cp piston ring install/orientation? help
 

ok i just bored my s14 sr20det 20 over to 86.5mm, i bought me some CP pistons and the instructions suck! no clear explanation on how the rings should be orientated on the piston, like oem 90deg of each other or different like wiseco?. also I am wondering the difference in ring gap from oem 86mm to the new 86.5mm? ive already googled it and searched with no answer, if anyone can help me out i would appreciate it!

I used oem orientation for my cp pistons

Also checked ring gap according to cp instructions, it's been a minute but I think they were all in spec didn't need to file anything down.

Hope that sheds some light

this is all that was included with the pistons, the link all the way at the bottom of the page

Piston Tech

thanks! i was wondering? because i had wiseco pistons on the motor before and the instructions on ring orientation was way different from oem, just wondering if cp instructions are the same? what size pistons are you running?

Use OEM specs for the orientation.


As for ring gap, on a turbo application, it is Bore (in inches) X .0055 = Top Ring Gap.

86.5mm = 3.40551in

3.40551in X .0055 = 0.018730305in

Top ring gap should be .0187in

The next ring is simply .004in to .008in over. So, shoot for .025in.

We just this on our SR with CP pistons and found that the gaping was not correct from the factory. So please, make sure you take the time you do this.

I replied in the other thread about filing your rings, but here^that guy seems to have helped you. Listen to him.

Sounds good man thank you! One more question which side of the piston goes to the front of the motor? The wiseco pistons are labeled these aren't

thanks! anyone know how the pistons go installed? which side goes to the front of the motor? or does it matter? my previous wiseco pistons were labled fwd-> these CP pistons are not? now if i have to file the ring gap i do not have a ring gap file, can i use a dermal with a metal cutting disk and just mount it in a vise and squeeze the ring gap around the disk and file that way? or file by hand?

If you file by hand, take your time. Don't take too much off, and keep checking with a spacer/feeler tool.

Ok so how does the piston mount to the rod which side faces to the front of the motor? Does it not matter?

I didn't answer because I'm not 100% sure. I have CP 8.6:1 for my KA-T but I can't exactly inspect them at the moment.

Hmm it's kind of weird that they wouldn't be labeled, even of it doesn't matter why not label any way to get rid of the guess work ?

Ok on #1 ring gap I have .014 / 0.35mm on my filler gauge so I must be at .018 /0.45mm?

Ok #1 is at .018 #2 I got a little file happy I guess and went to .026 which is ok

If it's giving you that much problem just let a machine shop assemble it.
That's not something you want to mess up on and think it's right.

na i got it done no big deal