Overbore size??????

[donniekak]

Real simple, .5mm over pistons would be 91.6 mm right. What do i tell the machine shop to bore my cylinder to 91.62mm?

[jbavousett]

Just tell the shop that you want to bore it out. I went 50 over.

[RealMcCoy]

Originally Posted by donniekak

Real simple, .5mm over pistons would be 91.6 mm right. What do i tell the machine shop to bore my cylinder to 91.62mm?

Most machinists will want the pistons in hand to mic, and hone the bores accordingly.

[magnafsb]

From stealth316.com
Belongs to Jeff Lucius
The stock bore is 91.1 mm (3.5866"), and Mistubishi provides factory pistons up to 0.040" over factory bore. I had my engine bored 0.050" over stock, which increases the bore to 92.38 mm for a displacement increase of 84 cc to 3056 cc from the stock 2972.3 cc. This reduced average wall thickness to about 0.238-0.250" (acording to Joe's and Ray's measurements; I do not know if my engine builder sonic tested my block). After twelve thousand miles I have not encountered any problems, but the increase in wall deflection and stress may reduce the durability of the engine somewhat over the long term. Some of our alloy-steel block 6G72 engines have been bored 0.075" over stock resulting in a 93 mm bore, which increases displacement by 126.1 cc to 3098.4 cc and reduces average wall thickness to 0.213-0.225". Ray Pampena bored his block 0.100" over, which increases displacement 5.67% to 3141 cc (see the table below for overboring comparisons) and leaves an average wall thickness of 0.200" for his engine.


More can be found here:
Stealth 316 - Piston Upgrade Guide

[Sin'sVr4]

mine is bored .30 over. Most machinest( the good ones and reliable ones) will want your pistons in hand.