Im about to start putting my 350 motor together and keep seeing negative comments on high volume pumps. I bought the speedpro summit piston kit and it comes with a high volume oil pump. Should i not use it? Why would they put it in the kit if it was going to be a negative thing? My motor is a 10:1 fairy stout street motor with the edelbrock rpm heads.

I've used HV pumps and regular pumps and they really haven't made much, if any, difference on street motors. I really think the problem is when you use a hig volume pump with a pan that only holds 5 quarts, then you run the risk of out pumping your oil capacity when you spin high rpms. Are you running a stock pan or a higher capacity pan?

Mike

If the motor sees anything close to 7000, I;d advise against it. Pumps are like $22. For your typical 5500 rpm street motor, it shouldn't make much of a difference. Those who say it doesn't suck a pan dry, never took a 427 with 4.5 qts to 7500 rpm. It does. Not that it was the HV pumps fault. graemlins/clonk.gif

Anyway, it was clear to the machinist that the bearnings showed signs of oil starvation.

Nevertheless, they are a waste of energy, but no matter if your motor won't see high r's.

I'm useing one now. this is the only problem I've encountered....wear on the distributor gear.

http://www.bigblock67chevelle.com/dist.jpg

Yup, takes energy to screw up a gear like that. Waste of energy. You wnat trick? Spend $20 ona std pump, ball mill out some anti-cavitation troughs and make sure you have no more than .002" endplay in the gears. $20, plus 1/2 hour, makes a $65 blueprinted pump. Now that's trick!

If you are running a loose bearing clearance like out on the high end of the tolerance. .0027-.003+,
and high rod side clearance, I think the max rec. is .026ish. Then you may need a HV pump to get the pressure up. If your running the conventional wisdom of low .002 bearing and less than .0018ish on the rod sides, then an HV will probably eat up the cam.
Now if you run a billet timing set, I think they eat the front of the block too with an HV and tight clearances. Since this is expensive stuff to experiment with, this all JIMO. Although I have seen the big clearance HV req. in a SB mopar.

And the HV, high R, small pan phenomenon, BTDT.
" Why does it take 80ftlbs to turn my engine over w/o the plugs in?" Beat that Porche on the freeway though smile.gif

And on the BBC pumps, There are 3. The STD, the L88/ZL1($$), and the HV. The L88 is inbetween the two in size. Cost about $100 when I checked 10 years ago.

Good question.
My opinion is they mainly sell it because people have been brainwashed by all the rags among other places into believing you need a hi volume pump.
You know,, another one of those deal that if it gets written about enough it becomes gospel :D

You don't need one.

Will it "pump the pan dry? Absolutely not. This is not possible as the extra oil it pumps is dumped into the bypass & returned to the inlet side of the pump unless the pump has been modified to return it to the pan which I feel should have been done in the first place.

Will it accelerate drive gear wear?
Probably, especially if you are running excessive pressure.

Will it put more oil through the bearings?
Only if you have too much clearance.
It will put slightly more oil through the bearings but only because of added pressure not volume.
You can do the same thing with a hi pressure std vol pump.

Can it cause a drop in pressure at high rpm?
Yes if the pickup is too close to the pan you can suck a hole in the oil & it can cavitate.
Also there are some including me that believe the return circuit can cause cavitation under certain circumstances at high rpm.
Reasoning,, you are dumping hi pressure oil into the inlet which is a low pressure area & my feeling is you can actually cause a cavitation issue by "blowing" too much hi pressure oil into this circuit.
I could be way off here but have seen pressure drops of 5-10 lbs at high rpm on the dyno for no apparent reason & know the pickup was not the problem & windage shouldn't have been so I feel something was aerating the oil???

There are very valid reasons to use a hi vol pump in some instances but a basically stock engine such as yours is not one unless of course someone put clearances in you can drive a truck through :D

I also feel you should use a hi vol pump in a small block if you are using EDM lifters but you still don't want more than 60-70 lbs max.

This mostly applies to small blocks.
I have never used a hi vol pump on a rat including a 482 I used to run years ago that was shifted at about 8600.
I ran the stock L88 pump which did have slightly longer gears than the stock rat pump.

Mike,thanks for the detailed info..great reading.

So Mike, the oil starvation the machinist mentioned wouldn't have been caused by the HV pump?

His reply was simply, " I wouldn't use one on a big block like this.".

Thanks Chris graemlins/beers.gif

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Originally posted by 427L88:
So Mike, the oil starvation the machinist mentioned wouldn't have been caused by the HV pump?

His reply was simply, " I wouldn't use one on a big block like this.". =


Gene,
I don't understand your question??
If you mean emptying the pan with a hi vol pump, no, at least not in my opinion.
If you mean aeration or cavitation caused by returning too much oil to the inlet or from "sucking a hole in the oil at the pickup from being too close to the pan then yes as once you induce air into the oil, even a little air, it causes real problems.
The air bubbles are not real good at supporting any kind of load & you end up with metal to metal contact even though you are still pumping oil if it has air or foam in it.
It also takes a while to get the air out & during this time you are circulating a very inefficient lubricant.

As I said, I have never used a hi vol pump in a rat.
There are some applications where you need a lot more pressure & some where you may need more volume but I can't think of any we are dealing with here in a rat.

I said I used a stock L88 pump in a 482 about 30 years ago & to calrify, I did shim the relief to 80-90lbs of pressure hot because of the rpm I was running.
L88 pump, factory deep pan & factory pickup.

It was in a Vega back before I "knew better" with a GM crank & 7/16 L88 type rods that was shifted about 8400 three times & went through the lights at about 8600.
32" tires, 5.38 or 5.57 gears & 150+MPH. You do the math!!
I had to put pins like an aluminum rod has to keep the bearings from turning in the rod bores!!
I ran this engine so long it was developing a ridge :D
Point is, stock pumps work pretty good ;)

That hi-volume pump thing is just a bunch of marketing. You have to ask yourself, "what exactly will this engine be able to do with a hv pump that it won't do with a stocker?"

I've run engines with a stock pump for hours at a time 6,000+ rpm WOT. Never had one fail due to a stock pump.

I decieded to take my M55HV out and install a M55 w/ the Mr. Gasket #26 pressure spring. I also ported some of the anti-cavitation troughs and removed some of the flash in the oil passage.
This was done after I had welded the pickup and install the one piece pan gasket. Good thing is these gasket are reusable.

Be sure and measure your gear to cover clearance while you are in there. I bought a pump once that had .006"!!! You want right around .002"

Mike