I just picked up my b18a yesterday and i am going lsv with it. I am wanting to put in p30's. The motor has 175,000 on it but it appears to be very well taken care of. i have researched into this and i know that the p30's should fit without modification to the cylinders/rods. I also researched that after honing the pistons should still fit properly. My question is, since the motor had so many miles on it, is that going to effect the proper clearence of my pistons to my cylinders?

 

Only way to know is to put the piston in there and check the clearance.

I just had my motor build and the machine shop owner was trying to pressure me to go over sized pistons so he can bore the cylinders to make sure they are round and not oval. My block was a JDM block, most of the time JDM motors do not have a lot of miles. So I was able to retain stock bore with a slight hone

 

With that kind of mileage on the block, I believe in only doing things once and doing them right. Have your block bored to 81.25mm and get oversized pistons, re-hone the block, new bearings etc and enjoy the brand new motor with essentially 0 miles.

 

Yea JDM motors dont have alot of miles, they have alot of kilometers lol but seriously unless the mileage is documented and verified I wouldnt trust what they say about "low" mileage.