How Far Can I bore A 5S Block Out?

[Joshstix]

The 5S crank is a good thing, it's forged steel and has significantly larger big ends than the 3SGTE crank. The rods don't seem to be that great but generally you'd get the 5S crank ground down to 3S big end diameter anyway, possibly offset grinding for greater stroke, then use 3S rods.

[The Real Roadrunner]

grinding the crank down to suit the 3s big ends is a good thing as it lowers the bearing speed, but offset grind the crank to give more displacement will give you stupidly high piston speeds if you try to rev it over 8000rpm.
you would be better off using the standard stroke 91mm and getting custom pistons made with a shorter pin hight. that way you could run a longer rod which will make the engine a bit more effficient between 6500-8500rpm as the piston is at tdc a little bit longer.

the piston hight i want to run will only let me run a single comp ring and an oil ring.
rering every 10,000 damnit why didnt i go 1j

[-Totenkopf-]

Hey Roadrunner, this is exactly what I did. I got customs pistons and rods made. Custom wrist pin height and I think my rods ended up being around 146mm long. Could have probably went a little further, but didn't want to push my luck. I kept the 5sfe big end though (Custom pauter rods to fit it). I wouldn't think there would be much difference though. Small big end may lower bearing speed but larger would allow larger surface area for pressure dissipation and what not. I think the net result would be miniscule? I never really thought about it until now though.