Can anyone tell me the what size head gasket or decompression plate would be needed to lower the cr on a focus st170 to create a st170 turbo. There's a guy on ebay selling a st170 turbo with stock pistons and he says he used a 3layer head gasket to lower cr and its running 14 psi. But I thought the st170 head gasket was already 4 layers thick and the stock zetec was 3 layers? Also the Americans seem to be safely turbo charging stock st170s ( svt turbo in America) but I can find how they are doing it Wether it's a cometic head gasket or decompression plate? Any help or advice much appreciated cheers

 

Could use more than one headgasket

 

Focus rs 1.8mm thick genuine ford head gasket for frs that's had a head skim. ?

 

as above i am in the middle of doing the same thing....burton sell a cometic gasket 1.78mm but its on a 3-4 delivery as of yesterday, going to phone ford later.

 

All I could find was a Pec Athena head gasket that was 1.6 thick I will ring ford and find out if the 1.8 frs one is still available.let me know if anyone finds out the part number for it cheers

 

I got one a few months back for mine. Do a search for the part number as Ford's will have no idea what you're on about. There system doesn't show the thickness.

Not cheap though. ..around £142

It drops the cr a little more when you use a blacktop head. No need for the st170 head with a turbo. You will run out of luck before you run out of gas flow.