Jacked my junk Saturday night...

[Georgiarocker]

Hey all. Noobie here. Posted this info in my 2 other fav. forums, just sponging up info and conversation. Interested in what you guys have experienced and/or have to say.

History of my junk:
2004 LS1 GTO M6
Maggie, 8psi, 590(ish) lift on my blower cam, meth injection, 19 deg. advance, 100 dry shot, ~10,000 miles on my TR6 plugs and 918 springs; ~100 1/4-mile passes on the blower and at least 30 with the nitrous. Stock bottom end, stock tranny, and stock rear end.

Last few trips to the track:
Been trapping 120-124 @ 11.5-11.7 on 1.79-1.85 60's for awhile.
Shifted some weight around in March and began cutting 1.58-1.65 60's.
3/30/08: 2 passes. 11.6@118/1.62; 11.3@120/1.58
4/12/08: 3 passes. 11.6@113/1.66 (3 degrees KR in every gear); 11.5@118/1.62 kicked out cord, no data; 12.0@109/1.67 (1-1.5 KR in 3rd)

It happened on the 12.0 pass when I hit 4th gear. Sounded like cylinders were out. Running extremely rich. woof-woof-woof-sounding. Oil pressure was good. No smoke. No leaks. No catastrophic sounds.

Hobbled the car back from the track and let it sit for 2 days.

Preliminary investigation from this afternoon:

Moved car, noticed exhaust cylinders 3&5 cold.

Pulled all plugs; 3, 5, & 7 damaged (melted). 1, 2, 4, 6, & 8 looked great.

Compression check all good except #5... zero psi

Blow air into #5, heard air in exhaust pipe with rockers removed, valves closed.

Springs were good.

3, 5, & 7 were hot, suspect driver side head gasket or injectors.

bottom end is probably fine but need to swap drivers side head and check for piston damage.

[slims00ls1z28]

Sounds like ya went lean on that bank melting the plugs and possibly a hole in the piston. Never heard of melting a valve but if the plug was damaged it is possible something came off and could have contacted the valve causing it not to seat letting the air into the exhaust as you describe. Last time I saw some thing similar my valves (exhaust, all of them) smacked the pistons on an over rev, one of which eventually broke off exploding the piston. Pulled the valve covers and rocker arms off noticed right off the offending valve stuck up alot higher. Pulled that header off and sure enough I could see all the way down into the block. My cam was a little larger though (MS3). block was destroyed knocked out the cylinder liner and supporting material behind it but not out the block. Externally everything looked fine. Pull that head sounds like something major went wrong I'm betting on a lean condition as the culprit.

[0rion]

Sounds like swiss piston to me too.

[superchargedblackgto]

What kind of fuel upgrades do you have?.....it does sound like you went lean......Are you running a Wideband?........If Not I say ALL hope is lost.....LOL
sounds like a rebuild, look @ the bright side
Brad

[Georgiarocker]

What kind of fuel upgrades do you have?.....it does sound like you went lean......Are you running a Wideband?........If Not I say ALL hope is lost.....LOL
sounds like a rebuild, look @ the bright side
Brad

93 pump gas and methanol. 42# injectors running at 75% duty cycle (so says HPT) however, I plan to have them flow tested after I get this heap home this weekend.

I'm gonna try to tackle this one myself for once with some technical baby sitters standing by, (or leaning, depending on how much beer I feed them).

First thing I want to do is a thorough compression check to compare all cylinders before I pull the head and look for carnage. Looking for a how-to...

[Sleeper101]

Ya it sounds like a hole in the piston. I Doubt you hurt the valves. ONly way to find out is crack it open and hope for the best. Good luck!

Have you drained the oil to look for any chunks?

[superchargedblackgto]

93 pump gas and methanol. 42# injectors running at 75% duty cycle (so says HPT) however, I plan to have them flow tested after I get this heap home this weekend.

I'm gonna try to tackle this one myself for once with some technical baby sitters standing by, (or leaning, depending on how much beer I feed them).

