when is a good time to get aHV oil pump?

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DusterBoy15

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when should a HV oil pump be needed? high reving cars or any car thats making 400 flywheel hp?
 
I've always used a HV oil pump in any high performace engines.
 
I would poise this question to the tech guys at whoever's pump you are thinking about using. I am sure they will ask you all the right questions in order to tell you what you should be running and the pros/cons.
 
Just throw in one of those high pressure springs in your stock pump to bump up your oil pressure a bit.
Summit has them DCC-3690944 for $5.25
 
the stock pump is good, most people think that high volume is neccesary but i've used the stock pump on my last stroker 408 and it was more than adequate. That motor put 330 hp to the wheels.
 
just don't fall under the asumption that because you use a stock oil pump you don't need a high volume pan. the more rpm's the less oil in the pan and of coarse the less money in your wallet.
 
You dont need it unless you clearances are way off. Regardless of HP or pan. It's just a crutch that generates heat most of the time. Get the clearances and machining right, and it's not needed at all.
 
ok so stock it is. also what clearances??? like for what parts? my mak rpm is 6000 so i need 60 plus psi
 
If you use an oil with a little viscosity, say 20w50 or so a standard oil pump will give you at least 60psi at 6000. If it doesn't, get the spring it only takes 5 minutes to change in the car.
 
I'm with Moper...not needed if the motor is built right. HV pumps even suck power out of the engine.
 
I also agree with Moper, you really only need one when the rod & main clearances are too "loose". I only use stock pumps, including my drag car.


Chuck
 
As long as your main and rod clearances are within factory specs, you'll be fine with the stock pump. I'd shoot for the loose side of the factory specs, but don't go nuts. .002 is a reasonable target, and you should get 65 psi out of the stock pump, albeit with a shimmed or high pressure spring.

A bigger pump will not give you more pressure any more than a high pressure relief spring will give more volume. High pressure will suck more power than high volume, but both will place undue loads on the engine internals. Think about the load path of the power to drive the pump... From the crank through the timing chain, end-to-end down the cam (which will twist just like your torsion bars retarding valve timing on rear cylinders slightly) through the intermediate shaft and finally to the pump. Higher drive forces mean higher friction, and these loads increase at the square of RPM. Similar effect to running too much valve spring, horsepower wasted due to internal friction.

So, how to tell if your oil pump is adequate? First Mopar small block oil systems are pretty good, but there is a simple experiment to illustrate how good one is working. Put the trans in 2nd and slowly accelerate from 1500-4500 RPM or so, watching the oil pressure gauge. The oil pressure will climb with engine speed for a while and then level off, climbing no higher. This level off is the point where your bypass opens. At this point your pump is delivering more volume than the engine can handle, and excess oil just goes back to the pan. A bigger pump would do little, other than cause the bypass to open at a lower RPM. Typically by 3000 RPM you will have 45-50 PSI, but each combo will be a little different. If the pressure levels off, but begins climbing again at a significantly higher RPM, then the pump volume is overwhelming the capacity of the bypass. If pressure levels off and then drops at high RPM, your rod bearing clearance is excessive and all the pump in the world will not save your engine from blowing up. Now, if you want more pressure (the 10 PSI per 1000 RPM is a good guideline, but don't lose sleep over being a bit under) use a stiffer bypass spring. This will allow the engine to develop more pressure as RPM rises until again the pump delivers more oil than the engine needs and the bypass opens. Pressure is a good way to visualize how well the oil system is working, but more isn't always better. Sure 60 PSI might make things last longer at 6000 RPM than 30 PSI, but this does not mean that 60 PSI will make an engine last longer at 3000 RPM than 30 PSI. Developing more pressure than you need wastes energy and causes undue wear.

As to the theory that thicker oil will boost pressure, this is misguided. Thicker oil makes more pressure because of it's resistance to flow (definition of viscosity). So the pump will overwhelm the bypass and pressure will rise. The bypass always opens at the same pressure. This is why a cold engine will show higher pressure. But the same resistance to flow means the oil may not be getting everywhere it needs to go. Remember that your pressure gauge takes it's signal pretty far upstream in the system. Thick oil is a crutch, but no substitute for proper clearances. Mopar small blocks live long lives on 10w30 at 45-60 PSI. The bottom ends of these engines didn't change much over 40+ years of production because it was a good design to begin with. Why reinvent the wheel?
 
I once used HV pumps or a heavier/shimmed spring on most of my cars since the old Direct Connection books recommended it, but they always seem to cause leaks in my engines, especially at the rear main seals on the big blocks. After talking to a lot of machinist the consensus was they`re not necessary so now I don`t use them. I agree with most of the field that they`re generally not needed.
 
C130 Cheif , that is alot of good information! I agree with every bit of it from what I have seen and worked with. But I liked how you explain oil pressure relative to problems in the engine, that was fantastic. But like a friend of mine said, you need a good solid foundation for a house, you need good solid machining for an engine.
 
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