Jim Clark

The failure point is the oil pick-up in the pan. If the pick-up strainer becomes uncovered and pulls air it drives the bearing failure. Cross drilling the crank helps for overall oiling but will not eliminate the factors creating the bearing problem. Oil pan and pick-up modifications are required for use with a stock pan but if you want to eliminate the problem all together than you have to go to a dry sump system.

Weston

Good point. I personally use only Valvoline VR1 20w50 in my 944-Spec car. It has lots of zinc (ZDDP), and I have seen it keep engines alive through an excessive amount of abuse... in one case, there was a gasoline fire directly below the oil pan, then the car was raced with a badly cracked oil pickup tube (lots of aeration of the oil) and with major overheating. The oil that came out afterward was this horrible sludge, and there was heat discoloration on the crankshaft around the rod journals, but the journals themselves looked good... it really only needed a fresh set of rod bearings. The bearings we pulled out of it weren't even all that bad considering what happened... just a tiny spot of copper showing on one, and wear that was evident of metal-to-metal contact on all of them.

I've also seen a number of guys racing on regular oils and have far less abuse (sometimes just overheating) cause them to completely trash their bearings and crankshaft, if not send a rod through the side of the block. When 944-Spec started growing pretty good in my region, we had a lot of people blow motors, but those of us running good oil with plenty of zinc in it have had great results. No oil will make your engine invincible, but after having seen several race engines torn apart, I'm completely sold on having plenty of zinc in my oil.

daigo

OK, but Canton doesn't make an oli/air separator do they?

924RACR

Rather impressive results with the VR1, Weston! Makes me glad I run it!

daigo - not sure what part it was that Millege specced, sorry... might just have to suck it up and call him...

hacker-pschorr

FWIW Valvoline makes three different 20w-50 racing oils. VR1 is "for the street" since it has the added detergents for a street car:

http://www.valvoline.com/racing/index.asp

I started using VR1 in my street 928. A lot of good testimonials and oil analysis out there, $3.89 per quart doesn't hurt either.

bgiere

good point on the diff between true Race oil and street oils...true race oils will have very little or no detergents in them...Redline or Joe Gibbs both have street and race-only oils available as well...

924RACR

Thanks for pointing that out, H-P!! I'd've never guessed... been using just the VR-1... wondering if I oughtta use the "Conventional" racing oil instead? Have also used and been happy with Redline, but it's so F'in expensive... $100 oil change on an Audi, c'mon!!!

Jim Clark

Anyone racing a flat tappet valve train without racing oil with high levels of ZDDP is just asking for trouble $100 a race for Redline or other race oils is cheap compared to the thousand of dollars for a new engine.

924RACR

I certainly do have the VR1 for my flat/solid tappet motor... problem I've seen is when they split down the side at 8000rpm

I was just wondering about the relative merits of the "Conventional Racing Oil" vs. VR1...

bgiere

Both Redline and VR1 will have 1200 to 1400 PPM of Zn and 1000ish PPM phos...at those levels you are fine for Porsche engines...The issue of synthetic vs. conventional can be decided by the oil temps your engine experiences...If you are consistently above 230ish degrees F you should definitely consider a high quality synthetic...I myself would use an ester based synthetic like Redline or Motul. Run a few races on your favorite brew and then send a 3 ounce sample in for testing.

924RACR

Yeah, I suppose that's what I REALLY ought to do...

Cheers, thanks for the advice...

joonas

How you set oil level with accusump? If you have 3 qurt unit add extra 3 qurt of oil?

What kind of valve you use on track? Manual or electrical?

924RACR

I use a manual valve, in reach of the driver. Oil level is set with valve shut before shutdown. My oil system capacity is now up to 2 gal (8 qts)! Plus of course a large cooler, filter and hoses.

joonas

When you close the valve how big is the oil pressure at that point and what is your precharge pressure?

924RACR

I don't recall the precharge pressure, but the oil pressure when I close the valve will typically be around 1-2bar (warm, but not hot, idle).