The pistons (JDM p73) were in a gsr with a gsr head. So compression was around 11.3- 11.4. Never heard any knocking or pinging at high rpms only if I took off in to low of rpms (bogged it). All the ringlands broked on the exhaust side. Same area and about the crack points. Do you think it was the machine shop pressing in the pins and stressed the piston? I only ask that because the machine shop ruin an earlier set of ctr pistons by gouging the ring lands up. And the only reason I let them press the pins on the new set is that they would do it for free. Guess free wasn't worth it.

 

Full setup?? Was it tuned at all, any ideas what the air fuel ratio was? What gas were you running... premium? Lots of threads like this in boost land, my friend junk his ringlands twice with a jackson racing supercharger, and the fmu. No problems with his turbo, and my tune though. Hard to say if the shop was at fault if you aren't sure the rest was all good.

 

Looks like detonation, too much timing at low rev's.

 

I'm with DonF on the detonation, but I'm wondering did you overheat?

 

What about over-reving? would that cause it?

 

detonation

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by h2b_eg8 &raquo;</TD></TR><TR><TD CLASS="quote">detonation </TD></TR></TABLE>

 

Timing was stock on a stock ecu (p72). The car didnt overheat. All of a sudden it began to run like crap and a compression check reveal no compression in one cylinder. Thanks to everyone that answered.

 

detonation...


just cause u cant hear it , it doesnt mean it doesnt pre ignite or detonate...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by acid-burn &raquo;</TD></TR><TR><TD CLASS="quote">detonation...


just cause u cant hear it , it doesnt mean it doesnt pre ignite or detonate...</TD></TR></TABLE>



It has always annoyed me when people are having problems with their setup, and someone suggests detonation and they reply "its not detonanting". You then ask how theyre sure of this, and they reply "cuz we cant hear anything".

I would put the plugs under a decent magnifying glass and look for the tell tale signs.

 

ive read that even the worst case of preignition is silent anyways. the pressure rise/crank degree is drastically different than detonation.

you dont press pins in,, you take a bottle torch, hold the rod in your hand, heat the little end evenly through yellow and into faint blue/purple, then hold them between the bosses and slip your already lubed/set up pin through. stop going to that shop.

check the chamber for lots of loose carbon, overheated spots, random shiny spot among carbon buildup.. large missing flake, etc. was it only one cylinder?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by civic2slo &raquo;</TD></TR><TR><TD CLASS="quote"> Never heard any knocking or pinging at high rpms only if I took off in to low of rpms (bogged it).</TD></TR></TABLE>

the higher the rpm, the less time the cylinder is at a small volume/high cylinder pressure.. the volume grows rapidly and pressure declines rapidly, preventing detonation.

bogging means that the cylinder pressure wasnt even able to turn the crankshaft, and the chamber volume stayed small (near tdc) for a semi-eternity while a flame propogated across the entire chamber, creating massive pressure rise. the pressure wants to force the rings down, the crank/rod/wristpin/piston are almost stalled and want to remain upright. the ringlands have two pressures on them, upward on their inner circumference, downward on the outer circumference. they compromise and go both ways. thats what you got.

the bogging was your problem.

 

I wasnt driving the car though I was a passenger in it many times. Oh well live and learn. my other friend has the same setup with no issues for over 2 years before he sold his car. So thats why I thought it may be a machine shop issue. Yes the piston look like alot of the aluminum melted away. My first thought was a faulty injector.

 

CC ,


yup! ive had and saw a bunch of motors run well or "ok" with no audible signs of pre ign and what not..

when removing the head though.. i can see signs of knock or pre ign.

hard to explain.. but im pretty sure u know what i mean and how it looks like hehe

, seen ringlands broke /crack /fall off with the tops of the pistons lookin normal too..

to the OP , not one engine is the same.. even if ur friends set-up was 110% the same as urs, tuning them , i can bet u that the maps are gona be totally diff...
kinda hard too if u didnt drive it,

but its all gud, learning from those things is always a good thing... making the same mistakes

good luck...

 

dyno ? a/f read outs ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mike_belben@yahoo.com &raquo;</TD></TR><TR><TD CLASS="quote">

the higher the rpm, the less time the cylinder is at a small volume/high cylinder pressure.. the volume grows rapidly and pressure declines rapidly, preventing detonation.

bogging means that the cylinder pressure wasnt even able to turn the crankshaft, and the chamber volume stayed small (near tdc) for a semi-eternity while a flame propogated across the entire chamber, creating massive pressure rise. the pressure wants to force the rings down, the crank/rod/wristpin/piston are almost stalled and want to remain upright. the ringlands have two pressures on them, upward on their inner circumference, downward on the outer circumference. they compromise and go both ways. thats what you got.

the bogging was your problem. </TD></TR></TABLE>

Nice explanation. Realizing there are many variables here, in general how can one determine the lowest safe WOT rpm where this situation would not occur?

 

probably at the lowest rpm that mashing it produces wheelspin, which will be different for every gear.