I've done some searching on this and cant find too much other than "it's not the right way to achieve lower compression." So maybe someone can give me some concrete answers in this post.

I bought a semi built d16 about a month ago. It has Arias 10.5:1 compression pistsons in it. I bought it with the intent of getting some rods, cleaning up the motor, doing maintenance, etc and then turboing the motor. But, I live in the midwest and there is no one around here that I trust to tune 10.5:1 compression and a turbo. So, i was thinking of getting a thicker headgasket to lower the compression a bit. From what I've been reading a 2mm hg should lower me about .4-.6, which is about what I'm looking for. Now, what are the negatives to doing this. Should I just say screw the pistons and get new lower comp ones while the motor is in pieces?

I like the idea of 10:1 and 10psi or a little more on my little d motor, but I'd prefer to not blow it up. My goals for the car are about 250whp on high boost setting. Nothing crazy now, just a low 13 second car that I can daily drive until I buy another car.

TIA for any help.

 

You sure the compression is actually 10.5:1? When I bought my SRP pistons for my D16Y8 they were supposed to be 10.5:1. When I calculated out the C/R myself it came out to be more like 10.1:1.

 

im kinda in the same place you are. im running 10.5:1 right now. I was thinking about getting a .120 head gasket from Comstic and it would have dropped my compression from 10.5:1 to 9.2:1. Also like you i wasnt sure what it would do.

 

drop the compression unless you have 93+ octane available.

 

I know I need to drop the compression. Thats not what im asking. I'm asking if dropping the compression using a thicker head gasket will be detrimental to the motor. And I have 93-110 octane readily available.

And I'm not sure if they are 10.5:1 or not, just going by what arias stated. How could I calculate this?

Also, any other answers out here? TIA for any help.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JapTendencies &raquo;</TD></TR><TR><TD CLASS="quote">I know I need to drop the compression. Thats not what im asking. I'm asking if dropping the compression using a thicker head gasket will be detrimental to the motor. And I have 93-110 octane readily available.

And I'm not sure if they are 10.5:1 or not, just going by what arias stated. How could I calculate this?

Also, any other answers out here? TIA for any help.</TD></TR></TABLE>

http://importbuilders.com/compression.html

compression is compression. it wont be detrimental. Now, flat pistons yield better power than domed or dished pistons but that's a different story. (Less surface area)

 

Same boat here buddy

Ive got some SRP 9.5:1 for my A6 ( or so I was told 9.5:1) and my head is also milled .040, compression is in the mid 10's but Im not sure if I bought the pistons knowing the correct c/r

They are also .020 overbore, and my block was just honed and **** for stock bore so I dont know what to do

Is there any way to calculate compression form scratch with the pistons sitting here in front of me?

I do have a digital Vernier

 

Using thicker gaskets to drop compression can be counter productive, as the quench areas in the chamber become less effective. More detonation can occur as a result.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Dr Pooface &raquo;</TD></TR><TR><TD CLASS="quote">Using thicker gaskets to drop compression can be counter productive, as the quench areas in the chamber become less effective. More detonation can occur as a result.</TD></TR></TABLE>

Ive heard a lot about this as well. But I also here that a lot of people have been running very thick headgaskets and have had no problems. Is this more of a problem the thicker the headgasket? Or does it not matter? And how does this cause more detonation? Sorry for the noob question, but the first I ever heard about quench areas was two days ago when i started searching for this stuff. Still kinda confusing. TIA for any help.