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

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

Post by Turborick » Wed Oct 25, 2017 9:38 pm

R.Brown wrote:
Wed Oct 25, 2017 1:12 pm
I did not read any responses, but do you have some kind of internal support to the scavenge lines, and the supply line from the tank? Also what size are the lines? I've personally seen things like this happen on the dyno, and have since then never build a dry sump system without using internal support coil on any suction line. Now-a-days there are some places that make vacuum service hoses that do not require the coil installation, a place in NC... name escapes me... ahh, Brown & Miller.

From memory, The vacuum rating on hoses is at ambient temps, and is a whole 'nother story when up to normal oil temps.

Just a thought,
ryan
-12 on the feed line and all suction lines with a flat spring
Rick Yacoucci

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http://www.bonnevillestreamliner.com

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

Post by Turborick » Wed Oct 25, 2017 9:39 pm

leahymtsps wrote:
Wed Oct 25, 2017 7:23 pm
The bottom of the tank and the pump are at the same level
yes there are 2 tube 90's one at the tank and another at the pump. the supply line is -12
oil pan is a Dan Olson right side kickout, scraper, windage tray, #12 pickups, separating diverters, and capturing trough
the pump is a peterson 4 stage. 2 to the pan and one to the valley

Personally I would be using a -16 supply line


Tom
no room at this time for a -16 line
Rick Yacoucci

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

Post by Racerrick » Thu Oct 26, 2017 10:54 am

A spring inside the hose can cause turbulence. I use this hose http://www.bmrs.net/PTFE_hose_01.html rated to 28hg vacuum. I would be trying to get a #16 hose in there anyway I could. Pan pick up cut at 45 degrees?

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

Post by BlackoutSteve » Thu Oct 26, 2017 4:58 pm

This is an approximate, but it shows the oil viscosity of a 30 weight at varying temperatures.
Basically, you want to aim for 10 cSt at your oil's operating temperature, and for typical engine oil temps of around 100C/212F, a 30 weight is the right choice.

However, a 30 weight at your running temp of 135F/57C has about 30 cSt viscosity which is about 3x the viscosity of what you should have.
...and then you're pumping through a lot of hose and spinning this engine to 9500. :shock:

Image
Post pictures, or it didn't happen!

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

Post by cjperformance » Thu Oct 26, 2017 8:27 pm

BlackoutSteve wrote:
Thu Oct 26, 2017 4:58 pm
This is an approximate, but it shows the oil viscosity of a 30 weight at varying temperatures.
Basically, you want to aim for 10 cSt at your oil's operating temperature, and for typical engine oil temps of around 100C/212F, a 30 weight is the right choice.

However, a 30 weight at your running temp of 135F/57C has about 30 cSt viscosity which is about 3x the viscosity of what you should have.
...and then you're pumping through a lot of hose and spinning this engine to 9500. :shock:

Image
I totally agree with selecting viscosity for your oil operating temp , 10cST - but at what clearance? 10cST may be great for .001 to .0015 but not for .0025 - .003"
Craig.

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

Post by BlackoutSteve » Thu Oct 26, 2017 10:39 pm

cjperformance wrote:
Thu Oct 26, 2017 8:27 pm
I totally agree with selecting viscosity for your oil operating temp , 10cST - but at what clearance? 10cST may be great for .001 to .0015 but not for .0025 - .003"
GM have been specifying a 30 weight for at least five decades in their engines with .001" per inch of diameter.
It's totally normal for a 30 weight running at 212F in any engine with that amount of clearance.
Post pictures, or it didn't happen!

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

Post by leahymtsps » Sat Oct 28, 2017 6:43 am

Racerrick wrote:
Thu Oct 26, 2017 10:54 am
A spring inside the hose can cause turbulence. I use this hose http://www.bmrs.net/PTFE_hose_01.html rated to 28hg vacuum. I would be trying to get a #16 hose in there anyway I could. Pan pick up cut at 45 degrees?
The spring also reduces the hose I/d. Hard to imagine there isn't room for a -16 supply line. Olson
makes a very good pan.

