean proper tuning via a standalone, IMO a RRR, additional injectors, VAFC, etc is not the best way to do that.

 

and there's so few opinions arond here...

 

isn't that what I said!?! if you read my post I asked him what his fuel mgmt system was going to be. I wanted to make sure that when he raised the boost (as I suggested) that he had a proper fuel mgmt sytem to tune it.

so thanks for trying to flame me even before I had a chance to fully answer his question.

so you're saying that his car with 9.5:1 comp ratio, say @ 2 PSI @ 5000 RPM will have the same throttle response @ 10 PSI @ 5000 RPM?

 

And to answer IntegRated109's question,

like everyone said a stock head gasket will probably suit your needs fine, as long as it is seated properly AND securely.

bottom line... tune your fuel properly, if your engine detonates I don't think the size of the gasket will matter eventually it will fail. and like Tom said SlowTeg said with higher comp. tuning becomes more critical, tuning = the right air/fuel ratio = no detonation.

 

damn, didnt mean to start any fights.....thanks for all the info AND opinions. if i dont think its valad i blow it off, but i like to see different ideas. anywhoo, ill let everyone know what the end result is. i have a 200 dollar race set up with my friend(91 eclipse GS turbo) when we are both broke in. wish me luck,

 

are you mocking me? :D j/k didn't mean to get OT there, good luck with your project.

 

no mock at all patnah, ive been drinkin for about 4 hrs now, so excuse any mis-communication.

hey, i knew a girl from fairfield.....im from sonoma