Any hands-on experience with the GM-90 variant?

[solarguy]

Anyone have hands-on experience with the GM-90 variant?

I am specifically interested in the pressurized oiling system.  How do they get pressure to the crank journal/con-rod bearing?  Is this oil pump a gear pump or the regular old low pressure piston pump driven off a cam lobe?

Finest regards,

troy

[listeroidsusa]

The GM-90 engines from 6/1 through 12/1 have oil pumps and pump the oil directly to the rod bearing. The crankshaft is drilled as in an automobile engine and has an ecentric machined into the crank beside the counterweight. The lower portion of the oil pump is fastened to the side of the crankcase with a fulcrum pin. As the engine rotates the plunger makes about a 1/2" stroke. The oil pickup is located under the oil level and has a screen to strain the oil. This could easily be changed to a filter system. The oil is picked up at a height of a couple of inches from the bottom of the crankcase so any debris would be left in the bottom of the crankcase. A magnet is a good idea in any engine.

Mike

[solarguy]

Thanks Mike!

troy

[DirtbikePilot]

I have a 20/1 and I'm really pleased with it! It is so friggin cool....!! It does not have a pump, but it does have a rather unique oiling system to the rod bearing. I'll put some pictures in the coppermine gallery of the crank. It uses a ring that is u-shaped (in a cross section) to collect splash oil and send it to the rod bearing with centripital force.

[akghound]

Mine is a 16/1. Bought it from Mike at listeroids/USA, very pleased about doing business with him. It has the dipper just like the one pictured by DirtbikePilot but also has an oil pump. I did have to replace the cam and idler gear in it. We run this engine up to 18 hrs almost every day, burning WVO. During the sub-zero weather it will run 24/7 for a few days at a time. The high temperature (weather) for today was 44*, inside the gen-shed it was 110*. By this fall I hope have it set up to provide most of the heat for our house. This has been one very good engine to get to know.
Ken Gardner

[DirtbikePilot]

How does that work? If mine also had an oil pump sending oil to the rod bearing, the oil would flow OUT of the ring instead of into it.

[hotater]

I think the rings act like a spoon in coffee and get the oil in a whirling suspension inside the crankcase with a blizzard of oil wrapping around the big end.  I know that's the way a solid dipper works.   The bearing is oiled from the top by oil falling down.

[DirtbikePilot]

Nope. Not in this particular case. A cross section of the ring would look like 2 "U"s facing eachother. The ring gathers splash oil and sends it to the rod bearing with centripital force by way of a hole drilled in the crank.

[hotater]

Makes sense to me...the oil, having less mass is caught by the more energetic ring and oil trapped is forced into the path of least resistance which is the hole in the crank.  The waste is probably 98% but all that's needed is the small amount injected.

[akghound]

How does that work? If mine also had an oil pump sending oil to the rod bearing, the oil would flow OUT of the ring instead of into it.

All the pump oils is the roller bearings on the crank, (The mains) not the rod bearing.
Ken Gardner

[DirtbikePilot]

I see, said the blind man..... What rpm is your 16/1 rated at? My 20/1 is rated at 22 hp at 800 rpm, 20 at 750 rpm, and 16 at 670 rpm.

[akghound]

I see, said the blind man..... What rpm is your 16/1 rated at? My 20/1 is rated at 22 hp at 800 rpm, 20 at 750 rpm, and 16 at 670 rpm.

She is rated at 16 hp at 1000 rpm. Due to the pulley size, I run it at just over 750 rpm so I'm getting about 12 hp useable.
BTW ... Running so many hours a day on WVO causes the rack in the injector pump to become sticky so I need to take it apart every so often and free things up.
Ken Gardner

[SHIPCHIEF]

I found that biodiesel also gummed up the injectors, if left to sit with biodiesel in them. (My engine is a standby pwere source, so I don't have a lot of run time)
Scott E