Hi

Im looking to boost my stock ITR, Just wondered how thick cometic gasket do i need to lower the compression to say 9.5.1 ish.
( did ask the queestion a few years ago didnt get much/any feedback)

Also will the cam timing need to be adjusted with the increased thickness?

Anyone with experince on this issue, help would be much apprecaited.

Thanks

 

You don't need to lower the compression at all in order to turbocharge the type R engine unless the tune of the car is just incomplete.

With today's innovations there is no real reason to lower compression from 10.6:1 or 10.4:1 as long as the engine itself is sound.

 

do not lower compresssion

 

well the thing is with stock 11.1 compression i will only be able to run about 7 psi or evven less. I was thinking of lowering the compression and pushing it up to about 12 psi- ish.

I am intendiing on building a block as i have a GSR bottom end in my garage but i intend on sleeving etc so i dont really wanna hold on until all the parts arrive and get installed etc last time i waited for everything to arrive my car got totalled and all the parts sat around or got sold eventualy

So its why i was thinking about a thicker headgasket to get things moving..

 

i was just about to start a new thread but good thing i found this. i am also thinking about lowering the compression on my stock gsr. im trying to get about 300 to the wheels. i dont want to go past 12 psi of boost. hopefully 12 psi will get me more then 300hp. but i want this to be a reliable car as well.
so my question is what thickness to i need to lower my compression down a bit to make everything safe. i was looking on ebay for the cometic head gasket and i got confused a bit on the numbers. i think i need a 81mm bore but i dont know about the rest. can someone give me advise on what kind of thickness i need for my stock 95 gsr?

 

Guys. Get out of this PSI fascination. This is where you get into trouble when it comes to what you're trying to achieve. Stick to the power goal. On the GS-R the same logic applies, no need to lower compression. There are plenty of setups on this forum that keep stock compression, stock head Gasket, etc, and make over 300whp reliably. Get this stuff out of your head. Even if going over 350-400whp, the rest of the stock engine won't take much. The headgasket would be the last thing you need to worry about.

 

k that is great i dont have to spend 100 on a gasket. but arp head studs wont hurt right?

 

If you like your head lifting you can pass them up.

 

I was under the impression that one of the reasons the rest of the parts will be strained heavily is due to the high comp of the engine type r block.

Im hoping to achieve just over 300whp initially on a GT3071r, i dont know if that will last on a stock block ITR for very long. I want it to last around a year at least before i come to change the bottom end.

its why i was thinking of lowering some of the strain on the bottom end by dropping the compression with a THICKER headgasket.

 

A thicker gasket won't lower it much at all. If you want to do anything to help it last longer just do a factory rebuild on it. Otherwise there are plenty of GSRs, ITRs and LS blocks out there that are all stock easily running 300, 400 or more no problem and have been for awhile. If your engine is healthy and you have a good tune then you'll be just fine.

 

here is the tricky question. lets say i dont buy a new headgasket and i buy a arp head studs and torque them to factory specs. can i do one head stud at a time so i wont have to pull my head off and change my gasket? or does that sound like it would mess things up.

 

Torquing them to factory specs defeats the purpose of the head studs. Go by ARPs specifications. There is a specific order to perform the service in.

 

Oh that's what I thought. So wat is the specific order. Where can I find that

 

helms manual maybe?

 

no headgasket will get you that low youd have to make a head spacer like vdubs do and the easiest way to make the power your after safely is tuning!! no need to worry about headgasket i always use oem honda but tuning is wat you need go to a well known tuner also the gt30 will easily make that on probaly 9lbs i make 308whp on 7lbs with a little bigger turbo

 

Wrong. Cometic makes a hg that will lower your comp by 2 full points. Is that the best route? Probably not, but they make one. I have a hg in my engine now that lowers the comp by 1 pt and it is and has worked fine for ~4 years now @ 325whp. I understand that its not the best way to do it but when I put the engine together it was my best option (cost wise) so I did it.

In the end:

1) Boost pressure is NOT a goal to set. Power and where you make the power (depends on what you are doing with the car, i.e. drag or auto x).

2) You can lower the comp, but it is relatively moot if you have a good tuner. The tuner will know the comp and understand what he/she needs to do with the timing to get the engine to make the power desired.

3) Please take a look around before you spread info (more accurately mis-info). In this case it's relatively harmless, but in other cases it could coherce someone do a lot more work than necessary or even influence someone NOT to do something he/she should.

 

this is a great point it all comes down to the tune. if the tuner recommends a lower compression then you should find a head gasket. if he doesnt then its a waist of money. i am gonna do head studs but where can i find the torque specs they should be set on a turbo motor?
also i asked this before. can i do one headstud at a time without taking the head off including fluids?

 

I read an article on hondatuning.com (look it up if you dont believe it) where all they did was take a stock B16 and switched the pistons for arias 9.1:1 flat top pistons, AFAST FMU, and they tuned the crap out of it working there way up to 24psi 507hp and 300+ft/lbs. Everything besides the pistons was completely stock, even the head studs, bearings were reused, and the motor was an average street raced b16. So in conclusion I personally opted to use the cometic .051" hg because I already bought it so really didnt hurt much but if you dont need it then use the money to get some nice pistons. Good luck with the builds.