Oil pressure drops at hi RPM.....Stumped

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Racerrick
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Racerrick » Sat Oct 28, 2017 2:38 pm

some have expressed concern that my oil pressure is to high, is there a problem with running 100psi of oil pressure?
this is a race engine that lives it life full throttle for up to 90 seconds at a time. my thought is more pressure more flow, more flow more cooling.


HP is being wasted. Oil is being heated and foamed unnecessarily. You need flow not excessive pressure. As your chart shows opening up the flow paths= reduced friction. That is FREE hp. You want the lowest pressure the motor will live with and a pump speed and size that produces an idle pressure of 15-20 and 70 max measure at the last bearing, IMHO anymore is a waste of hp. Where are you feeding the oil in into the motor? front or back? front feed gives a less restricted path. opening up the galleys helps.

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Re: Oil pressure drops at hi RPM.....Stumped

Post by Turborick » Sat Oct 28, 2017 3:07 pm

Racerrick wrote:
Sat Oct 28, 2017 2:38 pm
some have expressed concern that my oil pressure is to high, is there a problem with running 100psi of oil pressure?
this is a race engine that lives it life full throttle for up to 90 seconds at a time. my thought is more pressure more flow, more flow more cooling.


HP is being wasted. Oil is being heated and foamed unnecessarily. You need flow not excessive pressure. As your chart shows opening up the flow paths= reduced friction. That is FREE hp. You want the lowest pressure the motor will live with and a pump speed and size that produces an idle pressure of 15-20 and 70 max measure at the last bearing, IMHO anymore is a waste of hp. Where are you feeding the oil in into the motor? front or back? front feed gives a less restricted path. opening up the galleys helps.
At this point in time I'm more interested in durability than HP. Bow Tie block and were feeding both front and back of the block
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Re: Oil pressure drops at hi RPM.....Stumped

Post by MadBill » Sat Oct 28, 2017 3:20 pm

I suppose at the speeds you're running it must take close to 20 HP to pick up 1 MPH? :shock:
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Turborick » Sat Oct 28, 2017 3:48 pm

MadBill wrote:
Sat Oct 28, 2017 3:20 pm
I suppose at the speeds you're running it must take close to 20 HP to pick up 1 MPH? :shock:
LOL not quite about 9HP at 263mph
I guess my point is we are only running 16 psi of boost right now and we should be able to go up to 35 in the future but were making baby steps, to many new systems on the car, some things are acting like we anticipated some are not.
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Warp Speed » Sat Oct 28, 2017 3:55 pm

If you are indeed flowing 14gpm (with what I know about your combo it wouldn't surprise me, especially at 100psi) the -16 feed line will Definitely help things.
As mentioned, you could probably lower the op to 70-80, but with the extended duty cycle and your power levels, risk vs reward isn't there to go any lower IMO.
On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!

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Re: Oil pressure drops at hi RPM.....Stumped

Post by MadBill » Sat Oct 28, 2017 4:06 pm

Warp Speed wrote:
Sat Oct 28, 2017 3:55 pm
..On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!
Especially if you're running pan vacuum and presently pulling less than say 8"Hg.
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Turborick » Sat Oct 28, 2017 4:27 pm

Warp Speed wrote:
Sat Oct 28, 2017 3:55 pm
If you are indeed flowing 14gpm (with what I know about your combo it wouldn't surprise me, especially at 100psi) the -16 feed line will Definitely help things.
As mentioned, you could probably lower the op to 70-80, but with the extended duty cycle and your power levels, risk vs reward isn't there to go any lower IMO.
On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!
Can you explain how more stages can help with Aeriation? with the current pump I am seeing 20 kpa of crankcase vacuum at full throttle in high gear
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Turborick » Sat Oct 28, 2017 4:31 pm

MadBill wrote:
Sat Oct 28, 2017 4:06 pm
Warp Speed wrote:
Sat Oct 28, 2017 3:55 pm
..On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!
Especially if you're running pan vacuum and presently pulling less than say 8"Hg.
I'm pulling 20 kpa so about 6"Hg ?
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Re: Oil pressure drops at hi RPM.....Stumped

