I just got some CTR pistons (oversized) and i took them to the machine shop and i was wondering what should he bore the cyl.'s to also i'm having him mil the head and was also wondering what would be a safe amount to mil a stock b16 head with ctr pistons? TIA

 

Yes, bore and hone to whatever the oversized pistons are.

Do not mill more than .030

 

see the ctr pistons are .25 bigger so they are 81.25 and the machine shop guy said that if he bored them out to just 81.25 then they won't fit cause there will be no clearance... so i'm kinna confused

 

why would you wanna mill the head?

Don't tell me your not satisfied with what the compression will already be with CTR pistons?!

 

i'm not sure what the compression is with the ctr pistons.. i just figured since the head is off i might as well do some work to it....

 

well your compression will be about 11.0 with the head unmilled. I'd think twice about milling your head if you ever plan to run some big cams in your engine (skunk2 stage2/toda B's/etc) ....valve to piston clearance will become an issue.

just some friendly advice...

 

thanks cause' i was planning on changing cams soon too. like maybe itr or ctr's or pretty much any stage two cams...

 

so does anyone know what size to bore the pistons to? if the ctr pistons are 81.25? do you bore it out to 81.25 or a little bit bigger?

 

how about putting those CTRs into a B18C bottom and adding the B16 head, milling the head .01 and calling it a day. That should net about 12.2:1 and will be safe for JUN III/SK2/etc.

 

all i'm trying to do is RE-build the b16 that i blew when i went turbo... i'm not really trying to spend any more money then i have to...

 

Hi

i had CTR pistons fitted to myB16A1 last September like you i chose the 0.25mm o/bore. Any GOOD machine shop wil just bore the block to the new piston size.

As far as i can remember the only hick-up was fitting the new pistons to the conrods. The mating size is different so i also had to get the conrods machined for them to fit into the bottom of the piston

Hope this helps you a bit.

Craig

 

did you have it bored to the exact same size as the piston or was it a little bit bigger? what size did the machine shop bore it out to so i can tell the machine shop here... thanks

 

Yes they have to bore the block a couple thousandths bigger than the pistons for oil clearance. If it's an oem type piston use oem specs if it's an aftermarket use their piston to cylinder wall specs.

 

alright thanks that's what i wanted to know... the machine shop has been doing this for 30 years and he told me he's going to bore it out to 81.30 and the ctr pistons are 81.25....

 

Oil clearance??? Try again. It's called thermal expansion. Doesn't matter what size the piston is. All he needs to know is the piston to wall clearance. If he can't determine what to bore and hone the cylinder to after that he's a grade A, 100%, genuine, complete and total dumbshit.