Differences in headgaskets

[gnavs]

I'm starting to source the parts I need for my headgasket and timing belt change and I'm getting confused when it comes to the hg's.  Can someone explain the differences between the 1,2 and 3 hole headgaskets?  Car is a 97 AAZ.
Thanks,

[macka]

the number of holes denote thickness. The thinnest being a 1 hole and the thickest being a 3 hole.

[gnavs]

ahh, that's good to know.  So would a 3 notch be better for higher boost applications? 

[Vincent Waldon]

Nope, particularly since you live in Calgary.  

The "right" headgasket is the one that gives your engine the designed squish volume you need for cold starts in the Calgary winter.  You pick the right thickness by measuring piston protrusion at TDC once you get the head off.

Changing headgaskets to change compression ratios and prevent detonation is a gas engine trick that doesn't particularly apply to diesels, since very little of the compression ratio is set by head-gasket thickness *and* diesels don't worry about detonation, by design.

[macka]

Nope, particularly since you live in Calgary.  

The "right" headgasket is the one that gives your engine the designed squish volume you need for cold starts in the Calgary winter.  You pick the right thickness by measuring piston protrusion at TDC once you get the head off.

Changing headgaskets to change compression ratios and prevent detonation is a gas engine trick that doesn't particularly apply to diesels, since very little of the compression ratio is set by head-gasket thickness *and* diesels don't worry about detonation, by design.

so selecting a hg during a chinook would be counter intuitive?