Why did Porsche engineers/management choose a dry sump system for the 901?

[Markus33]

I'm aware of it's benefits: The dry sump lubrication system is the ultimate oiling system for internal combustion engines. The simple fact that all Formula One, Indy cars, Le Mans and Sports Racing cars as well as Super Speedway Stock Cars use dry sumps, proves this point. Technical Description - Dry Sump Systems

My understanding is that recent/current P. management decided to do away with it mostly to cut costs.

But why did Porsche engineers/management decide to use a dry sump system in the original 901 design in the first place? The 356's didn't have it, outside of those with the four cam Carrera motors, that is. But I've read that the 901 wasn't really designed to be a racing car, at least initially. But if that were so, why have a dry sump system from the start?

Thanks,
Markus

[matt demaria]

I think because of 2 reasons:
1. A 5 quart oil pan would mean that they would have had to raise the engine in the body to gain the ground clearance required by german law. This would have ruined the rear body lines of the car.
2. At the time jaguar brought out their C type (or d type I forgot). The only way that car could compete in the endurance races was with an enormous oil pan to compensate for the oil consumption loss during the races. I think Porsche wanted to ensure the engine didn't run out of oil for their endurances also.

By the way they did build a wet sump engine. I believe there are pictures in excellence was expected. They played around with wet sump, dry sump, overhead valves, and overhead cams. The prototype carbs were webers from a Lancia which were longer and did not have the offset manifolds. Then the decided to go to the single barrel solexes which were the only dry sump carbs ever made.

[r_towle]

Bottom end clearance with no oil pan.

Just a guess, plus they had years of experience with dry sumps in racing already, and they knew it was a better idea for a new motor to start it right from the beginning.

[Flieger]

They intended to use the 911 engine as a race engine (904 and more) and they didn't see the benefit in making a different setup for the street version. Hence the dry sump, center-lube cams, etc. Much like the Carrera motor came from racing to the street cars, so the 911 motor was to become the workhorse racing powerplant for the forseeable future.

[Elombard]

Does the new 991 GT3 coming out have dry sump? I cant remember.

So the 9A1 ( I think this is not the correct designation for the DI motors any more) motors are not dry sump? I have not been paying attention.

[Bill Verburg]

Originally Posted by Elombard

Does the new 991 GT3 coming out have dry sump? I cant remember.

So the 9A1 ( I think this is not the correct designation for the DI motors any more) motors are not dry sump? I have not been paying attention.

No, it is a modification of the 9A1 DFI motors used since '09 in Boxster, Cayman and Carrera which is a modification of the original 996/Boxster motor introduced in '97

the 991 GT3 will be the first GT3 to not use the Metzger engine which though water cooled was derived from the original air cooled 911

[Flieger]

"integrated dry sump" i.e. an oil tank where the sump would normally be. I guess there is a divider plate to keep oil from sloshing around so much but it doesn't seem to be very deep so the engine doesn't have to be raised much?

[Elombard]

I wonder how many quarts of oil the 991s hold?

[prebordao]

As a bonus, the dry sump makes it less likely to loose all your oil if you go off-road "unexpectedly".
Ask me how I know...

[Allen_70S]

From “Porsche 911 Story – The Entire Development History” by Paul Frere, Tony Dron, Ninth Edition, 2013:

“Oil surge is a particularly difficult problem with flat engines. Fast cornering tends to throw oil into one bank of cylinders, unless the sump is deep enough, which means raising the engine higher above the ground. A flat sump causes the oil pump intake to be starved when the oil is centrifugated by side forces. In the pushrod engine of VW derivation, a system was developed incorporating two oil pump pick-ups and inertia valves closing whichever was likely to aspirate air rather than oil, but for the new six a larger volume of oil was wanted and, though a wet sump engine had been on the drawing board, it was decided to adopt a dry sump lubrication system. This had already been used by Porsche in the four-cylinder Carrera and in the eight-cylinder racing engine introduced in 1962 for Grand Prix and sports car racing.”

Al