Thread: SR20 piston ring end gap..

Im building a oem SR20DE 143hp NX and im having problem with new NTP first piston rings..

oem specs are 0.20-0.30mm.

used piston ring size is 0.23mm (ok but it's used).

new brand piston ring i got is 0.55mm, it's too big.

My question is if i can run good with 0.55mm first piston ring or i can get problems with compression.

Thanks.

Thats going to be too big for a oem piston. .55mm(.022") is about what the top ring would be on a forged piston in a turbo application. That is still on the loose side for a forged piston. I would contact gspec and get a oem set of rings.

i see..manual says limit is 1mm.. well i will talk with shop. they say std size is 86.00mm, ok, but block is grade 2, standar size is 86.10mm-86.20mm size..cylinders measure about 86.45-86.50mm, wear limit is 0.20mm so im still in std size, right?

another weird thing is second ring is bigger only for 0.08mm, so i think piston ring sets come with wrong rings, not sure at all! what do you guys thing?

grade 2 block cylinder bore information 86.010-86.020mm + .20mm = 86.21-86.22mm. You missed the zeros in the factory spec. You sure that bore measurement is correct?

did you push the ring down far enough in the bore when you measured the gap? It is possible you got the wrong rings with your pistons it would be the first time it has happened.

yes you are right..i need to assembly engine asap, according manual , end gap limit is 1mm, so i not sure if i'd have problems with 0.55mm gap, this will be a stock daily engine. got a NX including this engine from Junyark and everything looked stock, i think this engine was overbored ..

yes, i measured them correctly.

i did it wrong, wrong calculated, cylinders arent oversize, all they are about 86.05-86.07mm, anyway rings are bigger on gap but i think i'd install them .

I will check right now main/rod bearing clearance.

I have a doubt, what's difference between main bearing runing clearance and big-end bearing runing clearance? because main bearing are about 0.004mm-0.022mm and big end bearing clearance are about 0.020mm-0.045mm.

thanks for helps!