High oil pressure?

[Charles Rainey]

I would like to add my $.02 worth and I dont want to step on any toes. Oil pressure within a engine is determined by resistance that is "seen" within the engine,etc tight or loose clearance, small holes versus large holes, programmed bleed off built within the engine. The relief spring only sets the pressure that it opens to bypass the pump. Theoretically you would want your bypass to open ever so slightly in operation so that it is not cycling too often. Yes you are correct on oil viscosity being a determining factor also. Thicker oil will have more resistance, therefore more oil pressure. There has always been a misconception that a high volume oil pump is a no no. But that is not necessarily true as resistance to flow(clearances will determine how much oil will go thru the engine). I have heard many people say that it will empty a oil pan. The only way that can happen is you already have too much clearance and the pump is trying to meet the demand. Many smart engine builders use HV pumps so as to have enough volume later in life of the engine as clearances begin to get larger from wear. Of course race engines are normally built with a pump that just meets its demand as the engine will never "wear out". Synthetics has change many facets of oiling as we can do things now that we could not do even 10 years ago. We can now run closer to the edge than we ever could with mineral base oils.
Hope I did not step on any toes. Sorry for the long dissertation
Charlie

[TinSoldier 3215]

I put in 5/20 wt oil and let engine warm up to 150 and pressure was 60 and over 6000 stop at 75. Thanks Guys for all the HELP!!!!

[Mike Taylor 3601]

The high vol. pump pan dry myth,I found where that came from @ PRI show one time Melling had a bunch of bulletins,one addressed that it came from old Y block fords292,312 they did'nt have good drainback and not much restriction to top so it was possible to pump pan dry ,but stated most modern engines that was'nt possible.
Mike Taylor 3601

[BlueOval Ralph]

There where some SBC out there that had wrong crank drillings and would shut off oil at Habove 7500 rpms you would show pressure but could not feed rods

Originally Posted by Ed Wright

But, those were Fords. And sbc = Small Block Chevy, which has a great oiling system, unlike the early Fords. Myself, and many others building small block Chevys use the STD volume pump, modified for LESS volume. I also limit mine to 40 psi @ 8500 RPM. Bearings always look like new. Just replace them when I start to feel guilty about running them so long. If you ever build a sbc, call Larry Stewart Sr about buying an oil pump.

[Ed Wright]

"Many smart engine builders use HV pumps so as to have enough volume later in life of the engine as clearances begin to get larger from wear."

I would have to debate the "smart" part of that statement. SBCs typically run well over 200,000 miles with no oiling issues, way more than a race engine will ever see. The factory pump has plenty of reserve capacity to compensate for wear. Pumping the pan dry? There are other problems if that happens. What actually happens is the pump bypass stays open, peeing un-needed oil right back into the pan. Heats up the oil, wears the dist & cam gears, and wears the thrust areas on the back of the cam sprocket and front of the block, wastes power. I've seen those areas really chewed up over high volume pumps in local roundy-round engines. Absolutely no need for them.

Raph, I've been doing this for fifty years now, I have never seen a crank drilled like that. But, old as I am I haven't seen everything yet. :-)
Don't think a bigger pump would be the correct fix for that.

[BlueOval Ralph]

Nope it has to do with the angle of drilling vs Stroke> It will just flat shut the oil off, the SBC cranks I am talking about were made by BRC when they were doing cranks in TNN. Had a small block Ford that Crower did from a Ford Forging same way it was something to do with the cross drilling and if you put a plug in the one side it would crutch it but not totaly fix it thing go wrong about 7500 to 8000 if you stayed below that RPM they would last, but above it would shut oil off and spin bearings. There is a article some where on the Internet but cna not Find it FJ Smith might come in on this, I thinkd he had a couple of these cranks.

Originally Posted by Ed Wright

"Many smart engine builders use HV pumps so as to have enough volume later in life of the engine as clearances begin to get larger from wear."

I would have to debate the "smart" part of that statement. SBCs typically run well over 200,000 miles with no oiling issues, way more than a race engine will ever see. The factory pump has plenty of reserve capacity to compensate for wear. Pumping the pan dry? There are other problems if that happens. What actually happens is the pump bypass stays open, peeing un-needed oil right back into the pan. Heats up the oil, wears the dist & cam gears, and wears the thrust areas on the back of the cam sprocket and front of the block, wastes power. I've seen those areas really chewed up over high volume pumps in local roundy-round engines. Absolutely no need for them.

Raph, I've been doing this for fifty years now, I have never seen a crank drilled like that. But, old as I am I haven't seen everything yet. :-)
Don't think a bigger pump would be the correct fix for that.

[Ed Wright]

Thankfully I never used one of those. lol

[Pvt Parts]

Originally Posted by Ed Wright

But, those were Fords. And sbc = Small Block Chevy, which has a great oiling system, unlike the early Fords. Myself, and many others building small block Chevys use the STD volume pump, modified for LESS volume. I also limit mine to 40 psi @ 8500 RPM. Bearings always look like new. Just replace them when I start to feel guilty about running them so long. If you ever build a sbc, call Larry Stewart Sr about buying an oil pump.

Takes a while for the newbies to catch on Ed. I was doing the same thing to my pumps back in the late 70's and 80's. And we're not talking about changing the bypass spring.

[Ed Wright]

Originally Posted by Pvt Parts

Takes a while for the newbies to catch on Ed. I was doing the same thing to my pumps back in the late 70's and 80's. And we're not talking about changing the bypass spring.

Wish I could think of the guy's name that got me thinking correctly about sbc's oil pumps. He was a Modified & Comp engine builder from New Mexico in the '70s. Wish I could think of his name now. (I’m old) Had the pick up tube fall out of the oil pump in my ’56 Chevy at Albuquerque NM. Too much blowing sand & dirt to pull the pan there! I just loaded up. He was asking what happened, and told me I should be pulling the spring and braze the pick up in place, then ask how much oil pressure I had? I proudly announced “65 psi!” He said, “And a high volume pump?” I said “Yes!” He then screwed my head on straight about pumps and pressure. I have an old rear main cap, tapped for a fitting, flexible hose and oil pressure gauge. I bolt the pump to it, drop in the parts washer and spin it up with a ½” drill. What I see there, I see in the car. Been doing it this way since that day. Before synthetic oil too. <G>

[BlueOval Ralph]

McClintock?

Originally Posted by Ed Wright

Wish I could think of the guy's name that got me thinking correctly about sbc's oil pumps. He was a Modified & Comp engine builder from New Mexico in the '70s. Wish I could think of his name now. (I’m old) Had the pick up tube fall out of the oil pump in my ’56 Chevy at Albuquerque NM. Too much blowing sand & dirt to pull the pan there! I just loaded up. He was asking what happened, and told me I should be pulling the spring and braze the pick up in place, then ask how much oil pressure I had? I proudly announced “65 psi!” He said, “And a high volume pump?” I said “Yes!” He then screwed my head on straight about pumps and pressure. I have an old rear main cap, tapped for a fitting, flexible hose and oil pressure gauge. I bolt the pump to it, drop in the parts washer and spin it up with a ½” drill. What I see there, I see in the car. Been doing it this way since that day. Before synthetic oil too. <G>