vr4 pistons compression test

[redzone]

reason i went to forged vr4 pistons is because at 18psi my cast hypertec pistons didn't really like it too much...... ended up being able to pull chunks of ring lands out of 1 piston and the other had a few cracks in the lands. 7,500km old motor too!

i do also have a ported head, i think with some combustion chamber smoothing, and roller rockers with a billet cam from RPW. :) which would affect readings, but i was mainly after a vague indication.

i was mainly doing the comp test to see if cylinders were even, but i was a little worried when comp came out so low. but not now :D

thats a tune related problem, not a piston problem, your new forgies will do the same if you dont retune it properly..

[oggy]

^^ i had thought about that posibility too, but car has microtech LT-10s, MPI, direct fire ignition etc etc. had a full tune on 15psi. but i would say that tune definately played a part in it

[S0LJAH]

^^ i had thought about that posibility too, but car has microtech LT-10s, MPI, direct fire ignition etc etc. had a full tune on 15psi. but i would say that tune definately played a part in it

car can have all those things and still have a shit tune on it that wrecks ringlands

[oggy]

yeah, but what i mean was that the car was fine on 15psi. it was bumping it up to 18psi and bringing boost on alot earlier/harder when it blew.

not trying to argue or anything, as i do think that the tune played a roll in it, just not sure how much.

and yes, car has been re-tuned LOL

[redzone]

it doesnt take sherlock holmes to predict that an engine running 18 psi thats tuned for 15psi isnt gonna live very long....


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