[AaronDC]

The new racecar went to it's first race last weekend. It's an endurance car, so we typically race 16 hours for a single race. We made it about 6 hours in, and popped a motor. We spent Saturday evening swapping motors, and ran about 4 hours Sunday. Now we're trying to figure out why the first motor went.

Initially, the car started making some metallic rattling noise. It didn't sound deep enough to be bottom end related. And the noise would go away with the right about of throttle and rpms. We pulled valve covers to make sure something wasn't loose in the valvetrain. All that looked good. If it was in the bottom end, and making that noise, it was too late anyways. So, we put the valve covers back on, and sent the car back out. It made it half a lap, and popped.

I know some of the guys on this forum have a lot of experience with motors in general. Can anyone see much from the pictures below? We were having lots of fuel starving issues due to a terrible fuel pickup in the fuel cell. The tune was also not dialed in at all. Thought we had played the tune conservative by fatting up the fuel, stock timing, and lower rev limit.


Link to Photobucket album:
http://s184.photobucket.com/user/AaronD ... /Lightning

[EDS50]

We were having lots of fuel starving issues due to a terrible fuel pickup in the fuel cell. The tune was also not dialed in at all. Thought we had played the tune conservative by fatting up the fuel, stock timing, and lower rev limit.


Link to Photobucket album:
http://s184.photobucket.com/user/AaronD ... /Lightning

I think the fuel starvation you mentioned pretty much sums it up.

[decipha]

Lean blows engines

[cgrey8]

Did lean cause that or detonation? Or was it just stock components that got pushed beyond their limits?

[LeadHead]

Guessing this is a LeMons car?

Metallic rattling that goes away at certain throttle/RPM conditions is almost always detonation. It can be caused from running too lean and too much ignition timing.

It looks like the center piston there is what broke first. Either from detonation pounding it, or perhaps the piston pin was a little loose and it just hammered the piston apart.

[teal95]

Nice to see another nutcase here. We're running a 1987 Mustang that was an ITB car in SCCA in a previous life. It now has a 2.3t in it. We've did 3 races with it last year (NJMP, Summit Point and VIR 24). We go to Monticello next weekend.

steve

[Jetfast50]

That motor was to rich,over timed, with to hot of a spark plug, and the fuel was not cold enough.