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External Oil Pump
Often times during the year I will go to the local circle track to watch the modifieds or the Busch East guys. All the engines in these cars have external oil pumps. They run off a belt outside the engine.
My question is, do any Cobra owners have their engines set up that way? What are the advantages and disadvantages of such a set up? To me it seems like a good way to take load off of the distributor gear. Any thoughts? Bob |
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Bob
They are a Dry Sump .....and we use one on KMP 259..... The benefits are that it allows the oil to be stored in a Oil tank that will not be affected by the car going around a corner and having oil slosh to one side there by loosing oil pressure..... We have found that they allow us to go on any race track and not be concerned with loosing oil pressure in a Oval type of turn..... They also keep the amount of oil in the crankcase to a minumium and keep the oil out of the way of the spinning crank..... We've used Dry Sumps for years and they work extremely well and maintain pressure in all situations.... And yes there is less of a load on the distributor with out a oil pump to drive..... http://www.clubcobra.com/photopost/d...0/DSC04765.JPG Morris |
Can I assume that the external pumps are always used with dry sump systems?
Bob |
No, they aren't. All that must be inside the sump is the pickup, then the oil is routed to the pump. An external pump used with a wet-sump system is typically used to evacuate the top end and to pull a vaccum in the crankcase. I cover this type of setup in detail in my new book, The Racing Engine Builder's Handbook. Gee, another chance to hype my book.:LOL:
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-Dean |
Bob,
As already stated, they are not all Dry Sump systems. Keith Craft built a wet sump system using an external pump and that car was for sale outside of Memphis (Superformance). I liked the concept and will look at that option hard if building another Cobra motor. To me, the true benefit isn't a ROAD COARSE lateral load & oil supply requriement rather the lack of stress on the cam shaft and gear. Good thread and let us know if you swap it out and eventually like it. |
Another advantage (I think) is the ability to turn the pump without turning the engine (pre-oiling). This would be something one could do following long periods of inactivity.
Bob |
I believe the traditional (426) hemi used an external oil pump. The Viper definitely does.
Depending on your definition of external, the Ford Mod's and Chevy's SBC both use gerotor oil pumps that are mounted on (around) the crank. They are not located in the sump nor driven by the distributor. The biggest difference between an external oil pump and a dry sump system is usually the number of 'stages' present. As mentioned above, one big benefit of a multi-stage dry sump setup is to draw oil directly to the pump from high up in the engine, as well as being able to use a stage for vacuum scavenging of the block. |
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