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  • 2 Post By cycleguy55

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  #1 (permalink)  
Old 07-14-2020, 08:49 PM
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Default Oil pressure

What is 'normal' oil pressure on a stroked 392 Ford Racing motor (430HP). This is the motor on my 2011 build (#983)?
I just changed the oil (9 qts of 10W-30), added two bottles of the zinc additive and using the WIX 51515 filter (5" long filter). While warming up and at idle, the guage was reading 3 1/2 bar (~50 psi). I have seen lower readings at idle after driving the car around for awhile. Just wondering what are the parameters that cause the oil pressure to rise and fall....and what is considered 'normal' at idle and at higher revs.
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Old 07-14-2020, 08:55 PM
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sounds about right my 351 stroked motor runs the same pressure as yours.
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Old 07-15-2020, 05:23 AM
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My Roush 427 running 10w30 is about 3 1/2 bars during warm up but drops to 1 3/4 Bars when fully warm on a hot day at idle, Roush recommends 10w30 as long as PSI remains above 20 at idle.
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Old 07-15-2020, 07:33 AM
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do you have an oil cooler with thermostat ?

Mine is 3.5 bars warming up, thermo closed.
Around 2-bar with the thermo open.
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Old 07-15-2020, 07:41 AM
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Quote:
Originally Posted by SBSerpent View Post
Just wondering what are the parameters that cause the oil pressure to rise and fall....and what is considered 'normal' at idle and at higher revs.
In broad terms:

The maximum pressure is somewhat controlled by the spring in the oil pump. The valve opens when the max pressure is reached, and oil is diverted back to the oil pan. A high pressure pump usually just has a stiffer or shimmed relief spring.

If bearing clearances are tight, pressures tend to be higher. Think of putting your thumb over the end of a garden hose. Bearing clearances tend to increase as the surrounding metal gets hot. When bearing clearances increase, pressure drops a bit.

Higher viscosity oil will increase pressure to a point. Going from 30-40 probably won't change anything. But going from a 30 to a 60 probably would.

The old adage is 15-20 psi at idle, and add 10psi for 1,000 rpm's doesn't really work all that well with modern technology. 15-20 at hot idle is good. But max pressure for most engines should be 45'ish.

It takes energy to create pressure. The more energy you use to spin the motor around, the less energy reaches the tires.

The drive mechanism is off the front of the cam, and through the distributer gear. Work that mechanism too hard and it will eventually break.

There is no need ever for a high pressure pump on a Ford Windsor engine. There's a lot of debate about high volume pumps, though.

You need enough oil viscosity to maintain proper pressure, and no more. If your street engine maintains good pressure with 0W-20 oil, there is no advantage to using 5w-40. Race engines can see improved valve train stability with a 40 oil.
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Old 07-15-2020, 08:49 AM
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No oil cooler.

Does the brand or size of oil filter affect pressure?
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Old 07-15-2020, 09:24 AM
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This is an age old question that has more urban legend and mystery surrounding it than Big Foot does. The phenomena of fluid pressure (including oil pressure) is very old science and actually quite straight forward.

With a known unregulated fluid volume supply (hydraulic pump) and an orifice you can determine the changes in pressure by simply by changing the orifice and / or the volume of the fluid supply.

The pressure rises of falls as the square of the change in orifice diameter. Lets use Bobs garden hose example because it is a very good illustration. If our spigot is capable of delivering, lets say 10 gallons per minute, and we have a nozzle diameter of 1 square unit of area measure (pick your favorite units square millimeters, centimeters, inches etc.) doubling that area will change (in this case reduce) the pressure by a factor of 4 compared to what it originally was.

If we maintain the same fluid flow at the nozzle the pressure at the nozzle will be reduced to 25% of what it originally was. Similarly if we maintain the same fluid pressure at the nozzle the flow will become 4x what it was. So far seems like pretty straight forward common sense other than the math

When we include a pressure relief valve it gives the fluid system designer the ability to tailor the low speed pump delivery or the high speed pump delivery.

Lets say you want to increase low speed oil flow but have a maximum high engine speed flow you do not want to exceed. This is where pump capacity and the pressure relief valve comes into play.

By going to a higher volume pump you will increase oil flow to the engine bearing surfaces at all engine speeds but most importantly at low speed where you were most interested in increasing flow. The rub comes in as engine speed increases.

By doubling the engine speed and therefore the pump speed, you will quadruple your high speed oil pressure. But I only wanted 60 psi oil pressure at 5000 rpm and unregulated the bigger pump will produce over 200 psi at 5000 rpm. This is where the pressure regulator, what we call the pressure relief, comes into play.

By using a pressure regulator with adequate flow capacity to bleed off unneeded volume and setting the opening pressure at 60 psi we can have the increased low speed flow and also limit the 5000 rpm (or wherever you pick) pressure and flow to our preferred 60 psi target.

