Pumba

Gentlemen,

Over the past few days I have had an opportunity to discuss LS gerotor oil pumps with an engineer who designs and tests such pumps.

Before I go any further, I need to warn that some of the data I am going to present will confound and upset some of you. So, if you decide to read on, don't throw darts.

• All three of the Detroit OEMs are working on improving their crank mounted gerotor pumps.

• Ford is having problems with their supercharged modular engines and gerotor oil pumps. It seems that the belt load of their supercharger is deflecting the snout of the crankshaft and putting a high load on the inner gear of the oil pump. So, if you have or are looking at putting a supercharger on you LS engine, be certain that you have a good fully counterweighted, internally balanced forged crankshaft, with the appropriate ATI damper on the snout to minimize the deflection of the crankshaft and its snout.

• Chrylser is also looking at the design of their gerotor oil pumps on their HEMI engines for improved output.

• GM is looking at improving the output of the gerotor oil pump for the LS7, LSA, and LS9 engines.

The following chart gives a comparison of oil pumps that are available for the LS engine:


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It is obvious from the data that the Melling M10335 or M365 pumps are a major improvement over the original and even the improved LS7 and LS9 oil pumps. They are available from JEGS and Summit.

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If you are having an engine built that will use a gerotor pump have your engine builder install either the M10335 or M365 pump. For less than $150, it's a great engine life improvement.


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STB

I envy your discussion with a gerotor engineer. I appreciate the post since I have been looking at the design of the gerotor for a few years ...... and trying to figure it out.

Is the factory service manual, or whatever it is called, which shows the inner workings of the engine as well as how to repair it ..... assembly tolerances, wear tolerances, torque values, disassembly/assembly with step by step instructions readily available?

Interesting design the gerotor is ............... .

Thanks for the post

Supercharged111

The fact that the cavitation point is only held off until 6200-6500 is a bit concerting when your car's redline is 6600. With the bypass set at 35-40 for my LS6, the fact that I see more than that means that the volume is sufficient to overwhelm the factory bypass? How much pressure do the engineers actually want then?

Pumba

The following is a graphical representation of the data shown earlier in tabular form. You will note the cavitation points:

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STB

What do the vertical numbers refer to?

TIA.

Pumba

Engine RPMs.

Supercharged111

Would the Melling 10296 be enough to pump the pan dry? I'm about to install an oil cooler, which will drop my pressure, and I figure the 10296 with its higher volume and pressure should be able to make that up. . . but I don't want all the oil to sit in the heads.

leadfoot4

Not to be an azz-hat, but are you sure about that?


"STB" referred to the "vertical" numbers, the numbers to the left of the graph, that run up and down...they look like oil flow numbers to me. The numbers on the bottom of the graph, that run left to right, the "horizontal" numbers look like engine speed......