gapp94vert

iTrader: (15)

Hey guys I need some help trying to figure out why this happened to that cylinder. I was racing the car at cecil county saturday when it happened and didnt notice a noise till the motor was cool and I started it up to leave. I also just had the car tuned a couple weeks before and and it was tuned a little rich it actually picked up 15 horse when it was richened up. The motor only has about 60,000 on it with ported ls6 heads and a cartek 2x cam.

Ive swapped intakes a couple times over the years and I always noticed that the #7 runner spray pattern always looked a little different like it was not getting enough fuel. Also when I pulled the intake off this time that runner was almost bone dry. I took the intake off a couple months ago to paint it and noticed it again and I also didnt put the injectors back in the same order so im not sure if its the injector. In the pics you can see what im talking about.

I mainly want to know because im thinking the injector failed at the top end of the track and im probably going to buy a shortblock and dont want this to happen to the new motor. I also couldnt hear if the car was pinging at the top end with the helmet on and the car floored.

http://www.flickr.com/photos/58569970@N02/5813057549/http://www.flickr.com/photos/58569970@N02/5813057549/ by http://www.flickr.com/people/58569970@N02/, on Flickr

http://www.flickr.com/photos/58569970@N02/5813626142/http://www.flickr.com/photos/58569970@N02/5813626142/ by http://www.flickr.com/people/58569970@N02/, on Flickr

http://www.flickr.com/photos/58569970@N02/5813056597/http://www.flickr.com/photos/58569970@N02/5813056597/ by http://www.flickr.com/people/58569970@N02/, on Flickr

Chevy Guy

iTrader: (2)

Its not your fault or any defective injector.

#7 on the LS engine is a known bad cylinder. Apparently there are oiling, heat dissipation, and lean mixture issues around that cylinder. Cyl 7 piston failure is very common. Search the Corvette forum for loads of threads and details.

Fastdriver1992

iTrader: (1)

same thing happened to my #2 cylinder

gapp94vert

iTrader: (15)

Thanks I did research and came across alot of threads I was just wondering because I thought it was odd that the runner was dry when all the rest were oily

Rubrburnr

iTrader: (1)

Yep, mine went out as well. I was noticing more and more smoke coming out of the exhaust. It was getting so bad that I didn't like the smoke screen it was producing. Alas the picture speak for itself...

fastassls1maro

iTrader: (22)

my #7 let loose as well at around 100k miles. Just started smoking pretty bad on decel and startups. Rebuild time!

softballnrd27

iTrader: (4)

Does this happen to all LS based motors? I have a 2004 6.0l Iron block.

O2Form

One thing caused that, TOO LEAN and maybe too much timing. Number 7 runs very hot and lean because the air rushing into the intake wants to collect at the rear of the intake. Funny you don't see this damage using the stock GM tune because GM made sure it stays cool enough not to overheat the rear pistons.

IMO your tune was the problem, I would seriously consider finding a safer tune. I'd like to see the spark plugs close up, are the porcelin centers melted or damaged?

joecar

If you picked up 15 HP by richening it, then you were dangerously lean, the damage probably was already done...

Number 7 intake port being so clean, piston being relatively clean, these support that there was poor compression/combustion for some time.

gapp94vert

iTrader: (15)

I did take a close look at all the plugs especially number 7. I put new plugs in before driving to ocmd which was about 400 miles round trip then drove another 120 miles to cecil county a couple weeks later and drove it another 120 miles home. I can get pics but when I pulled the plugs they actually looked new the porcelin was still white but the tip had some carbon on it. I expected them to be a little brown so maybe it was a little lean. I also just had it tuned and I know they made it a little rich because it actually picked up 15 horse when they richened it up. Thanks, Joe

gapp94vert

iTrader: (15)

I was writing my other post and didnt see yours till I posted my last reply lol. That does make sense half the time I race its usually in july and august. I usually run events like super chevy and nmca where its always hot as hell around the 90s so im sure that didn't help. Thanks, Joe

O2Form

Who around the Palmerton area tuned it?

94mustang

iTrader: (1)

learn something new everyday...