Dry Sump system for stock 944 Turbo

[Mike Pons]

I am interested in installing a dry sump oil system on my 86 2.5 951. Does any one know where I can find the parts or kit? Has anyone installed a dry sump on their 951? Thanks for your help.
Mike

[Dan Chambers]

Mike:

I've seen a couple of 944-Spec cars with Accu-sumps mounted in the spare-tire area of their racers. Other than that, I'm not sure about how or where you could put a "dry-sump" or auxilary oil tank.

Try giving Tim Comeau a shout at Comeau Racing regarding this idea. You might also talk to Black Forest, Dieter's, or Mind Over Motorsports about a more advanced oil-circulation / oil tank system. They may have some ideas as well. (I know that one of our 944Turbo racers has a fairly trick oil-pan system with baffles, special pick-ups, yadda-yadda that, I think, Black Forest may have intalled )

Good luck!

[Mike Pons]

Thanks Dan Chambers for your help. I will take give your recommendations a call and see if they can help me. See on on the track!
Mike

[Jad]

I am curious as to why you want a dry sump? Enduro, cooling or have you had starvation problems?

Other than high rpm starvation, caused by crank design, not the wet sump, I haven't heard of any oil problems on 951's.

[Mike Pons]

Hi Jad
I threw a rod during a session at Las Vegas International Speedway. It appears that it may have been caused primarily by using second gear too much in a particular sweeper (shaped like an omega)which was added to the infield by POC for tha weekend. Third was too long to maintain speed through the turn. The problem was keeping rpm low enopugh to avoid the rev limiter. During my search for a second engine, Jon Milledge recommended to dry sump the enginbe to increase the reliability, strength and longevity of the rod bearings. So I have been looking because he became ill and is unable to fabricate what he recommended.

[Jad]

I admit I have limited knowledge on the internal workings of engines, but generally speaking 944's destroy the #2 bearing because the centrifical force is too great above ~6000 rpm and the oil gets pushed to other places instead of the #2 bearing. It is not a starvation problem so I do not believe a dry sump will change the situation but will cost a good deal of money. So just be sure you really know what is going on before spending money to fix the wrong problem.

[Mike Pons]

Thanks for your recommendation Jad. I am not too knowledgeable either and was simply following the suggestions of one of the better known racing engineer Guru's of 951 and 968. However my racing mechanic Mark Hergesheimer is one that does not like to spend on anything not required. I also heard from Tom Charlesworth the tech director for PCA who also suggested a different fix which he has used for his 951 Cup racing engines and that was to cross drill the crank. Which is most likely what I am going to do just to get back in the game quicker. I have been off track for three months and I am beginning to show serious detox. Just kidding. Thanks again for your help.
Mike

[Greg Phillips]

The 928 has similar issues with the 2-6 rod bearing failure- as you have noted, there is no ceoncensus on the fix. Here is some more info to review from Marc Thomas a 928 engine builder:

From: Marc Thomas [mmthomas@ix.netcom.com]
Sent: Friday, October 27, 2000 4:32 PM
To: 928
Subject: [928] 2/6 rod bearing failure

David,
Our testing has shown that the 2/6 rod bearing failure is caused by TWO
issues, and the main reason for the failure is not the one most commonly
thought.

We have spent years understanding the issue, 3 engine builds testing
"theory" and teardowns and lots of engineering and here is the summary. How
good is the summary, well, they are good enough for Porsche AG to purchase
our solution for their racing 928 customers!

First, the 2/6 oiling path is the least contributing factor to the failure!
This is the common misconception.

The main factor is simply oil starvation, and the 2/6 rod bearing feed off
the crank is the first to get the gulp of oil/air.

Where does the air come from, well if you are cornering at 1g, the the oil
in the pan is at a 45 degree angle, and depending on oil level, will uncover
the pickup....hence the air!

The secondary factor is from off angle oiling of the 2/6 journal off the
crank. This is a minor issue and if oil pressure is sufficient, it is a non
issue at any rpm.

The oil starvation, or lack of oil in the pan is caused by the fact that oil
is pumped into/upto the head in large quantities by high rpm and the head
acts as a oil "pan" of its own. The crank also spins up a batch of oil and
keeps it in suspension, especially at high rpm. This oil cloud circles the
crank and is the reason most race engine have "scrapers" in the case. Up to
two quarts of oil can be circling the crank at high rpm! In some cases it
can be more as the S4 is known to "pump" oil up the oil filler tower and
keep it there!

When there is not enough oil in the pan (caused by the high rpm pumping of
oil to other areas, like the head, etc.), then under cornering at 1 g, the
oil pickup is uncovered!

So, the worst thing you can do to your engine is this...a 6500 rpm corner
entry, a 1 or more g corner force while maintaining 6000+rpm...you are sure
to pick up some air...and do it enough times, the bearing will fail.

It will happen more frequently and sooner on a S4 then on an early engine
with the same cornering capability due to the fact that there are less
places for the oil to stay in the head and the paths in the head are
smaller. So more oil stays in the pan.

