Pressure Drop with Remote Oil Filters

Ron Earp

Ron Earp

Administrator
I'm thinking about using a twin remote oil filter mount on the JH to make oil changes easier, increase oil capacity, and lower oil temp. As well as make it easy to plumb in my Accusump.

But, I was wondering - anyone know what the oil pressure drop is got all this plumbing? There is no way in hell there isn't a pressure loss with all of the hose, filters, etc. in the system. Anyone measured it or have some sort of estimate? I'd guess 3-7psi just off the top of my head, but I'm not really sure. Lotus 907s
(and the later engines in the Esprits too) are not known for great oiling and at idle can be hard pressed to produce 10-15 psi - so you can see my concern.
Thanks,
Ron

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Ron Earp
NC Region
Ford Lightning
RF GT40 Replica
White Jensen-Healey ITS
Silver "Skull" 260Z ITS
Email: "rlearp at gt40s.com"
 
Of course you'll lose oil pressure. Why not! Only remote filter worth a damn is the Oberg. And even it will cause the pressure to drop. GRM ran a filter shoot out in the late 80s or early 90s. Wix had the lowest restriction and Fram filtered the most dirt out. Looks like its time for GRM to have a new shoot out. Ever oil enginner I ever talked to, said to stay far away from off the counter dual filters. Y in and Y out is the only way. GET AN OBERG.
 
Just remember that bigger ID oil lines and hose ends between the components will reduce the pressure loss.
 
As was stated, larger lines will reduce the pressure drop. I ran -10 lines on mine. I used a Canton/Meca filter.

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MARRS #25 ITB Rabbit GTI (sold) | MARRS #25 HProd Rabbit
SCCA 279608
 
Seems like I remember in school, that as a pipes id increases, the volume increases, but the pressure decreases, because the pump now has to move more oil. Now most if not all pumps are running against their bypass aren't they? More oil, less pressure. Or like many thing, do I have it backwards? DICK.
 
Ron:

1. The extra oil capacity from bigger/more filters really isn't usable, as it all has to be there to maintain pressure, and the only thing that will significantly decrease oil temperature is a better (bigger cooler and/or more air flow)cooler arrangement.

2. Having said that, the pressure drop (apart from the filters) if the system is plumbed sensibly (radiused fittings, large enough line) will be pretty small, and will be negligible at hot idle due to the thin oil and low flow rate at idle. I did some calcs when replumbing my VW, and the system pressure drop (excluding the oil filter drop) came to only a few psi at full flow ie high rpm. If you get info from Aeroquip you can calculate the losses, but if you use the right parts and something like a -10 line you should be fine. I actually used -8 and all is well, but my engine probably flows less oil than yours.

3. Reading Dick's posts - if the twin filters are plumbed in series, that WILL create a significant extra pressure drop, sounds like a bad idea, I agree. I don't agree that bigger lines will lower the oil pressure though, the oil is primarily metered by the smallish clearances in the bearings, etc AFTER the lines, and the pressure should be measured after the lines as well.

Good Luck,

Al Seim
Action Digital Race Data Systems
 
Addressing only the higher rpm issue, most of our pumps are limited in pressure by a pressure relief valve or pressure bypass. Pressure and volumn are inversely porportional but if you have excess pressure available, the pump will compensate and maintain pressure and volumn. I have used both -10 and -12 lines on my cars, and actually liked the temp/pressure readings on the -12 lines better. Note that any oil coolers you look at by Fluidyne and those types of manufacturere are always -12 fittings.

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Chuck Baader
#36 ITA E30 BMW
Alabama Region Registrar
 
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