i know for sure that a thicker head gasket will lower compression and vice versa. my friend says it doesn't do anything except waste your money. well we made a bet for 500 dollars and all I have to do is buy the gasket and do a compression test. Could I be wrong? He's attending a auto school and he said someone else asked the same question and the instructor said the gasket doesn't do anything except seal. BTW i was planning on the toda 1.5mm gasket.

 

you're going to loose!

it lowers the compression RATIO by a few tenths of a point at most. it does not affect the compression pressure measured by a device that goes in a sparkplug hole. that is affected by ring seal, rpm, cam timing, cam lift and valvespring pressure in that order. similarly you would not see any change in a leakdown test.

 

guess the evo and I are gonna run for the border then =D

 

depends on what type of headgasket you are talking about. You are technically correct. Running a thicker headgasket will decrease compression- hence why many companies sell thicker headgaskets for turbocharged applications.

This may be considered a 'spacer', but with a copper headgasket, the head needs to be o-ringed for a proper seal, and the only other thing that goes on the copper is a spray.

Real spacers are usually if not always laser cut steel, and utilize a stock headgasket on either side.

Go ahead and bet. Any turbochargeder-knowing mechanic will agree with exactly what i said.

http://www.eiptuning.com/eip/coppergaskets.html