FennLane
Materials
- Jul 3, 2012
- 93
Oil pumps installed in Porsche 911 engines are simple external gear pumps which operate a dry sump lubrication system.
The pressure pump section produces around 70psi and the scavenge section has around 2 x greater length than pressure section.
These pumps are generally quite long lived and quite reliable but no spare parts are available and no specifications are provided.
Recently one or two companies have been offering rebuilt pumps and claim to offer pumps with both increased flow and increased pressure.
The only modification that seems to be carried out is a small porting enhancement on the intake side of the pressure section.
Cavitation does not tend to occur in the pressure pump and I struggle to understand how intake port smoothing helps the increase the flow of a fixed displacement gear pump by 20%, which is the claim.
I don't believe any changes are made to either the radial or lateral clearances and improving spill by such an amount at 70% also seems optimistic.
No test data has been published and I believe that the only tests carried out is flow into an empty tank.
When I ask questions I am told that no data will be given as I am only interested in disputing the claims.
I haver to say I don't understand how these claims are met but would be happy to listen to any sensible explanation.
I do have some experience of building a relatively large number of pump test rigs and the improvements made do seem excessive.
Can anyone offer a sensible explanation which will eliminate my doubts?
The pressure pump section produces around 70psi and the scavenge section has around 2 x greater length than pressure section.
These pumps are generally quite long lived and quite reliable but no spare parts are available and no specifications are provided.
Recently one or two companies have been offering rebuilt pumps and claim to offer pumps with both increased flow and increased pressure.
The only modification that seems to be carried out is a small porting enhancement on the intake side of the pressure section.
Cavitation does not tend to occur in the pressure pump and I struggle to understand how intake port smoothing helps the increase the flow of a fixed displacement gear pump by 20%, which is the claim.
I don't believe any changes are made to either the radial or lateral clearances and improving spill by such an amount at 70% also seems optimistic.
No test data has been published and I believe that the only tests carried out is flow into an empty tank.
When I ask questions I am told that no data will be given as I am only interested in disputing the claims.
I haver to say I don't understand how these claims are met but would be happy to listen to any sensible explanation.
I do have some experience of building a relatively large number of pump test rigs and the improvements made do seem excessive.
Can anyone offer a sensible explanation which will eliminate my doubts?