aaronc7

Recently had some engine damage @ the track. Still tearing the engine down to see exactly what happened and what needs fixed, but the leading theory right now is bad knock which led to other bad things happening.

I have had zero issues with the engine, tune, knock etc. running on the track before. Over the winter/spring the only thing I did was- new valvesprings (single beehive to BTR duals), new NGK TR6 spark plugs (had TR55 before) and got a retune on the dyno.

Overall mods I have a 2003 Z06 w/ mild 226/230 .604/.604 113 EPS cam, AI ported 243 heads (stock valves), headers/xpipe.

Anyone see any red flags in the tune? I see some stuff that I think may be suspect, but I want to hear the real experts' thoughts. I have also included a stock tune file in the zip file for easy comparison/see what has been changed vs going thru table by table. They are EFIlive tune files.

Thanks guys.

CTD

I'm not EFIlive so I cannot look, I'm curious as to the motor failure though. I'm not an expert, I do have a wall of shame none the less Unlucky #7 by chance?

aaronc7

Yep number 7. I did a leakdown test at 75 psi-- cylinder 7 was 14psi. Leaking into crankcase and cooling system. Tapping noise at idle too that seems to be coming from the top end of the engine. Went away if you revved past 1500 rpm. I can speculate all I want right now, but won't know for sure until I get the heads pulled off.

CTD

I had the same unlucky #7 as many have. The piston is on my wall of shame, I still remember hearing the pop on the dyno I was attending a tuning class & the instructor was running a Vette on the dyno & the same pop happened. He & I strangely were the only two that heard the pop, it was still running with no misfire so off the dyno it went.

Lots of re search on my part as to why, many theories as to why. I simply pushed my LS1 a little to much & fault only myself.

What I did learn is Kurt Urban is probably the most knowledgeable on the issue, he was involved with Motorola cars having the same problem. If I remember correctly they actually put EGT & O2 sensor's in each cylinder & could not recreate the problem. Their was a change in the fuel that had to use & the problem went away.

You may still find his posts over on LS1 Tech regarding this, he frequents Yellow Bullet. I always make sure to read his posts when he does & pay attention to what he says He does have a steam vapor kit that would probably be a good idea as you track.

Back to your tune question, if it was running the ragged edge that certainly doesn't help with a non forged bottom end. Slightly less timing & extra fuel for the track, did you ever data log any laps?

aaronc7

I have a lap timer app going always that pulls in engine OBD data, but generally I only record speed, RPM, throttle position through that. OBD over bluetooth isn't super fast, so I have to limit the number things to log so I can get a decent rate. I have done a few full EFILive datalogs during session (24 channels @ 10 hz), and everything looked great. I have a real wideband wired up as well that logs with it. Everything looked great so many I got a little complacent. It was ~20 degrees warmer than normal at the last event, but coolant was around 205, oil 255, so I was not too concerned at the time.

I have video and datalog (rpm, speed, throttle only) of the whole session where something went wrong. I did not hear anything in the video or at the time...but that could have been covered up by wind noise @ 145 mph with windows down I'm sure. I only noticed when I started up the car next time and hear the tapping at idle. I pit out a few times in the session-- if you listen closely you can hear that the second time I pit out the idle tapping is there, then I basically just go out and do a cool down lap, come back and park.

I told the tuner I would be using the car on track and did not want to be on the ragged edge, but I have a feeling he just did his normal procedure and didn't give it second thought. I do have a full EFIlive Flashscan now, so my plan for next time around is to probably have a street and track tune. On track I really have never thought "man I wish I had more power right now"... I'll take reliability and peace of mind over 10 extra HP or whatever. Another option would be to run a little higher octane stuff they have at the track, I guess.

CTD

Did you compare the IAT vs timing tables? That's a common table tuners change.

An aggressive street tune on a track could be a worry for sure. A window of error with a fatter AFR & reduce timing for sustained WOT & heat soak would be nice. As you mentioned increasing the octane for track days would have the same effect.

Sounds like your motor will have a serious wound, the fuse in #7 cannot protect it for very long. Hearing it pop on a dyno is one thing, if it happen's while you are on the track.....ugh.

If you are interested I can find a photo of #7 fuse or I can head to the trophy shelf....their are several items sitting to remind me.

aaronc7

If I remember correctly I saw around 12.5 AFR on the wideband. The IAT vs timing table is tweaked some....I don't have logs from the actual session with regards to IAT, but on the course, I never get below 50 mph so I can't imagine IATs are that crazy high or anything.

I'm more worried about ECT vs timing or something that numbs the knock response or something like that.

romandian

i think thats pretty lean.

what so special about the modified file i cant open it? (i can open the original one.)

aaronc7

In the software it says the tunes can be "viewed by anyone". I cleared all security restrictions and saved them again.... shouldn't be locked down at all.

romandian

maybe i need to update my software.

aaronc7

Finally got the car to a shop, they will be borescoping it today, then pulling the heads off/further inspection soon.

I did plug in the FlashScan to the car and saw that GM.ASPARK is at 100%. My idea was this would show me a 'historical knock' record of sorts. It's my understanding that 100% is high octane table exclusively, which would indicate I was not knocking on the track significantly over the session or anything... correct?

aaronc7

Not surprisingly, cyl 7 piston cracked in the typical spot. I had water getting into oil, but head gasket looked OK....so almost certainly there is a crack in the block. Engine being pulled today.