the late cranks have a longer snout for the PS pulley so unless you are running manual steering this won't help you

 

LOL - so that's why my PS pulley will never index correctly. Kinda tough to rectify now. That is just funny - I'm so stupid sometimes it hurts!

 

It's something so minute too, I think I read it was like a 2mm difference. Oh well you live you learn and you move on.

 

My thoughts on the cross-drilled crank:

Go for it. if you're gonna be in there anyway, get it done. safe assurance that you're less likely to spin a bearing. that's what I did. but my mistake: I went with Huntley Racing...

 

"Hmm, is the original hole welded closed or something when it is perp/cross drilled? Otherwise you will always increase the area of the holes..."

The extra hole actually doesn't increase flow or reduce oil-pressure. That's because the flow-limiting part is the bearing-clearance. It doesn't change with one hole or two, so oil-flow and pressure remains the same as before with one hole... except at high-RPM:



The perp-drill hole on the outermost part of the rod-journal uses centripedal force from the spinning-crank to force the oil out of the journal and increase its pressure and flow at high-RPMs. Every single high-RPM I've ever seen from 8000rpm Supras to 14,000rpm motorcycle engines have the journal hole on the outside edge. Not sure why Porsche did it they way they did, perhaps so they can drill all the holes in one pass on the crank or something. Anyway, the 928 guys have seemed to confirm that the perp-drilling fixes spun bearings on those engines as well.

Brendan, the shops that does my work are actually more engineering firms than auto machine-shops. I send them a CAD file and they feed it to their machines.

 

Well it looks like perp-drilling the crank does prevent the rod bearing spining and from Danno's picture it would seem cross drilling doesn't help as much but the big question is does it solve the problem? Anyone who really dogs their car have cross drilling and ever sping a rod bearing still?

 

So you only have a cad file for the 944 crank? Did you make the Cad file yourself?

There is no reason to do this for 750 bucks if you know of ways (and others) to get it done for a couple hundred (with same attention to quality, etc)

 

I've yet to spin a bearing with my cross drilled crank. I race all the time, and it's been about 2 years since the cross-drilled crank was installed. Methinks it helped...no sign of failure yet.

 

porschephile have you been in to inspect or change your bearings since the rebuild?

 

I replaced the rod-bearings on my 951 at 125K-miles. The #2 bearing was worn with maybe 10K left. This was on a car that had seen 3-years of 7000rpm race-track duty. So I'd recommend everyone inspect and replace their rod-bearings at 100K if you track it. As to the improvements with perp-drilling, oil pick-up extention and oil-pan baffling that I did, I'll have to wait another 100K miles to make a direct comparison.

Personally, I still think there's something internal to the crank that's the problem, gonna devise some experiments to measure actual flow to individual journals to test this hypothesis.

Brendan, the design I had was actually for just the hole. The shop ended up having a special bit that does the drilling and chamfering in a single operation. I'll check on what their cost would be for a V8 crank (we won't tell them it's from a Porsche). They also recommend polishing the journals as they tend to be rougher than average for some strange reason. Honda cranks are simply jewelry dressed up as auto parts...

 

Danno were your oil pickup extension and oil pan baffling upgrades your own custom work or did you get those from somewhere else? my '83 has the old baffling that as I understand it should be upgraded anyways and I think I recall someone makes an aftermarket one.

 

I just brazed a 1/2" strip of 0.020" thick shim steel around the oil-pick up to lower the pick-up level. Simple job really. Then the oil-pan baffle, I bought the udpated 951S version from another Rennlister that had an extra. Total cost was about $150 including the brazing torch and supplies.

 

did you happen to take any pics of it when you did it?