ET: Engine (Twin) Oil pump volume
- Thread starter Cyborg
- Start date
There are many variables, firstly how many revolutions per minute is the engine turning when you measure the flow?
0.625" diameter piston with about 1/4 to 1/3 in area machined flat on one side.......has a stroke approx. 1/4" and does a full rotation in 15 turns of the crank shaft.......Not dissimilar to squirting an oil can........
I figured it would be fairly low, given how long it takes for the oil in the tank to get up to temperature. If my brain wasn’t completely mush, I could measure the piston accurately and try and calculate the flow, except with the design of the pump, it only spurts out a portion of the oil in the chamber.
Thanks Dan, much appreciated. Exactly what I was looking for. I have a new pump sitting on the bench and may test it at some point assuming a test jig can be made in less than 1/2 a day.
But then, what would you do with the test ? You can have two start pumps for the Vincent or decide on a radical modification. Would that be worth it , I am not so clear about that, got the two start pumps. Remember there are lots of Jap engines around with total loss drip pumps, well total loss from drip is somewhat standard on Vincents as well . . . .
Vic
Vic
The stock Vincent pump works fine for most all engine set ups.......careful engine assembly with attention to the amount of crush on the ET 183 seals is very important......and parts that are made from the right material.......cams and followers are the big ones as they carry the highest load of any engine component, and oil drain grooves ground into the big end liners at the 9 and 3 o'clock positions to allow spent oil to drain easy and fresh oil to enter the big end.......Only the lunatics like me who like to push the engines a bit harder tend to run full pressure oil pumps or similar........I've actually set up my racing single to a 2 start pump, done away with the auxiliary full pressure pump........there are several reasons for this, but running a roller cam and followers you actually don't need as much oil delivery as you might think.......the roller cam has less drag than a flat tappet set up even though the valve springs are running much higher seat pressures than stock at around 140 lb's seat.......this with very light valve train parts used including our 6 mm stem titanium valves, 5/16" hollow chromoly push rods which are about 20 mm shorter than stock and again much lighter........I think our roller followers are only about 10 grams heavier than the radiused followers that Terry supplied with his Mk 5 cams.
The flats on the pumps are only acting as timing valves and have no influence on the volume displaced.
The feed pump is 0.625" with ¼" stroke, so 12.56cc/revolution. The pump runs 1/15 crank speed (single start pump) so 12.56/15 = 0.838cc/crank revolution.
You can convert to whatever unit is needed from there.
So at 1000 crank revs/min gives 1000 crank rev/min x 0.838cc/crank rev = 838cc/min = 0.8litres/min.
Therefore, for every factor of 1000rpm, the volume will be that factor x 0.838L/min.
i.e. @2500rpm volume will be 2.5 x 0.838 = 2.1L/min.
I wasn't all too clever with maths so if it's wrong then feel free to correct it.
The feed pump is 0.625" with ¼" stroke, so 12.56cc/revolution. The pump runs 1/15 crank speed (single start pump) so 12.56/15 = 0.838cc/crank revolution.
You can convert to whatever unit is needed from there.
So at 1000 crank revs/min gives 1000 crank rev/min x 0.838cc/crank rev = 838cc/min = 0.8litres/min.
Therefore, for every factor of 1000rpm, the volume will be that factor x 0.838L/min.
i.e. @2500rpm volume will be 2.5 x 0.838 = 2.1L/min.
I wasn't all too clever with maths so if it's wrong then feel free to correct it.
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Greg is right a standard pump is fine for a standard engine Ben runs a two start on the Goodwood Racer and the R will start to come out of the standard oil cap if the race is fairly long and needs a breather (and yes we have tried all the deflection dongles under the cap)
As I am building a twin with an unmatched timing cover I would be interested in the setting up of ET183 seals for optimum engagement
As I am building a twin with an unmatched timing cover I would be interested in the setting up of ET183 seals for optimum engagement