switching to a 2mm mhg

[datz280]

I am building a turbo engine for my 77. I am going to go .040 over and use forged pistons. I am thinking a good cr would be around 8.5 for off boost performance and still enable me to up boost later. I will be using MSnS to tune. While I am tuning it sounds like the advice is to use a stock head gasket (1.25 mm) and if you detonate it is the part that lets go.

 

After I have the tune down I would like to go to a MHG. The 1mm is expensive and hard to find. If I use the 2mm then the CR would drop to around 8.0. What are your opinions on this, or should I just go with a 2mm MHG to start and be careful with the tuning?

 

Mike

[thehelix112]

Why do you want to go to a metal head gasket? If everything is built (decked, torqued, retorqued etc) correctly the only time a good quality OEM gasket will let go is if you have detonation. In which case, its either the gasket, or eventually the piston.

 

I don't see the advantage?

 

Dave

[datz280]

head and block will be checked for straightness and both decked to provide a clean new surface.

My desire to use a MHG came from recalling that others were staying away from composite gaskets. Re-searching it seems that using the composite brands are ok and they are letting go when you run lean and detonate or from a matting surface that is uneven or warped.

[savageskaterkid]

I'm pretty sure that you compression would be lower then 8:1 with a 2mm head gasket. If you want a decent compression, and your spending all kinds of money on machine work, you may as well go with the 1mm piece. Or use the 2mm piece and remove layers.