I am at 30 over and am doing a rebuild-refresh. It looks like the bores might need more then a hone. I know it is not recommended but Tanner has a 399ci which is a 50 over ( I think) and engineermike (?) has a 385ci and they both make great power.

Has anyone ever pooched an FI motor with a 40 overbore??? Can I get away with it at 600rw?

 

you shouldnt have any problems. There are a few people who are 60 over around here so I wouldnt worrry.

 

I'm at .040 and no worries here.

 

Make sure there is enough material to clean it up. I am at .030 and was told .040 wouldn't be enough to clean them up.

.040 is pretty easy - at 600 hp if everything else holds the block will be fine.
.060 takes luck and a good block

 

Taner boseneli's 8.96@157mph car is still a LT1 block half filled that is .050 over he has no issues . and he hits it with a 400 shot.

Jay

 

Be careful. From builders I've dealt with the LT1 can have a lot of core shift in the casting process. Some better than others. I won't put words in anyone's mouth runing +0.050, but if these guys are serious they have their blocks sonic checked to make sure cylinder walls aren't below minimum. You are guessing unless you have the block sonic checked. I think block fill is a good idea regardless for bore stability.

-Scott.