what is the max possible safe bore for the 4g63?

 

88mm is probably the biggest and safest. good luck.

 

im from the honda world so i dont know much about the structure of the 4g63 block.

is 88mm still safe for high boost and streetability? does anybody have a picture of a 4g63 bare block?

 

88mm seems a little large to me. Do you have direct knowledge of that? That would be like a .118" overbore and the most I've ever heard of in a 4G63 is .060" (almost half what you said). only sells 4G63 OEM pistons at .5mm and 1mm oversize, so take that FWIW. I thought the .060" over was a lot when I heard about it, but I would definitely get some second expert opinions on that 88mm

If you want safe and reliable, I would stick with what is safe and reliable: .020"-.040" overbore or a stroker kit if your goal is to add as much displacement as possible.

 

.060" sounds about the highest Ive seen

9:1 0.20" J&E's are nice...

 

Anybody find out yet?....lol. Its only been4 years.
I may do the .060 due to a blown piston that damaged the block wall. Any input would help.

 

There isn't an answer. These are sand castings and they will vary.

 

0.040" over is probably pushing it.

 

most people do .020 over

 

Mitsubishi recommends no more than a .040 overbore (86mm). I have head people say you can push things to .080 (87mm), but certain compromises come with that.

 

86mm should be the max you can overbore,I have over bored to .060 though,but thats pushin it!

 

86 is about it on anything with 800 or less.
If its a 400hp rebuild maybe 86.5
if your shooting for the 1k plus stick to 85 or switch to a 64 block.

 

Well, if anyone has does do a .060 over let me know. I am a cheap bastard and have 4G64 wisecos and don't want to spend money on new 4G63 pistons... My 64 block is pretty much shot and has been sitting too long. Since I got a 63 might as well make a stroker huh?

 

 

I agree with most others... 86mm will be the max for a well tuned daily with mild-high hp