No way your getting 4 gpm through those passageways at 45 psi with a pressure drop through the oil cooler and related plumbing. Maybe .60 gpm at .50 feet per second. And thats pushing it really hard. You are fighting velocity concerning wear on the passageway and not to much dwell time resulting in burning the oil.

 

Yeah, that 4gpm had me raising my eyebrows, too. Not sure if anyone noticed, but that was a twin-cooled head he had on display. Is it possible for those systems to flow 4gpm of coolant through those heads? <me shrugs>

 

No,,,, lol

Think about a gallon of milk circ'ing the engine a minute on a oil cooled engine. And that's not even the total volume of the sump and system. That's impressive in and of itself. Through all those little passageways at 45 psi. It's impressive at 14 psi at idle a quart a minute on a fully warmed up engine. Just guessing.

I have access to a doppler unit that is used to measure flow in pipes from 2" to 48". Works great and is very accurate. But I can't make it work on the small tubing our bikes have. It will show me a graph of flow but the machine will not comment to calculations for the graph. On a fully warmed up engine at idle a gage shows me 14 psi at the discharge of the pump were the oil pressure switch is and the doppler shows me a low flow, but no numbers. Same if I go to say 2500 rpm a point set forth by HD to check oil psi. Psi reads 44 the graph goes up as it should. Rev to say 3000 rpm psi goes up to 48, graph does not go up much. Then the bypass valve opens up psi drops to the low 40 psi range alls well. The doppler graph drops a tad as it should. Now lets say i hold the throttle steady at 1700 or 2700 rpm. Bypass valve is not in play. Then out of the blue the top end changes tone and sometimes rattles. Psi is good for that given rpm but all the sudden the doppler graph drops. Sometimes by half. But never to the levels displayed at idle or just off idle. That tells me the pump is bypassing internally flow wise but still keeping good discharge pressure. And gerotor pumps are about psi.

All of this has been driving me nuts. My dealer does not even want to go there.Honestly it's out of there realm of understanding and explanation. Harley, S&S and Fueling will not even offer comment. And I've been wondering if this little phenomena my motor displays is not part of the sumping issue folks are seeing. But mine is displaying it in top end oiling. If the pump is internally bypassing there is nothing there to keep it from being put back in the sump or the crankcase. Could this be the reason for the new backplate and o-ring? I wish I could get numbers out of the doppler. And there is no real world way of adjusting this unit to correct the issue. It would take a doppler sized for the size of pipes, space limitations the pickup have to use to work right, temps and such.

I've had this crud running around in my head for well over a year or better. Seems like I've been testing this since I bought the bike in one fashion or another. Sorry for the blurt. That 4 gpm BS just triggered it I guess.

 

Nice to see David Spade's brother working at an HD dealer in Annapolis.

 

Very interesting Psyshack & the comment on the "extra cavity" or larger cavity space for oil purposes had me thinking on the lines of what you mentioned, LOL - I actually was thinking in terms of water pressure as you stated. That breather system is a joke as well - we all know that damn sponge will become oil soaked & the air/oil going through that mechanism will eventually lead to & in some instances pre maturely have oil dripping out of your air cleaner, Honda was running similar on their bikes in the 70`s off of the vent pipe out of the case with a return to the oil system & that thing never worked right, was just better to direct vent it - but today that's a no no!

 

 

Interesting article on the M8 oil problems in the latest copy of American Iron. From what I got out of it was HD is trying to conform to EU standards on pollution control, vapors, from getting into the atmosphere. The vapors can't be vented to the air. When the engine is run at high rpm's for a while the oil is beat into an oil vapor in the engine and starts choking the engine. IMHO HD wanted to sell bikes in Europe and didn't complete their home work in making things work, and leaving the faithful behind trying to figure it all out until warranty runs out.