OIL PRESURE

[rich2481]

I have two cars with mellings and never had any trouble with stock springs, but i make sure my plungers are not stuck

[Pablo]

Me too, Rich. After fiddling for years with stronger springs, bigger pumps, etc, I find that a new dual relief case with stock springs and a stock or slightly oversized pump works fine. Blown filters almost always indicate a sticky relief valve, and sometimes a pump size or spring pressure that is way overboard.

Paul

[74baja1915]

i have a stock case as-41 with the dual relief and stock springs. sothe melling 30mm is going to be a bad combo. i should switch to a smaller pump and stay stock

------------------
If its not broke don't fix it, but if it can be made better by all means do it!

[74baja1915]

well i picked up the motor today and i ask the builder what he recomended for oil and he told me to use nothing but 20w-50 when i told him i thought that might make too much oil pressure he looked at me like i was crazy. hes been building them for a while and everyone i see there i ask about his work and know one can say anything bad. just thought i would throught that out there

------------------
If its not broke don't fix it, but if it can be made better by all means do it!

[rich2481]

I used the melling in my stock 1600 and another in my 1835 rail engine, the melling is about a 1/4 inch thicker and never had any trouble with it at all with over pressure.

[Locash Mike]

A Berg pressure relief cover would be good insurance if you're running a full flow setup.

------------------
Locash Mike
www.locashracing.org

[david58]

[FJCamper]

A word of advice relating to oil pressure is the condition of your lifter holes.

Years ago (but not so much now) there was a practice to machine off or into the lifter bore to allow more lifter travel from super-high-lift cams. I have an aluminum "race-case" with the lifter-bores cut down.

This can cause enough oil pressure leakage around the lifters to seriously drop oil pressure to 5psi at low RPM with hot oil, and by hot I mean racing hot ... 240-260 F. or more.

I currently have a Melling cast iron pump in that case to compensate, using standard relief springs. There is a lot of oil volume for the Melling to move. Our system holds eight qts, with AN-8 lines running inside the Ghia feeding a HP-1 filter and large cooler.

You want to run the lightest oil you can and still get good pressure.

Like everybody else, we ran heavy oil to compensate for low pressure, the heaviest being Valvoline 20-50. Great oil, but 50w is too much to pump when you realize what kind of HP it takes to turn that pump.

Also, VW case oil galleries are not large enough for 50w. Sit down with some aircraft mechanic people one day and talk oil passages in their air-cooled four and six cylinder engines. Much bigger.

The VW oil viscosity sweet spot seems to max out at 40w for hot weather or racing.

[farmer]

A word of advice relating to oil pressure is the condition of your lifter holes.

Years ago (but not so much now) there was a practice to machine off or into the lifter bore to allow more lifter travel from super-high-lift cams. I have an aluminum "race-case" with the lifter-bores cut down.

This can cause enough oil pressure leakage around the lifters to seriously drop oil pressure to 5psi at low RPM with hot oil, and by hot I mean racing hot ... 240-260 F. or more.

I currently have a Melling cast iron pump in that case to compensate, using standard relief springs. There is a lot of oil volume for the Melling to move. Our system holds eight qts, with AN-8 lines running inside the Ghia feeding a HP-1 filter and large cooler.

You want to run the lightest oil you can and still get good pressure.

Like everybody else, we ran heavy oil to compensate for low pressure, the heaviest being Valvoline 20-50. Great oil, but 50w is too much to pump when you realize what kind of HP it takes to turn that pump.

Also, VW case oil galleries are not large enough for 50w. Sit down with some aircraft mechanic people one day and talk oil passages in their air-cooled four and six cylinder engines. Much bigger.

The VW oil viscosity sweet spot seems to max out at 40w for hot weather or racing.

Agree on the viskosity
Also, ambient temps and tolerances has a lot to dowith what can and should be used.
Around here I never use anything "thicker" than 15w/40 in street cars. (Racing has different parameters) But temps are also at least 10 degree C. colder average than CA. I also hardly ever use large pumps, unless the car has a front mounted oil cooler. I then use the Shadek 30 mm.
I never use the cast iron Melling pump. I feel that the expansion rate cast iron versus magnesium varies too much and have a tendency to cause pressure loss, + they wear out too fast.
The issue with high viskosity oil, high pressure and powerlosses is a highly overlooked and ununderstood problem. (I dont get all of it either) But I feel that it is better to improove the lubrication of the parts inside, - with a reasonable pressure, than go high pressure to cover up some other issues.
On higher reving engines there can easily be found 3-5 hp in regulating the oilpressure to the "correct" level, what ever that is. (I write this way because opinions vary on the matter) I have seen this relation several times, when we dyno both mild and wild engines.
The last one was a 101 hp 2,0 type 4, which had a 30 mm pump installed and stck springs etc. I meant it had too much oil capacity, which was not needed. So I swopped to a 26 mm blueprinted pump and lowered the pressure to what I thought was enough and safe. - Result : + 3,5 hp @ 5100 rpm. Now, the pump naturally does not drag that much, but the excessive oil mist inside the case does.

And on a side note. FJC, your choice of location and type of oil coolers in your Pan America car was one of the few things I did not understand why you did. But thats a whole different discussion, which we better not take here
T