M758-

That is interesting. I have not heard that explanation before. Do you have any ideas about how to combat this?

Max

 

The car I bought has a cross drilled and "knife-edged" crank, and a baffled oil pan. The seller had gone through 2 engines that spun bearings, and he told me those things were designed to prevent a repeat. I don't know what knife edged means exactly but he seemed like he really knew what he was doing.

 

search for knife edge crank and you'll find what it is. I know huntly really believed in cross-drilling.
M758: the reason I've always heard for cross-drilling or prep-drilling was that the hole was simply working against the centripital forces of the crank. The rotational forces were working against the flow of oil, and therefore overcame the force of the oil pump and stopped the flow of oil into the area of the bearings. Any comments on this note?

 

Didn't Huntly go for prep-drilling?

 

I believe so - the only difference is drilling the hole 90 degrees off rather than 180

 

Yeah, i remember Danno posted more detailed information, along with pictures, showing the differences and advantages/disadvantages in both in an earlier post

 

Well,
The first thing is to keep the oil level up. Don't overfill as this can increase foaming, but don't let it go low. Baffled oil pans help keep the oil at the pickup.

Fresh main and rod bearings require less oil. Oil Coolers keep temps down. Also oil like Mobil 1 had a noticeable drop off in oil pressure when hot underacing conditions. I run Amsoil racing and it stays 4bar plus. I have heard redline is good too, but have no experienece.

 

Do you have any idea why our cars are more susceptible to this lack of flow than other cars? Could the oil pump be upgraded?

Max

 

I believe the flow rate is marginal. What that means is that potential volume of oil supplied is enough to support the bearings, but does not provide enough extra for hard duty. Reason for this? It is in the Porsche design. Rememeber that the 928 has similar problems. I am not sure what about the design that does it, but some thing is not quite right and either is not an easy or is an expensive fix. If it were easy I'd be Porsche would have done it years ago. Then again maybe it is just that these were not intented to be "racing" motors.

 

M758, if our motors are not "racing" motors than what did the factory do to all the cup cars and the few LeMans racers that used engines from this family? Maybe they just swapped rod bearings every race or two. That might work. Rod bearings themselves aren't too expensive. The labor is the tough part.

Max