CP piston review

[KEMP]

the CP pistons from RaceEngineering do have the oil squirter notches, correct?

my machine shop F'd up and did not balance my pistons once they notched the wiseco's. Needless to say, they are no longer my machin shop.

long story, but in short, the lighter side of the piston was dragging the cylinder wall, bending the top ring like a squeegy, causing the top ring land to stretch out on that side, ill try to post pics this week.

any ways, do you guys recommend the CP's over other pistons for our cars? and they are direct "bolt on" no machining required?

[sjbsuperman1425]

from everything i've heard they do have the notches

not sure about the machining.

[bentvalves]

dude, too much boost and not enough fuel beat the s*** out of your pistons.

its not because they were notched and not balanced.

balancing them after notching only ensures they weigh the same amount.

[KEMP]

if you saw the pistons, you would think different, its on one side of the piston, and its on the side the notch was taken out, they are off balnce enough for you to see when you hold the rod upside down the piston leans hard to the otherside.

the ring looked as if it may not have had enough gap, and went u and down in the top ring land, causing that side of the ringland to stretch.

i took it to another machince shop, they told me the signs were not of det, or lean conditions, it was on the side, not the top, and they, just by looking at them, could tell the balance issue caused it.

it was dragging on the cylinder wall on one side(side of notch)

that sid of the ringland(one side only, on every piston) looked like this > from the side instead of the otherside whic was [

the symbols are not reresenting scale, just showing what they looked like.

even the machine shop that did it, said it wouldnt happen from either balancing(which i think is BS) nor the lean condition. they think there wasnt enough gap in the ring so it closed up and touched eachother causing the ring to max out and stretch the ringland by dragging the ring.

either way, i know it was they're fault, but how can they not take resposibility for it, even when they said its the ring gap, that THEY gapped.

they are trying to say they can't do anything....

[bentvalves]

10-4, that makes a bit more sense explained in depth.

[bradt]

Yes, if material is removed from ANY part of the rotating assembly, it is imperative that it be balanced.

[float_6969]

CP's drop right in w/o any modification needed.

[KEMP]

looks like ill be goi9ng with 84mm 8.8:1 Cp pistons.

found them for $488, from race engineering. I'll be ordering them today, and hoping for a refund from the machine shop, maybe i will threaten to take them to small claims court.

but i know this is not my fault, and the machine shop, Performance Motorsports, which i'm using this time, assured me that what happened to the pistons was not my fault. I figured once i explained it in more depth, you guys would understand.

these are the pistons i am getting.http://www.raceeng.com/p-9155-....aspx

[ILOVESILVIA(S13)]

Cps drop right in w/no problem. Work great for my CA.

[boost_boy]

Yes, if material is removed from ANY part of the rotating assembly, it is imperative that it be balanced.

Not necessarily; and especially the pistons. I've seen pistons scorched-up one side of the cylinder before, but it's not from material being removed from the piston. Bad machine work such as a bad re-bore or incorrectly installed components or even worst an overboosted engine with too much timing would cause this condition on the intake valve side of the pistons. Just a few things that can cause your condition.

Dee

[niscort]

Must say its the first Ive heard about pistons having to be balanced about the gudeon pin.

I would be having the block inspected as the cause of the problem rather than the pistons which seem to have ended up as the result... Would hate to see the same thing happening to the new pistons