rabjohns

Interesting. What do you use instead?

Geoffrey

Smart Racing products has been producing a race quality bearing in several intermediate sizes so you can build the engine with your own desired rod bearing clearance. The differences are in "tenths of a thousandths"

rabjohns

Thanks

Tom W

FWIW: A few years ago, my engine was built with the Porsche rod bearings and was pulled apart after about 10 hours due to premature rod bearing failure on another engine built with the same bearings. Mine were excessively worn and were replaced with the new Smart Racing bearings. The engine was removed and refreshed at just over 100 hours this winter. Everything was in good shape despite two 'excursions' up to just over 8000 rpm due to missed shifts (it was the shifter, not the driver). The engine was built to go to 8k rpm and it did what it was supposed to without a problem. My engine obviously uses stronger springs and has stronger rods, rod bolts, etc to allow it to rev that high.

rabjohns

OK Continuing saga. I finally got the autopsy on the engine. Apparently detonation caused the rings to disintegrate and not only spread their little metal pieces in cylynder one but all over the engine. Here are some sad shots of:
- A good cylynder
- A bad cylynder
- Flecks of ring in the oil
- Etc

http://www.flickr.com/photos/rabjohn...13215907/show/

The mechanics had to split the case to clean out all the crap. There is scarring on the crank and heads. Basically I need a full engine re-build.


My Mechanic says he thinks that bad gas was the cause ( I was running pump gas - which apparently is bad).

This could have been exaserbated by one of the the previous owners running a chip (although the stock chip has now been returned). Apparently this may have disabled the knock sensor and caused the damage to continue.

So, for the experts. Does this sound right. Can "bad gas" really blow up an engine like that? Is there anything I should have done differently along the way?

Cheers

David

crg53

Sorry to hear about your trouble, but looking at those pistons, detonation would be my last thought, to me it looks more like a broken ring gone bad; mind you the result is the same, expensive repair.

rabjohns

Interesting. Do they just fail? The engine was completely rebuilt in 2004.

Streetfighter

Who is doing the work for you?

rabjohns

Midwest Eurosport the local (Chicago) Porsche racing experts.

J richard

+1 that does not look like a detonation failure, I would expect to see some melting or scorching of the piston crown at the top edge, was this a re-ring with a used set of P&C? my first suspect would be insufficient piston ring end gap, which if you run hot the ring will expand excessively and bind in the bore, and it gouges the cylinder, breaks off the ring land and then proceeds to chew itself into little bits...which happens to look alot like your pics... On a side note, I've run these motors hard on pump gas and never had an issue, the dme pushes the timing back to the point where you will really notice a drop off in power, but if run long and hot enough maybe...but I think there was an underlying issue...

rabjohns

[QUOTE=J richard;6658686]was this a re-ring with a used set of P&C?

No the previous rebuild was a complete engine case down $18k rebuild by Fairfield (edited). New pistons/cylynders and the whole enchilada.

the dme pushes the timing back to the point where you will really notice a drop off in power,

We suspect that the car was chipped before it got to me and somehow the knock sensor was disabled.

rabjohns

One more question If I am going to take the engine apart should I change/upgrade the cam? The car is only used for PCA clubracing.

Chulo

As a fellow racer in G, I'm now subscribed to watch this rebuild.

Kidding.. Eurosport does great work. My engine was just there getting a top end rebuild. Similar issue, but my rings did not explode like yours, they just cracked. Car was way down on power at Putnam last year, and started barfing up oil. Brian thought mine was bad detonation, too. My car has a stock chip. We should compare notes.

rabjohns

[QUOTE=Chulo;6660714] As a fellow racer in G, I'm now subscribed to watch this rebuild.

Ahhh not allowed. Got it

I will keep posting as things progress. I welcome any thoughts.

David

Streetfighter

I might be over there on Friday of this week. I will keep an eye out for your car. I agree they do excellent work, I just go to them for parts. They hate me!