That's it in a nut shell. This is an excellent 2 minute video from Melling where George Richmond shows the effect of changing nozzle size by changing bearing clearances. Click here => Melling Video

If you are using an OHC engine (like I do) something you need to be aware of is that your cams are at the end of the oiling food chain and get oiled last. Because an oil system is a controlled leak. Putting additional clearance at the rods and mains will take oil away from the cams and put you as risk of seizing a cam in the head, breaking your timing chains and using up a lot of expensive parts.

Even if you have an OHV engine design you still have to oil the heads for rocker trunions and valve spring cooling. If you reduce the oil to the heads you are cheating the rockers, pushrods and springs. At some point in time, probably sooner rather than later, you will have to pay the piper — and it won't be cheap.



Quote:
Originally Posted by SBSerpent View Post
What is 'normal' oil pressure on a stroked 392 Ford Racing motor (430HP). This is the motor on my 2011 build (#983)?
Stroker cranks do not change the engine's oil appetite, it remains the same as the stock stroke version of the engine.



Quote:
Originally Posted by SBSerpent View Post
I just changed the oil (9 qts of 10W-30), added two bottles of the zinc additive and using the WIX 51515 filter (5" long filter). While warming up and at idle, the guage was reading 3 1/2 bar (~50 psi).
Warm up pressure and operating pressures will always be different. The important pressure you want to pay attention to is your fully warmed up temperature and as Bob already stated heavier weight (higher viscosity) oils will produce slightly higher oil pressures.



Quote:
Originally Posted by SBSerpent View Post
I have seen lower readings at idle after driving the car around for awhile. Just wondering what are the parameters that cause the oil pressure to rise and fall....and what is considered 'normal' at idle and at higher revs.
As oil temperature comes up to engine operating temperature oil viscosity will decrease. Absent changes in volume, increased temperature reduces viscosity and at constant volume it will also reduce oil pressure.



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Last edited by eschaider; 07-15-2020 at 11:45 AM.. Reason: Spelling & Grammar
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Old 07-15-2020, 10:41 AM
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Quote:
Originally Posted by SBSerpent View Post
No oil cooler.

Does the brand or size of oil filter affect pressure?
Yes. In a Windsor engine, the oil goes from the pump directly to the filter. The stock oil pressure sender is after that.

A cheap (Fram), clogged, or too small filter can be restrictive. The pump is pushing against the restriction, and that increases the pressure enough to open the relief valve. Everything after the filter then has a lower pressure, and a lower flow.

I prefer either the Motorcraft FL1-A or a Purolater Pro-1 filters.
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Old 07-15-2020, 10:51 AM
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That being said, is it best to always go with a longer (higher capacity) filter than a shorter (lower capacity) filter?
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Old 07-15-2020, 12:54 PM
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Quote:
Originally Posted by SBSerpent View Post
That being said, is it best to always go with a longer (higher capacity) filter than a shorter (lower capacity) filter?
A higher capacity filter is capable of filtering more contaminants before its internal pressure relief valve opens and oil bypasses the filtering media. So, yes, generally a longer filter is preferred to a shorter filter - all else being equal.

BTW, Wix 51515 is a good filter, equivalent to Motorcraft FL-1A IMO.
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Old 07-15-2020, 02:05 PM
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Yes, the 51515 is what I am using. I had swapped out to the WIX 51068, which is almost an inch shorter in length but then figured I didn't need to because the 51515 fits between the motor and frame no problem.
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Old 07-15-2020, 02:46 PM
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If you're worried about low oil pressure then you should buy an FE. With FEs, there's no such thing as low oil pressure. See: Oil Temp 265 Degrees and Pressure Only 9 PSI -- Did Ford Say That Was OK for a 427?
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Old 07-15-2020, 04:15 PM
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Quote:
Originally Posted by bobcowan View Post
Yes. In a Windsor engine, the oil goes from the pump directly to the filter. The stock oil pressure sender is after that.

A cheap (Fram), clogged, or too small filter can be restrictive. The pump is pushing against the restriction, and that increases the pressure enough to open the relief valve. Everything after the filter then has a lower pressure, and a lower flow.

I prefer either the Motorcraft FL1-A or a Purolater Pro-1 filters.
I installed an Oberg oil filter setup on my Roush 427. Better flow increased pressure and is cleanable. These are the same filters used on NASCAR machines , NHRA fuel dragsters. More expensive but they are reusable as long as you own the engine. Check it out a Oberg Industries
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Old 07-15-2020, 04:18 PM
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Quote:
Originally Posted by Lou1119 View Post


I installed an Oberg oil filter setup on my Roush 427. Better flow increased pressure and is cleanable. These are the same filters used on NASCAR machines , NHRA fuel dragsters. More expensive but they are reusable as long as you own the engine. Check it out a Oberg Industries
It is not Oberg industries. Look up Oberg oil filters.
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Old 07-18-2020, 09:09 AM
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Oberg Filters has been manufacturing eco-friendly filters, filter accessories and race parts in Washington State since the early 80’s. Originally designed for auto racing, our filters exceptional filtering and diagnostic capabilities were quickly recognized and are now used in many applications including: marine, agriculture and industrial.

https://www.obergfilters.com/
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