109 Block max bore ?

[stage169]

Just getting started on a turbo motor for my 77 Buick SkyHawk. Was wondering if .040 additional bore is to much? Also I know that S&W race cars sells a front motor plate for the V6. I understand that I will have a lot of fab issues but was wondering if there are any GN's out there with a front motor plate. Thank's, Brian

[kenmosher]

Depends on the block ... some have worse core shift than others and 0.040 over can cause thin cylinder walls and overheating issues/bore wear/bore out of round.

It is generally recommended not to go over 0.030 unless you sonic check the block. Of course, take this with a grain of salt ... if we're talking about a lower boost street only motor that isn't stressed, then it'll be fine at 0.040 over.

[stage169]

I was told this motor was in an 11.30 86 GN. I am shooting for mid to low 10's with my SkyHawk. My car should not weigh anymore than 3k lbs. Thanks Ken, Brian.