The solution as originally develop by DEVEK is as follows...use our Accusump
systems! The DEVEK Accusump systems have two levels, street and race and
each one offers a different level of protection, but only for so long.
Approximately 10 - 17 seconds depending on oil type, temp, etc. These are
the systems that are purchased and recommended by the factory.

An addition item is to decrease the amount of oil available to the head by
increasing the spring pressure or my favorite, decreasing the feed orifice.

The other method, again as developed by DEVEK (by the late Bob DEVore) and
currently used by other racers, is a simple dry sump system that uses the
original oil pump to feed the engine from a remote tank, rather than the oil
pan and a scavenger pump to fill the tank...

And of course, you can just dry sump the system externally and depend on no
stock oils systems.

On OUR Scat stroker cranks, we simply pick up oil off the number three main
bearing to make is a straight shot to feed the 2/6 rod bearings...so as some
one correctly pointed out, it is routed like a chevy. This is unlike our
drilled cranks, which have a modified oil pathway.

I hope this clears up most of the misconceptions about a weakness of our
engines and clarifies why some folks believe that the engine will last
longer if the rev's are lower.....less oil pumped out of the pan.

Oh, by the way, can it happen to a non racer? YUP, if your oil level is
low, and you are running at 6000+ rpm for a hundred miles of so...it can
happen. And this has happened.

More information is available in our catalog or give me a call or email....

Warmest Regards,

Marc

--
Marc M. Thomas
DEVEK
The White Car
450hp/470tq on the ground
210 mph 'on the street
THE fastest 928 on the planet.

http://www.devek.net

[Dan Chambers]

Thanks for your recommendation Jad. I am not too knowledgeable either and was simply following the suggestions of one of the better known racing engineer Guru's of 951 and 968. However my racing mechanic Mark Hergesheimer is one that does not like to spend on anything not required. I also heard from Tom Charlesworth the tech director for PCA who also suggested a different fix which he has used for his 951 Cup racing engines and that was to cross drill the crank. Which is most likely what I am going to do just to get back in the game quicker. I have been off track for three months and I am beginning to show serious detox. Just kidding. Thanks again for your help.
Mike

Mike:

To follow-up; many 944Spec and non-Spec 944 track cars have their crank cross-drilled for reducing the starvation risk. That being said (and I tell all 944 guys/gals this) there is no reason to drive a 944 at 6100+ RPM's for any length of time. Never. Ever. Period.

In a N/A 944, the power-band drops off significantly after 5750 rpm. If you think taking the rpm's to 6200 or 6400, or 6600 (rev-limiter in most N/A 944's) is going to give you a better rpm in the next gear up, you're gambling with destroying your engine for no good reason. Fact is, at 6000 rpm, you shift up to the next gear, you'll be in the low 4000 rpm range .... right in the lower end of the highest torque/HP band of the engine. 4000 to 5650 is the best torque/HP band of the 944 N/A engine. Higher rpm (or lower than 3800 rpm's) and you're out of the best power curve of the engine. So, why are you wasting valuable time and power at 6200+ RPM when you could be in the next gear up pulling more torque/HP?

I know a little less about the 951's. However, based on the limited time I've been in them, I've found that anything over 6200 RPM is a waste of time, power, and boost. If you shift the 951 at 6100 rpm, you're most likely still in the HP/Torque/Boost range to pull aggressively, through the higher gear, to 6200 RPM... again, running in the best power band of the engine + boost.

Since 2002, I've shifted my stock 944 at 5800 to 6000 rpm up to the next gear during competition. With 330,000 miles on my engine, I have no interest in hearing it go POP at 6400 rpm! Since 2002, I've consistantly placed 3rd or better in my class. I see no reason to turn constant 6100+ rpm's in my 944 when I'm winning competitions at 4000 to 6000 RPM's.

Just my 2-cents. Good luck with your engine re-build.

[TheStig]

Hey Dan, I agree with you totally! Let's not forget that the car has no breathability past 5500 RPM. I can compare upper RPM range powerband to a truck engine

[TheStig]

I admit I have limited knowledge on the internal workings of engines, but generally speaking 944's destroy the #2 bearing because the centrifical force is too great above ~6000 rpm and the oil gets pushed to other places instead of the #2 bearing. It is not a starvation problem so I do not believe a dry sump will change the situation but will cost a good deal of money. So just be sure you really know what is going on before spending money to fix the wrong problem.

Hey Jad, I read an article in some magazine (maybe Excellence or GT Purely Porsche) regarding this issue. They had mentioned the dry sump conversion, but still wouldn't solve the bearing issue. I wouldn't rule out a design flaw on the 944, but maybe perhaps that the car just wasn't meant to exceed anything over the power climax of 5500-5600 RPM. Cross-drilling the crank helped lubrication, but tests were inconclusive as to the durability of the engine at that high of an RPM. The car is not exactly a small displacement 4 to be revving up to 8,000 RPM. Hell maybe displacement may have something to do also with the bearing issue. Large displacement 4s are known for vibrations (hence Porsche's reason to also incorporate balance shafts into the 944 crank case design.)

Moral of the story: want more power? Go buy a 930 or 928,

oh and avoid Boxster at all costs... <--Kidding