Oil pump gears... with a twist!

[JDEstill]

In another thread we were talking about oil pumps. Stock oil pump is rather inefficient. Gerotor pump is efficient, but the projects out there to weld an 87 timing chain cover top half to a 3800 timing chain cover bottom half are a bit on the tough side for the average guy. How about different design pump gears? The straight gears we use are essentially the same as a Roots blower, also known for their inefficiency. If we had gears that were a twin screw design, pumping efficiency would get much better. Think Eaton/Magnuson type superchargers. If the rotors in our oil pumps looked like the rotors in those types of superchargers, it would work better.

Now my first thought was that this would be cost prohibitive, the difference in cost between regular parts house gears and these special gears would be too much for anyone to bother buying them. Now I wonder, with the CAD/CAM capabilities these days, maybe it wouldn't be so bad? A good project for RJC maybe?

John

 

[lazaris]

Great Idea!

 

[SNOWBIRD]

Sure ,would Be A Great Project For Rjc ..he Would Pour In Thousands Of Dollars In R And D And Then Someone Would Get One Of His Pumps And Ship It To China To Be Copied...wecome To The Business World

 

[ronbuick]

Maybe a patent that he could get on this, who knows!

Ron

 

[Race Jace]

In another thread we were talking about oil pumps. Stock oil pump is rather inefficient. Gerotor pump is efficient, but the projects out there to weld an 87 timing chain cover top half to a 3800 timing chain cover bottom half are a bit on the tough side for the average guy. How about different design pump gears? The straight gears we use are essentially the same as a Roots blower, also known for their inefficiency. If we had gears that were a twin screw design, pumping efficiency would get much better. Think Eaton/Magnuson type superchargers. If the rotors in our oil pumps looked like the rotors in those types of superchargers, it would work better.

Now my first thought was that this would be cost prohibitive, the difference in cost between regular parts house gears and these special gears would be too much for anyone to bother buying them. Now I wonder, with the CAD/CAM capabilities these days, maybe it wouldn't be so bad? A good project for RJC maybe?

John

We just got back from the SEMA show and it was very inspiring. Lots of new ideas and products. great stuff. It did however give me a little sick feeling when i saw tons of Chinese looking people taking very detailed pictures of all the products. It is everyone's problems not just ours. US patents don't seem to even bother them and a US patent only gives you the right to sue. you can't really sue someone from china.lol We decided to not let that get us down and just go on doing our best to invent new innovative products.

now on to the thread. Let me explain how they make the current gears. The gears are cold drawn/extruded in that gear shape and just simply precision parted off. the only real machine work is done on the coast gear's ID. This makes them very very cheap to produce. The helical cut gears have to be cut on a gear cutting machine. So they are very difficult to machine. you simply can't cut them on a typical CNC machine because of the surface finish that must be maintained to ensure a seal between the two rotating gears.

The reason they cut helical cut gears over straight cut gears in gear boxes is noise reduction.

Adding a small helix to the gears will do nothing for the efficiency of the pump. adding a large or steep helix will make them not work. The screw type blowers differ from the roots style gears in location of the inlets and outlets and how they work. the roots inlets and outlets are centered on the gears and the screw types are toward the ends of the gears. in other words the differences of the designs are just more than the gears.

Duttweiler and White racing do make an alternative style oil pumps. I have never seen one so i don't know that much about how they are different.

Hope this helps.

keep thinking though guys, i really appreciate the good ideas like this one.

 

[TurboDave]

Duttweiler and White racing do make an alternative style oil pumps. I have never seen one so i don't know that much about how they are different.

Hope this helps.

keep thinking though guys, i really appreciate the good ideas like this one.

I have, excuse me, had a Duttweiler pump. The pump isn't any different other than using the longer higher output gears. The lower housing however is the big difference, allowing for external plumbing.

 

[Race Jace]

the reason the roots type blowers are inefficient is because they add a lot of heat to the charge air. This does not really apply to the oil pump scenario.

So the reason the duttweiler system is better is because of better routing of the oil passages and not more efficient pump config.

 

[JDEstill]

bummer. Oh well, I figured it wouldn't be practical.

To clarify a couple of points though, I didn't really think about the configuration of the pump inlet and outlet as being an issue with the gears, but now that you mention it, you are right, it is. With the way the pump is fed at the end of the gears, that wouldn't work with twisted gears. However, one of the items in Earl Brown's oil pump setup article is drilling a new inlet hole down at the other end of the housing from the existing inlet, and I believe that new inlet hole with the existing outlet would let a twin screw design work properly. Moot point though.

The other thing, and this is just nit picking (sorry Jason), you said "the reason the roots type blowers are inefficient is because they add a lot of heat to the charge air". Well, not really. Adding a lot of heat to the charge air is a *result* of the blower being inefficient, not a cause. Root blowers are inefficient because they do not actually try to compress anything, they are made to just move a constant volume from inlet to outlet. The only reason the outlet pressure rises is because the blower is moving air in faster than it can get out via the engine. A twin screw design, however, is a lot more efficient because it is designed to actually compress the fluid between its rotors.

Now, for an oil pump, is that going to make a difference? Granted, not a big one. The low efficiency of the existing pump doesn't cause a big temperature rise I think, though I haven't run the numbers to see how much. But it does chew up a few more hp to drive it, and maybe someone looking for that last extra hp would benefit from a more efficient pump. I don't recall how much hp it takes to drive our pumps. I should figure that out...

John

 

[ijames]

Apparently the latest method of making oil pump gears is sintered powdered metal. Unfortunately Melling (I think) is having some quality control issues breaking gears with their new units, and they haven't gotten all of the "billet gear" phrases out of the catalogs yet :-;. Definitely not a process to prototype in a backyard garage but it would be possible to make a helical shape once the molds were perfected. Anyway, for more on this see: Melling no longer using billet gears in any pump!! - Speed Talk and Schumann Oil Pump report - Speed Talk

 

[Race Jace]

cool great info guys.