VetteVinnie

Just had a friend lose his LS7 to a cracked piston that ended up putting a hole in the block. It's a 2008 with an LPE 630 package. Shop told him that the #7 runs lean on these. Fact or fiction?

Stock valves, BTW, and no sign of valve failure. My guess is detonation.

BSSN

Has the longest intake runner probably.

Fartpipe

Did he have a factory ported intake or fast 102?

lane_change

What would that matter out of curiosity?

VetteVinnie

Factory intake.

Dirty Howie

PureSwank

I'm guessing his using their 3 year warranty to fix the problem right?

Elaborate please.

Bill Dearborn

Since the engine is port injected that shouldn't make a difference. No fuel in the air stream to drop out of mixture along the way. If anything it should run rich if there is trouble getting air to the cylinder.

Bill

VetteVinnie

Rich? Interesting. Someone else thinks it's lean:

The work was not performed by LPE. They just provided parts for the package. Work was done by an authorized installer, so I'm not sure what warranty would cover the motor itself. There'd have to be evidence that the LPE components or the tune were responsible, I'd think. Don't know what warranty coverage if any he'll get. I'm more interested in understanding what could contribute.

tjwong

It is possible, the PCM does control fueling to both banks individually. But it can't (not during normal closed or open loop operation) trim fuel to individual cylinders. If the o2 sensors sees rich or lean conditions for say the left bank, it will trim the fueling as it sees it. So each cylinder on that bank gets less or more fuel based on the o2 sensor in that bank. So if say number seven has a air flow imbalance, and if the o2 reports a rich condition, and the PCM reduces fueling to that bank, it is possible that it can be a bit lean. However this would only be during closed loop operation, in PE fueling during > than X throttle position, the PCM fuels based on a PE mulitplier. A stock Z with stock engine calibration is inherently rich. If a "tuner" reduces PE fueling there again number 7 "could" go lean if conditions are right. I personally have not seen any issues in my shop. Detonation is more than likely the culprit that caused the problem, that is where I would put my money.

0Randy@DRM

Fact......

Randy

obzidian

Bill:

This is a problem that has been apparent since the ls1 intake was introduced and those are also port injected. If you wish, jump on tech and search for cylinder 7 lean threads.

Nothing new and something tuners have been dealing with for years now.

Also, if you search some of the threads here about engine failure you will also notice a trend about which cylinders tend to go first. There is something there to look into.

bowtiguy

must have been an early 630 package as most of the heads coming out of LPE lately have had ferra solid SS exhaust valves, my father stepped up to the Inconel solid exhaust valves.

slapping those stock hollow things with .688 worth of lift would not be a good combo ..thats why I went Delwest Ti I/E.

VetteVinnie

Okay, can't guarantee stock valves. Just that there was no sign of valve failure - all intact. I don't think the owner knows whether or not the valves were replaced.

So all this talk about the Fast intake versus stock, is there something to that? Is the design improved in those that can help alleviate this problem?

obzidian

Well, detonation is something to consider however, this is definitely not the first time I've heard/read about a ls-series engine having a cylinder #7 (or a rear cylinder) failure due to a lean condition.

That is one of the reasons I went BS3 when I was initially piecing together the build for the camaro. Individual cylinder programing for fuel and spark... among other trick features.

BADZ

Was this Chris's car Vince? Was he running nitrous on it? I think somewhere I read he was running the bottle. I would go back to who tuned the car if nitrous played a roll in this failure.

Frans96ss

Its a fact number 7 runs leans. It always cracks the piston in the same spot too .

VetteVinnie

No nitrous (at least not that I know of). That's just rumor and speculation. Yes, Chris's car.

VetteVinnie

Here?

ajw2500hd

Forged pistons would be a great idea then?!?!?!