vaross

I have lq9on my Camaro ss this is the 3rd time #7 piston break.why? I hove no nitros just head. Cam rods and froged piston and still nbroke.

SpiderX1016

We need more info than that.

vaross

Also tuned by MTI. What else u need to know?

BlackScreaminMachine

iTrader: (17)

Its due to the temp of the coolant that pass over in that area. It tends to make it the weakest piston. And your tune is too much on the ragged edge.

SOMbitch

iTrader: (8)

Because due to the intake design that cylinder on the back tends to run leanest. I have seen people on here have their injectors flowed and run the richest one on #7 for this very reason.....

BlackScreaminMachine

iTrader: (17)

Miss Information.

There have been test where the intake was turned around and it made no difference on #2 cyl where #2 starting having issues.

The injector theroy is wrong also as fuel enters the rail on the Driver side which is 1,3,5,7 Cyl. and if anything #8 would be the farthest from the source and that injectors are not designated for location, they have 100,000+ Injectors and they are put on the same for every car, randomly. It maybe more coincidence then anything else that # was the leanest.

IF that were the car, it be a PCM/Tune issue from the factory which does not happen and even with aftermarket tuning, people have not fixed it as # failure still occurs. long story short, its not a intake, tune, injector, rail issue. It's a cooling issue that shortens the safe window for most cars and factory PCMs do not have the ability to tune per cyl like a Big Stuff 3 system.

SOMbitch

iTrader: (8)

I kinda don't follow your post.....

I never said that injectors were made for a designated location. I said some guys ran their richest injector there because of this problem.

If it is a cooling problem then why does it happen just as frquently on LS1 cars with the coolant crossover (better) as the LS6 cars without it?

If this was really a problem why did GM eliminate the coolant crossover when the could have easily kept it?

Is it just me or does it seem it #7 goes more frequently on a a FAST IM? (which I have BTW)

Assuming you are right please inform me why #7 has cooling issues???

Gotta go but I will check this thread later.....

BlackScreaminMachine

iTrader: (17)

It has to do with the FLOW of coolant and the path it takes in relation to the temp. the coolant is at when it reaches the rear of the driver side head. Cars that are stock never see the issue, its when you start making power, lots of timing, and iffy tunes and they are being pushed and hammered on a regular basis. The heat over the long run weakens the piston and one day it pops.

The cross over pipe from front to back was eliminated to make room for the larger LS6 intake but the side the side lines do very little anyways.

When a good piston is put there, there is very little chance of failure. As for your earlier post, I must have mis read it. But to add to it some people toss in a step colder plug and a heavier injector.

Long story short is coolant is cooled once it hits the radiator and the heat is extracted out and when it re enters the motor, it has a path, and for some reason the back of the cyl does not get as cool of coolant as #1 or #2.

Think of it like a central air/heat system. The heat comes from a centralized source (basement). I owned a house where it was 2 floors high and the furthest point was the master bed room which tend to be the coldest where as the guest room that was the 1st stop was always the hottest and we had to leave the vent shut. In that case, over distance, the hot air cools and one room suffered more then the other.

SOMbitch

iTrader: (8)

^^^^What you are saying makes sense but..... I am not sure I 100% buy it but you have me thinking.....

I have seen a couple cracked ringlands on #7 that looked like it was due to detonation from a lean condition. Maybe the detonation was from heat and not a lean condition......? Hmmmmm....


Is it just me or does it seem like it happens more with guys running a FAST???

Pearce

That does make a lot of sense. Even though the end result is the same, the cause could be different. Too much heat plus not a high enough octane (to resist detonation) and the "hottest" cylinder would have more issues. And if it is happening more with guys running a fast IM that could be that those people tend to have more mods and push the engine harder. Like it was said earlier its the modded and engines that are pushed harder that tend to have the piston problems...its all seeming to come together and make sense. So how would we improve the cooling... more cores in the radiator, or a high flow water pump or digging in deep and improving the flow through through the water jackets?