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 Corvette C5 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.

subeone

iTrader: (5)

what file is that

aaronc7

It's 2 x EFIlive tune files. One is what I was running and the other is a stock tune file.... same VIN so you can easily compare in the software

ss454327

iTrader: (10)

What lifters are you running? Stiff springs might have killed one.

aaronc7

"LS7" lifters. I replaced them when I had the heads off... less than 10k miles on them. I originally had PSI 1511ML springs, but the car showed power flatlining near around 5000 or 5500 rpm on the dyno and we suspected it may be valve float-- that's why I swapped to the standard BTR duals. I kept the old springs, never got around to testing them to confirm.

oreobadr

The timing is a pretty aggressive but nothing super crazy as long as you were running good fuel. I looked at the VE tables and almost hit my computer with a hammer. That thing is disgusting.

oreobadr

Also, is it just me or does his MAF frequency table lack resolution at high flow rates? It seems like the slope is pretty extreme on it. Possible lean detonation situation.

aaronc7

oreobadr, thanks for taking the time to have a look at the tunes.

Yeah, the VE table work just looks lazy to me.

I know from doing a few logs on the street that knock wasn't present there. Maybe bad gas, hard to say. I drove 240 miles out to the track, topped off with fresh fuel at the track before I ran- so it should have been pretty fresh.

What do you think about B6203-6212? Tables like Knock fast attack rate values were halved and knock limit in/out PE mode table significantly reduced.

oreobadr

what running conditions was it in when the damage happened? High rpm high MAP?

Also, I think the b6203-6212 tables are pretty crappy. Seems like the tuner did a really aggressive tune and a half *** job in my opinion. I wouldnt go back.

aaronc7

road course, 20 minute session. It was pretty hot that day, low 90s. I never really go below 50 mph once on the track, I wasn't logging IAT, but I wouldn't suspect it to be super high-- maybe only initially after sitting idling before going out on track. There are a few good straights where I am WOT 3rd to top of 4th (up to around 145 mph). I had digital display of oil temps, they hit around 255 260 max. Coolant I was looking at analog gauge, it never hit 220, I would guess 210 max-- nothing crazy.

I did not hear anything on track while I was driving nor can I in the recorded video. Something happened towards the end of the session, I did a cool down lap, came back to pits and then noticed the tapping noise at idle (no weird noises or anything abnormal above 1500 rpm).

Thanks for the feedback again. Hopefully I can narrow it down to probably tuning issue or hardware issue when I get the heads off soon. Leaning towards tune at the moment, but we'll see.

foxsl

iTrader: (1)

Maybe the VE is ugly because they have it in maf only mode as sometimes shops do that so they don't have to touch the VE. I have hp tuners so I can't open the file to check what mode it's in.

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 (think its called something else in hp tuners) 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.

ddnspider

iTrader: (26)

this is accurate.