The title says all, how much meat there is around the cylinders? It's safe to bore to 86mm in high horsepower application? Someone have experience?

 

What do you consider high hp? 86mm pistons will be fine, you cant ever really determine if the block will hold it or not. If you are searching for 800+ HP then a OEM brand new block with std bore custom pistons is your best best because the cylinder walls will be at their thickest then. It is common sense that the more a cylinder is machined and enlarged that the walls will be weaker.

 

why not just get a 4g64 block with 86.5mm pistons stock bore.

 

I did some searching & asked a few of the big name shops when I was rebuilding my 2.3 & everyone says that .040 over / 86mm wouldn't be an issue. I doublt it will give you any gains though. The motor I purchased was damaged & had to be rebuilt. It had previously been bored .020 over & had scoring on some of the cylinder walls so it needed to be bored an additional .020 over (.040 total). After checking arround I found that 86mm is gonna be just fine for most builds. Not sure it's a good idea for an 800+hp build but on a 500-600hp build I think it'd be just fine.

 

You can go to 86.5mm with custom pistons. That is about as far as you should go.

 

Ok, thanks a lot.

Is there anyone who does not recommend, and why?

 

You've done this before? 86.5? With an evo block?

 

Yes, I have one right now ready to drop in an engine bay complete with Manley I-Beams to 1000hp, JE Pistons, ACL Race bearings, ready to go.

 

Yes I know this is old as hell, i'm bumping to resurface old information. I have a .02 bore with damage, needs to go to .04. I'm looking to make around 750whp on a dynojet. Is this hp safe?