Vacuum pump and maximum "safe" vacuum
 

I dynoed a non marine bbc yesterday, first we dynoed it muffled at 865 hp w carb, then installed customers holley terminator, coil near plug, 4500 tb, 100 lb injectors. Got it to about 900 hp with efi and once we took mufflers off. Has a moroso vacuum pump, we left belt off until end, I didn't expect alot with standard tension rings but surprisingly we gained 17 more hp on top at about 10-12" of crankcase vacuum. Before I rebuilt this, customer bought it fresh and turned bearings to copper in one weekend with vacuum.pump cranked wide open. At that point, it crushed oil filter inward like a pop can that was crunched up. Who's actually ran one, what's a "safe" vacuum.number with nothing extra special done to acct for vacuum pump?

we waited to very end to put the belt on

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idk what I did to pic

I run a gz vac pump on my street car. Very happy with it so far.

There is a lot of information(some bad) on how much you can run.

I was told 12"-15" max. I set mine to 12". So far so good. There is a point of diminishing returns. I just had my car at the dyno this past weekend and my pump was pulling 9-10" at max rpm/ boost. I might have to tweak the relief valve.

Some will say to much vacuum and it will pull oil off the piston pins.

Some will say you will see a drop in oil pressure because the pump is in a vac. I did not see any drop in oil pressure at all.

From what I heard about the Moroso and most vac pumps, you have to spray carb cleaner in there before start up to keep the vanes from sticking. My gz pump does not need that.
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12" was always the magic number on dry sump oil systems in the race cars.

If your just racing it you can 10-15 no issues. If it's gonna be ran for long duration keep it around 10 max. 7 is safer. Gotta say I've never seen an oil filter crumple. Biggest issue with running them long duration seems to be the wrist pins dry out and top ring wear. Being in a vacuum the oil drops back to the pan very efficiently and there is next to zero oil mist that would otherwise be there. Crank seals don't last as long either.
As for the bearing issues he had previously, I doubt that had anything to do with the vac pump.

Yep, IDK what happened to it exactly before it came thru my shop door, when they pulled it out of their mud truck, the oil filter can was collapsed in every direction, they said that was new before their runs where it lost power and oil pressure. Was at 4.600 bore, piston skirts were collapsed .010 to .015, it had a dominator on it that had came off a mega truck (reverse mounted engine) AND they never looked in it and saw it had jet extensions in the front bowl, pistons were white on top, every rod bearing was collapsed but not spun, mains were scorched, wrist pins were galled and it had a broken valve spring. there was still writing on top of the pistons from when it was balanced. When I put belt on vacuum pump and fired it briefly, my gauge hit 20" and shut it off, adjusted the vacuum regulator to about 8 at idle. he took filter with him , ill see if I can get a pic, never seen nothing like it in my life.

We ran a gz pump on a 540 years back. 5-7 for street use, 12-15 for the track. Never had oil related issues with that engine.

I’ve collapsed a few filters with jaw and/or band type filter wrenches trying to take off filters some knumb nutz installed way too tight. :) :wink You know, when you should have stuck a big flat screwdriver thru it 15 minutes before hand. Lol.

i can’t see any either way a filter would crush in. It’s not from a vacuum pump. Oil psi inside at 50psi -100psi. Maybe vacuum of -150 psi ? Don’t think so.


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Glad to see you got it running with the Holley Terminator. Nice numbers!