sstv

This motor always had piston-slap at idle. The #7 Cylinder appears like pre-detonation? ...to me. Why? ...the heavy carbon/oil residue on lower side of other cylinders?

Anyone with extensive engine failure knowledge? ...care to take an educated guess? If it's a fuel delivery problem? ...I would hate to have a re-inactment of this senario with the next longblock. Lubricant was 5-30W Mobile 1, changed consistantly.

Thanks.

hellbents10

iTrader: (10)

What mods. Bad tune? not enough fuel and too much iming.

NataSS Inc

iTrader: (9)

Kind of hard to tell. Shadows and lighting can hide or make certain things stand out to much. To me #7 looked like it had a trainload of detonation going on w/ the way the top of the piston is pock marked. the others look like they have ALOT of carbon buildup and oil in them. Maybe the PCV wasnt working well and blow more than normal amounts of oil into the intake track. This might explain the detonation, to much oil will lower the octane value in the fuel causing the detonation.

those are just my thoughts. I am FAR from an authority on this.

Dope

iTrader: (2)

Just FYI, #7 is pretty much always the leanest cylinder.

Maybe my monitor sucks, but what burn pattern are you talking about? All I see is the shape of the piston, with the 'heart' shape of where the clearance for the valves would be.

Could have busted that injector and leaned the crap out of that cylinder.

It's pretty normal to see carbon buildup on the pistons from oil, with the stock PCV setup.

What mods? Nitrous? What were the symptoms leading up to this? I imagine there must have been a lot of detonation.

Dope

sstv

Engine is Stock, No-Mods, Daily Driver. Oil usage varied between 1-2 qts. every 2 weeks.

longdaddy

OUCH that's a lot of oil!

Thunder175

I just find it hard to believe that a stock engine with no mods would do that. To me it looks like those cylinders leaned out way to much and burned those pistons, same as what the other guys think. I've seen that kind of damage with extreme nitrous setups where guys would literally burn holes right through pistons.

I just don't see how an un-modified engine could do that unless something somewhere let go. How as the car running before you tore apart the engine?

Bowtieman4life

iTrader: (1)

At first glance I thought you were running a dry nitrous kit and that cylinder got way to much nitrous and not enough gas but after seeing your post, I think it was a bad injector. The other cylinders look like they were burning oil for a long time.

goober35

iTrader: (1)

The burn marks look like they are from the vavles in a way. Where the burn starts on the bottom of the pistons is where the least amount of air hits. Sens when the vavle opens the air hits the top of the piston the most.(does this make sence).

Damn man i have never seen that much oil on the surface of the pistons and on the surface of the block. Look like you just pored it there.

Ryan K

iTrader: (11)

The marks you have labled are the normal burn pattern for these engines. It should make sence, the quench is very tight at that part of the piston. All of the air/fuel is in the chanber near TDC and as the piston starts its travel down the flame front moves out to the top of the piston from the bottom.

Your Oil consumption was definatly too high, I would atribute your failure to detonation from oil contamination. How does the bearing look?

Ryan K.

Thunder175

It isn't normal to burn the piston bad enough to expose the first ring...

Ryan K

iTrader: (11)

The piston is not burned to expose the first ring, ITS BROKEN.

Noyzee

iTrader: (37)

Its normal to brake a pistion yes, but on a stock block. not so comon placed imo.
My stock turbo motor with almost 50k 15 being with well over 500 rwhp looked better then that. I did have the eye brows from the valves to.
That sucks.