Stan.Shaw@Excell.Net

I wasn't aware of the issue that the main bearing would be robbed of oil. Interesting.

drnick

IIRC most all the 2/6 bearing failures have either occured on track or the autobahn with high revs and high Gforce turns - these both combine to lead to oil starvation, as oil moves up the side and into the rear of the pan getting whipped into foam by the spinning crank thus providng aerated oil to the pickup. the other factors include potential pooling in the heads and a low oil condition from excessive prior oil lifting getting sucked out through the intake. this is my take on things and if correct i would think that a drilled crank is not essential as long as rpm is maintained within factory specs. the main problem is both aerated oil and not enough quantity of oil. the 928 pan is too small and dosent hold enough oil.

Vilhuer

All it should take is to keep revs below certain rpm and enough oil for the pump. Crank scraper should take care of the second, electric, mechanic or mental limiter fixes first one.

Skunk Workz

Dismantled our 944 engine,which has seen high revs (track/fast road use) and the rod bearing on # 2 was worn far more than the rest,which is "normal"...looking closely at the main bearings the #2 main bearing is also alot more worn than the rest. If the crank alone was the problem,and crossdrilling solved it,this would not happen...

drnick

ok so which is better, a crank scraper or a drysump? i like the idea of the drysump because it is also creating a vacume and storing more oil than the standard system.

heinrich

I believe a drysump cannot logically fail. However Mark Anderson did indeed have a 2/6 failure with a drysump which never recurred after he added cross-drilling. 911's have been drysumped forever and they do not have oil issues. But then they are not a V8. I have to believe if you keep feeding the monster oil, it will not somehow starve.

heinrich

Nick a scraper is like a tissue. A drysump is like heart bypass. Question is not sump vs scraper - it's sump vs drill.

John Veninger

The correct fix is redrilling like a Chevy crank. The 928 is already "cross" drilled. Just adding holes to the rod journal does nothing, just ask Stan!

You feed each rod from the adjacent main bearing, including the main #3. This is how my 928 drilled crank works and also my stroker crank.

heinrich

I stand corrected oh PCA rep ... Chevy-drilled. Mark Anderson Chevy-drilled his crank.

H2

So am I hearing that, to date, the 2/6 bearing issue has not been unequivocably resolved? And may not be until we have more test cases to compare against? But that there's pretty good evidence that x, y, and/or z may, probably, mostly likely, usually make the fix? But that the jury is still hanging on this? Since the number of mods to resolve the problem have been relatively small but does seem to point to a solution, there's not really full consensus on this issue yet...it seems from what I'm hearing. It's enough to drive an **** retentive person crazy.

Harvey

heinrich

Harv Mark Anderson has "chevy"<JohnV> cross-drilled crank and drysump which is beautiful (I looked) and NO PROBS.

John Veninger

My guess is that a drilled crank and accusump has "cured" the problem on the track, so the fix is pretty cheap if you've blown a motor. You add the one time $1,500.00 insurance policy during the rebuild.

For the street, as long as you don't over rev the car and keep the oil topped off everything is fine. Some have added an accusump to the street car, makes a nice pre-lube before you start the engine.

evil 944t

For a track car, I would rather the dry sump. Its the same price as doing all that was listed and you will even pick up a little HP. No?

John Veninger

Not the same price. Accusump will run you ~$600.00 for all the parts and bolt on in an afternoon. Dry sump parts and installation will be much more complicated and expensive.

heinrich

Accusump ... 600 bucks .... starts to sound interesting ....