Well, a couple weeks ago I lost a piston at the track... Managed to drive home (only 5-6 miles) on 7 cylinders, but had to have my friend bring his trailer to get the car down to his shop. (Harden Motorsports in Nashville, Indiana)

He pulled the motor yesterday and found the following:



This is a heads & cam car (see sig), never been sprayed, tuned by yours truly both on the road and on a dyno. On my last dyno run, I was running a little RICH, not lean. But the piston melted anyway.

Only thing I can figure is that on my last run at the track (on a cold night & very slippery track), the tires broke loose when I hit third gear and I didn't regain traction until I let off the gas. I bounced off the 6,900 RPM rev limiter a few times, and maybe I maxed out the stock injector on that cylinder when I did that.

Anyway, the block & heads appear to be okay, so I'm going with a .005" overbore and forged rods & pistons... And maybe a new set of 30# injectors?

 

looks familiar... #7 ????

 

Yep.

 

hmmm

 

wonder if running 1 30#'r would work

 

what springs you running 918's?

 

987's.

 

What kind of power did it make? You can PM me if you would like.

trying to get an idea of where the injector stood in terms of maxing out.

 

I only have 365rwhp unlocked but runs in sig so??

 

Hey Louis. At the wheels, with the 9-inch rear and the TC locked, I pulled 378 RWHP at 6000 RPM, dropping only to 374 RWHP by 6500 RPM.

(Oh, and just to put a face to a [screen]name, I'm the guy that hung out with you guys at IRP when the One Lap of America came to Indy. Never did get that video posted, sorry.)

 

I remember now

Any Idea where your injectors stood, even on the dyno?

Im sure that it didnt help being as cold as it was that day. ATAP or anything or the like?

 

No, unfortunately. I have AutoTap, but wasn't using it that night. (I had THOUGHT I was just running for fun that night... Wasn't even running slicks. Little did I know. ) I haven't done a full dyno-tune, just a 3-pull baseline with a wideband. (Just enough to get the A/F in the right range.)

Memo to self: Get thee to a dyno with thy laptop and LS1_Edit & AutoTap cables once thy rebuild is done.

 

What was max timing afvance and what kind of fuel/plugs/compression?

 

what type of fuel?

 

11.1 to 1 compression.
Shell 93 octane gas.
NGK TR55 plugs/Taylor ThunderVolt wires.
29 degrees timing advance at high RPM/high load.
No headers, just stock manifolds with gutted cats, through an SLP Y-pipe and an SLP dual/dual exhaust.
(Getting TR headers before the rebuild is done though. )

 

what kind of oil

 

I'd say with 29* timing and 11:1 with 93 octance it is possible to get detonation. Wouldn't really think so though. Did you ever get any KR on your atap runs with that tune?

 

Oil: 10w30, with a couple quarts of 20W50 thrown in to try & slow down a minor front oil seal leak until I could get to it.

I never had ANY knock retard on my "on the street" testing with AutoTap, except in fuel cell 12 (low RPM/high load). I got rid of most of the knock in cell 12 by throwing in extra fuel under those conditions while reducing the timing for those conditions.

 

Hey killer, but how did you know when you melted the piston. What were the syptoms? Smoke? Rough idle?

 

Lost part of the piston crown?

Heat + ring expansion can cause that, car might have been too lean?