Max bore of 88mm is it safe??

Big P · Post by **Big P** » Mon Mar 03, 2008 9:41 pm

Just looking to get some more info here. Was looking at daftarts site and saw the wiseco pistons. They make them to a mzx bore of 88mm. I know that the factory bore is 86mm. Would the structural integrity of the engine block be severely compromised if overboring to this extent? I am only asking because boring out the cylinders to 88mm will give me an engine size of 2.4L and help with power output.

exist3nce · Post by **exist3nce** » Mon Mar 03, 2008 10:03 pm

If you are only looking for 300 crank HP, I would say its probably not worth it to bore it that much.

kinkyllama · Post by **kinkyllama** » Mon Mar 03, 2008 10:28 pm

exist3nce wrote:If you are only looking for 300 crank HP, I would say its probably not worth it to bore it that much.

+1. I'd be worried about the reliability with boost.

Big P · Post by **Big P** » Mon Mar 03, 2008 11:47 pm

Ok that's cool. What are the more popular overbore sizes? .5mm?

GsiTurbo · Post by **GsiTurbo** » Tue Mar 04, 2008 12:11 am

The standard max bore is +1mm... anything more than that and you will need to start looking at custom parts. Personally, especially if you plan on running boost, I would keep it within 0.5mm. Any more than that, and chances are the cylinder walls will start becoming thin and may distort with the pressure from boost.

Big P · Post by **Big P** » Tue Mar 04, 2008 12:40 am

Ok thanks. .5mm is what I had figured so hopefully it won't need to go any bigger when I get it to the machine shop.