Thread: compression ratio question

long story short the rod journals on crank in my gtir motor have been ground .020 and bearings are unobtainable also I think the rods are screwed up from being run with improper bearings the caps don't go on easily especially on cylinder 2.
fortunately I have a spare DE so I plan on rebuilding the gtir motor using the DE crank, rods, and pistons. this will obviously raise the compression so will it be ok running stock boost or will I be running the risk of detonating?

you should be fine, but i would use the det pistons so you get a lower compression ratio.

i found some bearings that are supposed to be 20 oversized, (cause without checking first i had my mech turn it 20 over) i think they were made by king but not sure ill have to find the site again. when i do ill post it up here or in my block rebuild thread.

thats whats in the motor now they are only for the 17mm de rods if you use them with gtir rods they don't line up properly

i do have that option, but I like the idea of raising the compression a bit to get better low rpm response

i missed the gtir part in your first thread. i wish these engines had been available in the US it would make parts shoppin so much easier

Why are the bearings unobtainable?

no one makes .020" oversized bearings for the gtir rods which actually turned out to be a good thing. I found one rod bearing had been spun previously so that rod is shot, but was reused when it shouldn't have also the head bolts weren't torqued properly none were as tight as the unopened DE that I just dissasembled, and two were barely torqued at all forutunately everything else was perfect.

I guess this will work fine, because the nay sayers would be more than excited to tell me why its a bad idea, and that hasn't happened yet

nissan oem are only made .005 .012 and .025 oversize in addition to the grade range

and other companies just call em one size fits all oversize, which may be fine for the US car companies, but if you want stuff to last like jap cars are known too all this stuff has gotta be tight and to spec. my machine guy works almost exlusively in US engines so he assumed incorrectly that .010 and.020 would be the standard oversizes available.


im no pro but this is my understanding of the whole bearing deal

I found one thing that may be an issue the DET piston skirt is clearanced for the oil squirters, and the DE piston isn't so now I'm not sure if I want to grind the DE piston or just use the DET pistons