Lowest Compression



Ok, I've been purchasing parts for a turbo six, and I'm ready to swap heads as well. I'm interested to know which head to put on a '65 170 for the lowest compression possible. I was also thinking of doubling up on the head gasket. And while I realize that a seven-main 200 would be preferable for bottom end support, I'm wondering how much boost might I be looking at for a safe setup? I was guessing around 7 psi max.
8) since you are building a turbo motor, you can run up to 10psi with littel if any problems as the boost doesnt hammer the motor like a blower would. as for the head, use a late model 250 head as they have the largest combustion chambers. i would double p the head gasket, but instead try to find the thickest one available.

I did some numbers on the Compression calculator on our web page and came up with the following:

Stock 170, flat-topped pistons, .025" deck height, stock bore of 3.5" and stroke of 2.94", .025 OEM head gasket thickness, and OEM chamber volume of 52 cc = a CR of 8.7:1.

Change the head to a late model 200/250, D5XX or later, with a chamber volume of 62 cc and a composite type head gasket (Fel-Pro) with a compressed thickness of .050", all other dimensions the same + CR of 7.2:1.

What is your goal CR for your turbo set-up?

Adios, David
Considering I've already got a D7 250 head, I should be all set. 7.2 was around what I was shooting for. I picked up an intercooler off eBay, so that should help keep the intake charge temp down. Now I've gotta find the right turbo and seal up the carby. Thanks for the info.