Tom

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

Post by cjperformance » Sat Oct 28, 2017 6:54 am

BlackoutSteve wrote:
Thu Oct 26, 2017 10:39 pm
cjperformance wrote:
Thu Oct 26, 2017 8:27 pm
I totally agree with selecting viscosity for your oil operating temp , 10cST - but at what clearance? 10cST may be great for .001 to .0015 but not for .0025 - .003"
GM have been specifying a 30 weight for at least five decades in their engines with .001" per inch of diameter.
It's totally normal for a 30 weight running at 212F in any engine with that amount of clearance.

I'm not really fussed about what GM have specified for 50 yrs. That doesn't really mean much.
Craig.

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

Post by swampbuggy » Sat Oct 28, 2017 8:17 am

Its hard for me to imagine a -12 hose which is .750" i.d. is a restriction for the oil flow with everything else proper.

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

Post by naukkis79 » Sat Oct 28, 2017 9:12 am

Con rod bearings will flow more oil at high rpms if there's not enough flow and they heat up. With too thick oil it's easy to burn them. It's usually not recommended to rev high until oil has warmed up to 80 degree Celsius.

I think that oiling system is fine, warming oil to right operating temperature and oil pressure stays constant, too cold oil results too much oil pressure at low rpm.

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

Post by Newold1 » Sat Oct 28, 2017 10:23 am

His very high oil pressures at lower rpms kind of support that idea also. Look at the printout at what appear to be shift points. My question is there an oil pressure relief in the system or are these oil pressure reading unevenness due to rpms only?

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

Post by gnash » Sat Oct 28, 2017 10:34 am

Sorry if I missed this in previous posts-
I assume oil pressure measurement is by electrical sender/gauge. Is the power to that system well isolated and the signal wire well shielded?

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

Post by Turborick » Sat Oct 28, 2017 11:38 am

Racerrick wrote:
Thu Oct 26, 2017 10:54 am
A spring inside the hose can cause turbulence. I use this hose http://www.bmrs.net/PTFE_hose_01.html rated to 28hg vacuum. I would be trying to get a #16 hose in there anyway I could. Pan pick up cut at 45 degrees?
the OD of that -16 hose is the same as the OD of my -12. I have fittings and hose orded =D>
I will check pickup when I pull the pan
Rick Yacoucci

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http://www.bonnevillestreamliner.com

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

Post by Turborick » Sat Oct 28, 2017 11:54 am

BlackoutSteve wrote:
Thu Oct 26, 2017 4:58 pm
This is an approximate, but it shows the oil viscosity of a 30 weight at varying temperatures.
Basically, you want to aim for 10 cSt at your oil's operating temperature, and for typical engine oil temps of around 100C/212F, a 30 weight is the right choice.

However, a 30 weight at your running temp of 135F/57C has about 30 cSt viscosity which is about 3x the viscosity of what you should have.
...and then you're pumping through a lot of hose and spinning this engine to 9500. :shock:

Image
So what grade oil should I be using? 10 weight?
Rick Yacoucci

Nebulous Theorem III.V
http://www.bonnevillestreamliner.com

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

Post by Turborick » Sat Oct 28, 2017 12:24 pm

I just measured my -12 hose and its .660 id without the spring a about .600 id with the spring
the brown and miller -16 hose I just ordered is .870 id
the area of .600 is .28 and the area of .870 is .59 so I will be doubling the area
the length of the feed line is 6'
XRP hose chart show the -12 would support about 10GPM
and the -16 about 25GPM with similar pressure drops.
I believe my engine with a Large ball bearing turbo and piston squirters should be about 14+...??
what is the max pressure drop I should have?
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.

Image
Rick Yacoucci

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http://www.bonnevillestreamliner.com

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