Doc

Well after two good problem free years of racing my 86 951, the hammer finally dropped. ...I spun a rod bearing this past weekend (Read- rebuild time) and I'd like to prevent this from happening again.

The standard seems to be adding baffles to the stock pan however I have a friend that went with an S2 pan on his car, (said the problem was fixed on that year and would do the same as adding baffles.)

The question is, which is better. Any first hand experience?

Thanks in advance.

P.S. I know about "Accusumps" as well as block and or crank work etc. however the budget is rather limited these days.

Outlaw952

I have talked with a mechanic, who by the way also races 911's, about this very subject. His recommendation was that if you are racing your car (with suspension stickier than a street setup), you should add custom baffles to your pan. He explained that even the Turbo S and NA S2 baffles are not designed to help with scavenging while the car is cornering with the types of g's you will experience in a race. He recommended that I let him add a baffle to my pan with a one-way trap door, which would allow oil to flow to the pick up tube, but under hard cornering would close the trap door and not allow the oil to slosh away from the pickup. Sounds simple, but also sounds effective.

Doc

I am familiar with the baffling process, what it entails and why however, what I am hearing is it sounds like one vote from your mechanic for baffling vs. an S2 pan.

Just for the record, which shop does he work for?

Also (to all) I've talked with Derek Huntley (Owner, Huntley Racing- <a href="http://www.huntleyracing.com/" target="_blank">web page</a>) and he feels the problem is not so much with the pan, but the crank itself. He tells me they have a $1000 process of machining and "knife edging" etc. that will eliminate the problem all together.

Being that I spun a rod bearing, I’m sure I'll have to send the crank out anyway, so suppose the question is, do I go with Huntley’s method, *AND* baffle or just one or the other? If so, which one?

Thanks again in advance!

Danno

Doc, sorry to hear about your car, saw another 951 do that exact same thing at Sears Point a couple of months ago.

Yeah, I suspect the #2 rod-bearing is an oil-passage issue with that one journal alone. Nothing else can explain why it's just the #2 and not any of the others as well.

You can get that crank work done for a lot less than $1k. I know one guy that has performed the 90-degree offset secondary hole on the rod-journals (on the very outer tip) with the crank in the car even! Knife-edging & balancing the crank shouldn't be any more than a couple hundred bucks since this is such a common procedure. Call around to several machine shops.

R.B.

Hey Doc,

Danno is right about shopping around. I found some local machine shops that will regrind, polish, and magnaflux for $120-$150 Cdn. If they weld up the journal it's an extra $70.

I have not asked about the drilling the extra holes or knife edging. As far as drilling the holes, I am not confident enough about how to do the procedure to tell the machine shop what to do. And as far as knife edging, I am not sure that there aren't any "cons" to the procedure for a street car.

R.B.

Toolmaster

All -

As usual, I concur with Danno. The real issue here isn't that there's not enough oil, etc, but that the oil passage to the #2 rod bearing is almost vertical.

What happens is that when the pickup gets uncovered (not a great thing to have happen and usually due to not enough oil in the pan - as in less than what's SUPPOSED to be in there, or foaming, or whatever other reason) an air bubble gets trapped in the vertical passage preventing oil flow to the bearing, resulting in a very unhappy Porsche owner.

Overfilling the pan doesn't always help - as even with 1/2 quart more oil in high-g situations even that amount can be forced away from the pickup.

Baffles on the pan sorta help, by preventing the pickup from being uncovered. The later pans had different baffle inserts (read the Rod Bearing procedure on the Rennlist TECH site for the numbers, etc) which helped the issue a smidge, but all of these solutions are more fixes to the symptoms, not a solution to the problem.

The only solution that I'm aware of is re-drilling the crank/block to fix the vertical shaft. Huntley's rifle/perp drilling seems like it's the way to go, but I'm 100% sure that other "Tuners" out there (like Milledge for example) have other ways of fixing this issue.

If you want to be really slick, then get yourself an 89 or later block... There's a casting difference in them that helps reduce the problems. It doesn't FIX it - as the crank itself needs a little work, but it helps.

My opinion from my experience only. Take this information as just that. (To hopefully prevent having to wear Nomex now...)

HTH!

Doc

Hey guys,
I have found a better deal on crank work from a highly reputable shop, $569 from Armondo at Custom Crankshaft in Redwood City, CA. That includes cross-drilling and knife-edging.

I'm also going with Jerry Woods at Smart Racing Products for the pan baffleing [$320] and for extra added protection, Jon Milledge of JMEngines for an Oil Air/Foam seperator/accumulator [$460].

mumzer

Doc;

As an FYI...I have had Armando do cranks in 3 TransAM motors over the years...no not pontiac street cars, SCCA TransAM race cars (ie 750 hp small block fords that we turn 9000rpm)

A better crank repair and machine shop does not exist. He is an artist. Your money is well spent.

H Dog

After perusing one of those racing catalogs out there, it looked to me as if an Accusump was only a $400 proposition, tops. It seems to me that this is a more bullet proof solution than machining your crank or swapping blocks, plus it costs less.

What am I missing?

Danno

Partly because the Accusump fixes the symptoms (insufficient oil), leaving the original problems & causes in place. While the crank-drilling and new block fixes the cause & problem that started it all, obviating the need for an Accusump at all.

Doc

Mumzer (and everyone else)

Thanks for the input! I'll keep you guys posted on the progress.