High volume vs. high pressure oil pump

[Valkman]

Lets Talk About Oil Pumps!

 

[moper]

Until you go to adjustable rockers.

There is always pressure up there.

Still no pressure beyomd pushing it out of the holes, and that is only for about 30 degrees out of 720. What did happen u think? Yeah u change the rockers on the shaft and the whole system changes? What do you think spray bars do in big blocks with indy heads? Only change would be pushrod oiling, which still only splaash feeds the rockers...

 

[Duane]

It´s all about the clearances inside the engine. If an engine has tight clearance, then the stock volume oil pump is sufficient to produce enough pressure. If an engine has got loose clearance, then sometimes the high volume pump is necessary to produce enough pressure. If you put a high volume pump into an engine with tight clearance, you may end up with high oil pressure up to the point of where the relief valve opens.....and some of the oil flows under pressure directly back to the sump (lost power).

In my opinion, in most cases, if an engine is built right, a stock volume pump is sufficient. If you have some kind of valve spring spray bars or other "leakage points" like lifters with oil holes to lube the cam directly, then a high volume pump could be beneficial.

Michael

I see the comment that when the relief valve opens that oil is sent "back to the sump" made all the time. Can someone please explain exactly where on the pump the oil is sent to the sump. I believe this info is incorrect and that oil is bypassed back to the pickup inlet inside the pump itself. Please correct me if I am mistaken.

Duane

 

[Darthomas]

I see the comment that when the relief valve opens that oil is sent "back to the sump" made all the time. Can someone please explain exactly where on the pump the oil is sent to the sump. I believe this info is incorrect and that oil is bypassed back to the pickup inlet inside the pump itself. Please correct me if I am mistaken.

Duane

You are correct.
The oil "short circuits" in the pump itself if the overpressure plunger is moved back in the bore.
When this works correctly, no problem.
But the plunger can get stuck in the bore by oil varnish buildup.

 

[360duster]

Ok Guys, my fault....the effect is the same.

Michael