Head Gaskets
 

Well i'm going to replace the HG on my Supra. I'm going to use ARP Studs and a MHG. I'm just wondering why is there different size HG's? I was looking and there were 4 options. 1.2mm (Stock?) 1.4mm 2.0mm (Most people use?) and even a 3.0mm (why so big?). I have a 7M-GTE im going to machine the head to perfection and do it right with ARP Studs i jsut dont know what size to use? Oh after my rebuild i intend on running more boost and probly installing a 57 or 60-1 Trim Rebuild CT26.

Forgot something whats the difference between Stopper and bead Hgs?

you would use a different thickness for varying amounts of head and block material removed .
block and head have never been worked before ? you use less thick .. on your 3rd swipe at it ? you'd want a thicker gasket . it depends on whats been removed and whats left

First time the HG hasn't even gone im jsut rebuilding the engine so i thought i might as well swap the HG anyways. Wouldn't a bigger HG help the compression ratio thus increasing the amount of boost the engine will handle?

The thicker the HG the less the compression becomes. Higher compression = more power, however with more compression you run the risk of detonation, which is why you would have to use higher octane fuel. ddmcse is right, you normally wouldn't buy the HG until the machine shop tells you how many (mm) they have removed total from the head and the block combined, then you buy a HG to compensate
:dance:

The above said is true on Naturally Aspirated motors... On vehicles with forced induction, such as the Turbo engines, having a slightly lower compression may be beneficial because more compressed air can be forced into the cylinder... However, finding the right compression is key, and getting a thicker gasket is not the way to achieve it. You'd want different pistons for that