Post by MadBill » Sat Oct 28, 2017 4:48 pm

Turborick wrote:
Sat Oct 28, 2017 4:27 pm
...I am seeing 20 kpa of crankcase vacuum at full throttle in high gear
I forgot your engine is boosted. It's way harder to maintain a vacuum then (anybody?) In NA apps, Joe Sherman has reported as much as a 50 HP gain going from zero to 15"Hg. (~ 50 kpa) vacuum, using appropriate rings. Two more stages will certainly pull more and help with windage, but perhaps not ring seal.
BTW, don't know if it's common practice, but we monitor leakdown time after shut-down as an indicator of ring seal, etc. Our 380" SBF road racer with a 4 stage Aviaid pulled 20" when new and took almost 2 min. to bleed down to 5. When it suddenly began to drop like a rock, we found a leaky intake gasket. #-o
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Mark O'Neal » Sun Oct 29, 2017 3:40 am

If it was a FE I'd look for a block cracked along the oil gallery.

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Re: Oil pressure drops at hi RPM.....Stumped

Post by MadBill » Sun Oct 29, 2017 8:36 am

Correction: It's 5 stage.
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Re: Oil pressure drops at hi RPM.....Stumped

Post by Warp Speed » Sun Oct 29, 2017 8:54 am

Turborick wrote:
Sat Oct 28, 2017 4:27 pm
Warp Speed wrote:
Sat Oct 28, 2017 3:55 pm
If you are indeed flowing 14gpm (with what I know about your combo it wouldn't surprise me, especially at 100psi) the -16 feed line will Definitely help things.
As mentioned, you could probably lower the op to 70-80, but with the extended duty cycle and your power levels, risk vs reward isn't there to go any lower IMO.
On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!
Can you explain how more stages can help with Aeriation? with the current pump I am seeing 20 kpa of crankcase vacuum at full throttle in high gear
By properly evacuating the pan/crankcase.

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Re: Oil pressure drops at hi RPM.....Stumped

Post by stealth » Sun Oct 29, 2017 12:33 pm

cjperformance wrote:
Wed Oct 25, 2017 6:15 am
How well is your oil deairated? I have had to chase a similar problem but in a shorter term rpm combo BUT in a wet sump. A long length of high pressure clear tube in this instance showed the problem instantly. This was in a ford clevelend and was already using an external main feed line, substituting this for clear hose looped past a video camera showed it up.

Agreed!
No doubt I would start here...
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Re: Oil pressure drops at hi RPM.....Stumped

Post by MadBill » Sun Oct 29, 2017 12:57 pm

Warp Speed wrote:
Sun Oct 29, 2017 8:54 am
Turborick wrote:
Sat Oct 28, 2017 4:27 pm
Warp Speed wrote:
Sat Oct 28, 2017 3:55 pm
If you are indeed flowing 14gpm (with what I know about your combo it wouldn't surprise me, especially at 100psi) the -16 feed line will Definitely help things.
As mentioned, you could probably lower the op to 70-80, but with the extended duty cycle and your power levels, risk vs reward isn't there to go any lower IMO.
On another note, if you are flowing 14gpm through that thing, that 4 stage pump isn't helping, especially in the aeriation dept. 6 stage, with 4 in the pan will be waaaaay better if real estate is available, for both performance and longevity!
Can you explain how more stages can help with Aeriation? with the current pump I am seeing 20 kpa of crankcase vacuum at full throttle in high gear
By properly evacuating the pan/crankcase.
On first thought, it might be assumed that more stages and pan vacuum would result in a higher % aeration, but unless external leakage is an issue, there will be no more air mass, possibly even less, if ring seal improves.
Felix, qui potuit rerum cognscere causas.

Happy is he who can discover the cause of things.

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Re: Oil pressure drops at hi RPM.....Stumped

Post by pamotorman » Sun Oct 29, 2017 1:34 pm

I wonder if putting breathers connected directly the oil pan would help so the pressure does not have to go back thru the whole engine and oil to get out ??

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