First thing I want to do is a thorough compression check to compare all cylinders before I pull the head and look for carnage. Looking for a how-to...

not concerned with the duty on the 42lbers its the supporting fuel system, what pump are you running?....or duel pumps?

[Georgiarocker]

not concerned with the duty on the 42lbers its the supporting fuel system, what pump are you running?....or duel pumps?

Uh... stock fuel system.

[Georgiarocker]

#2 - 187lbs
#4 - 181lbs
#6 - 180lbs
#8 - 175lbs

Passenger side looks good, I think. So, I'm leaving that head alone.

Maggie is off, rockers & pushrods are out. Don't have a 1/2 drive 15mm, so the headbolts gotta wait till tomorrow. Then, I'll inspect for joy or carnage.

I'll keep you guys posted.

[superchargedblackgto]

Uh... stock fuel system.

there is the problem.....Id almost bet #7 piston has a hole in it.....I believe thats the 1 that runs a little lean....... don't remember could be wrong....but your stock fuel pump cant keep up with those mods....I had a boost-a-pump on myine @ 8psi and it was cranked up couldnt keep up
Brad

[Georgiarocker]

there is the problem.....Id almost bet #7 piston has a hole in it.....I believe thats the 1 that runs a little lean....... don't remember could be wrong....but your stock fuel pump cant keep up with those mods....I had a boost-a-pump on myine @ 8psi and it was cranked up couldnt keep up
Brad

You're correct that #7 runs the hottest. Another intersting factoid about #7 I learned during my initial install: it's the first one to get oil, and the o-ring between oil pump and the oil pump screen goes bad quickly and allows the oil to become slightly aireated and since #7 is the first in the oil chain, the lifter doesn't pump up completely and causes many a mechanic to misdiagnose it as a bad lifter, false knock, and much more. http://www.pistonslap.com/tsb/020601038.htm

As for whether or not my stock fuel pump is, or is not keeping up... I've had EXTENSIVE time on the dyno testing and re-testing each of my mods as they went on. My tuner/installer is a very conservative guy and errs on the side of caution in every instance. Also, I'm using a ton of methanol which lightens the load on the pump. I check my meth injection system before every track day and it was operational the day things went bad. Plus, #7 is still holding compression pretty well. But who knows, you may be right. I'll keep that in mind when I have my injectors checked. Right now, we're leaning towards less than optimum injector performance.

The head will be off before noon today, so I'll provide an update with pix.

[Georgiarocker]

Can't upload pix... guess I haven't been a member long enough or have enough post count.

You can check them out here:

#5 & #7 Pistons: link

#5 exhaust valve: link

[superchargedblackgto]

Can't upload pix... guess I haven't been a member long enough or have enough post count.

You can check them out here:

#5 & #7 Pistons: link

#5 exhaust valve: link

second link didn't work, but you can post a pic use photobucket and click on the little scenery image and put the hhtp image addy in there..
Brad

[Georgiarocker]

About 30 hi-rez photos of my day can be found here:
http://www.putfile.com/album/0/georgiarocker

[Sarge]

Eating a piston in a LS1 is a excellent excuse to go with a 408 Stroker iron block Been there/Done that.....

[Georgiarocker]

Picked up a replacement head, gonna swap my 918s in tonight.
Awaiting delivery of head bolts, TR-7 plugs, and new meth pump.
Sent injectors off to be evaluated, serviced, cleaned, and flow matched.

[Georgiarocker]

not concerned with the duty on the 42lbers its the supporting fuel system, what pump are you running?....or duel pumps?

I discussed possible fuel system issues and my tuner reminded me that my race tune is loaded with methanol, tons..., and that fuel is actually pulled out of the tune... even under boost and n2o. He's confident that I do NOT have fuel delivery issues with my stock pump. That said, I'm having my injectors and methanol pump evaluated first, then I'll go from there.

[mark21742]

I hope you get it all back together!

[Georgiarocker]

I hope you get it all back together!

Just waiting on my headbolts to arrive

[mark21742]

did you go with stock, or ARP? For the price, I'm going to go for the ARPs when I finally crack my motor open!