Metal Head Gasket bore size question

[JohnRardin]

I'm planning on buying a MHG soon and I noticed the stock bore size (about 83-84mm) is less than the normal bore size on most gaskets (86mm). Woudn't it be best to have the closest bore possible to reduce the change in compression ratio and overall efficiency? I normally would research more before asking but I haven't been able to find much. Thanks Guys! Oh and by the way, which do you guys prefer... HKS, Cometic or the TMS gasket? Thanks!

 

[hvyman]

ComEtic and tms are the same thing. Both made by cometic.

All are good.

It really won't mess with compression for enough to notice. But one closer to the actual bore would be more material an harder to blow out.

 

[JohnRardin]

Very true. I forgot about that helping the seal. I was mainly thinking... wouldn't a 84mm gasket have a more efficient combustion than a 86mm because the gap would change the flow (aerodynamics) and size of the combustion chamber (compression ratio)? I know it's a small difference but spread across all 6 cylinders I could see it making a difference overall.

 

[hvyman]

No it's not enough to worry about. And compression numbers are based on each cylinder.

 

[suprarich]

There are 84mm 7m gaskets available, and it is nice to have the extra material between the bores.