Oil holes in case and crank

neilca · 05-16-2006, 04:56 AM

I have searched the archives but failed to come up with a like question. I have seen posts to improve the oiling by grooving bearings and cases. I have seen some on cross drilling the crank. What about opening the diameter of the holes in both the case and the crank? Compared to a type 4 engine the 911 oil holes are dinky.

Also, I am using an early 66mm non counterweighted crank. Are the two plugs in the flywheel flange plugs for oil gallies? I would like to use these holes for dowel pins.

Thanks,
neil

Eagledriver · 05-16-2006, 07:26 AM

Neil,

I suspect the holes are big enough to flow the required oil. The holes in the case on the mains are just feeding one bearing except on number 1 and number 8. I think those holes are bigger so they can flow to the rod bearings. Do you have reason to suspect that there is insufficient oil flow to any of the bearings? If you were to drill the holes bigger in the crank at the number 1 and number 8 bearings wouldn't you have to drill all the passageways in the crank to match the new size?

I'm sorry but I don't know about the plugs in the flywheel flange.

-Andy

neilca · 05-16-2006, 08:49 AM

I suspect that the oil flow is inadequate when reving over 8000 rpm due to the many "fixes" available. This is for racing applications. Street use the holes are probably fine based on the number of miles most people get from these motors.

lindemans · 05-16-2006, 12:49 PM

They're not stupid in Zuffenhausen....
Smaller holes = higher oil-pressure; besides that, which other engine has 8 crankshaft bearings....

Eagledriver · 05-16-2006, 02:15 PM

It would be interesting to see if any of the "fixes" are used by the factory in the newer GT-3 engine that revs so high. Or any of the early engines that reved high in racing form for that matter.

-Andy