40 Thou Over Problems?

[ajohnston]

i have a rb30 bottom end with the following mods.

arias forged pistons 40 thou over 9.0 to 1 comp ratio

spool conrods

arp rod bolts

arp main stud kit

rb26 size arp head bolts

rb26 main bearings with annual groove

reground crank grub screwed balanced etc

rb26 piston oil squirters

oil galleries grub screwed

line honed

internally deburred

basically everything you could want within reason

im just wondering if there will be any problems running around 2 bar from a gt40 or gt42 on a rb30 block that is 40 thou over any info would be great also any idea what the max amount of power this bottom end should be able to handle the head is cnc ported etc so flow isnt a problem.

Edited July 24, 2010 by ajohnston

[Gerg_R31]

plus 20's 30's and 40's arent an issue if they are honed properly with the correct clearance set by the piston manufacturer,

if your worried, grout fill the block, get an ultra sound check on the bores to see if they are thick enough, plus 40s are a big over size but doesnt mean the engine should be nursed, ive seen some rb blocks go to plus 60s before they have to be resleeved

people do worry about going to plus 40s as in some motors its the last oversize, but it doesnt affect the performance, just means if you break it, you will pay more to fix it next time

and some one off piston designs are only in a plus 40s

[blind_elk]

The problem won't be related to the (over)size of the pistons, I see more of a problem running that much boost at that C/R.

[ajohnston]

its not on pump fuel