Lost a Motor last night.

Originally Posted by JN-Motorsports

I know what works for us and we run some 650hp 408 clevelands at 8500 rpm every pass.

Jeff

Same here. Except I don't have any clevelands...only windsors with their "over size" 3" mains. And I've never had a pin or gear failure that was not my fault and I swear by HV pumps. The key is to get the oil HOT before beating on it and don't use heavy oil. You don't need heavy weight oil. Right now I have 0w20 in mine (mobil 1) and it's 90+ degrees on race day with oil temps not dropping below 200 deg from burnout to stripe. Been like that for the last 10-12 years more or less. Only failures I've had were broken blocks and broken cranks. Funny thing about those, every bearing in the engine looked excellent with the exception of maybe a little bit of cast iron that gets into the pump after something breaks (obviously). Never once a bearing issue. I don't run 100 psi either. Don't need to. 65 is plenty for a drag motor, which, oddly enough, is exactly what the Melling M83HV is set at from the factory. You can turn it up a little by driving the freeze plug in a little on the pump but it's not really necessary.

I like lots of oil. Keeps the springs, bearings, and lifters cool but like I said, you can't beat on a cold engine with a HV pump.

With a high volume pump, anything that doesn't go through the engine just gets bypassed. It only gives the engine what it needs.

The bypass spring determines max pressure on any pump. Anything else gets bypassed. If clearances are loose and the oil his hot/thin, the engine might require a large volume of oil before max pressure is reached. The high volume pump simply has a better capacity to reach that limit.

It won't pump any more oil into the galleries than a stock pump will... unless the pressure falls below where the spring is rated... and then it's only pumping more than the stocker because the stocker just isn't keeping up with demand.

If you are racing where that last 2-3hp is of utmost importance, and you want to gamble a little oil volume/pressure for a small power increment, then use the standard volume pump. But, the high volume pump will not hurt anything. High PRESSURE pumps with the stiff springs controlling the bypass are what build a lot of pressure, and cause the extra stress on the distributor gear/pin/shaft.

Originally Posted by JN-Motorsports

Well, I hate to say this. but I beg to differ. H/V oil pumps have a larger (taller) gear set than a stock pump there for more contact surface which mean more drag requiring more effort to turn the gear. You can feel this if you have ever primed a engine by hand. Then place a 100lb spring on a H/V pump and hand prime an engine and you'll go holy cow!
If your in a habit of blueprinting an engine then your oil clearances will be fine for a stock pump with a higher pressure spring. I have had experiences at high rpm with a 25% increase volume H/P pump bending the spring pin on the distributor gear changing my timing by 15 degrees..
To each thier own.. I know what works for us and we run some 650hp 408 clevelands at 8500 rpm every pass.

Jeff

A spring is a spring, and if you put a 100lb spring in any pump it will tear your arm off.

Years ago I did a lot of boat engines, I didnt want to keep guessing where my pump springs were so I made a jig for presetting them. The jig had a mount for the pump and a gauge. I would submerse the pickup into a bucket of oil, the discharge was restricted with a valve and returned the oil back to the bucket. Then I spun the pump with a 1/2 drill.

I had a customer that was determined to run a standard pump with loose bearing tolerence because he was also told that the extra drag from a HV pump would tear up his bronze gears.

To prove my point to this customer, I strapped a inch pound torque wrench to the drill and braced the handle against a post. I preset both a HV and a standard pump to 65lbs and spun each of them. They read exactly the same on the torque wrench. Needless to say, I installed a HV pump in that engine.

Rick

Here's what Melling has to say about high volume oil pumps. (they make both kinds)

http://data.melling.com/Tech%20pdfs/HIGHVOLUMEPUMPS.pdf

I still like to use high capacity oil pans with any oil pump if high rpm is going to be sustained for a very long time. (especially in an engine that tends to flood the top end with oil with marginal drainback) 332-428 FE Fords

Good Luck!