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vacuum pump - when is it needed?

Posted By: 69dart

vacuum pump - when is it needed? - 11/20/14 02:02 AM

I've grown a bit bored already this winter and was researching vacuum pumps. I don't think I've seen too many Mopars around here running them but everything I've read says they helps with power, consistency and generally help keep things sealed up tight. So I was contemplating adding one over the winter. The car is fairly consistent but could always be better.

What do you guys think is the best kit for a BB Mopar?

I'd prefer to run the vacuum pump off the same pulley as the alternator so I only have to run one belt.

My setup is pretty mild - 383 pushing roughly 425HP running 9.80's @ 2100lbs.

Thanks Guys!!
Posted By: OUTLAWSSAA

Re: vacuum pump - when is it needed? - 11/20/14 03:50 AM

Its not possible to run off the same belt as the alternator.Alternator is 2:1 ratio and the vacuume pump is around 1:2. I wish I had a better picture. The vacuum pump is run off a mandrel and the alternator is run off the aluminum pulley.

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Posted By: dvw

Re: vacuum pump - when is it needed? - 11/20/14 05:40 AM

My bet at your level it doesn't need it. Stop any oil leaks,helps power when ring tension is light. I like the GZ kit. Reasonably priced,holds good vacuum.
www.gzmotorsports.com/
Doug

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Posted By: dvw

Re: vacuum pump - when is it needed? - 11/20/14 05:41 AM

Plumbing

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Posted By: Ari440

Re: vacuum pump - when is it needed? - 11/20/14 06:31 AM

moroso 3 vane pump and mandrel


Posted By: an8sec70cuda

Re: vacuum pump - when is it needed? - 11/20/14 03:43 PM

69dart...On your combo, it's wasted money. A race only long stroke and/or high rpm engine w/ low tension rings can benfit from one. I say race only b/c they are a PITA on a street driven car.

If you do decide to get one for some reason, stay away from the Aerospace Components pumps and mandrels.
Posted By: Kam*Kuda

Re: vacuum pump - when is it needed? - 11/20/14 05:34 PM

DVW your setup is so Clean!!!
Posted By: Joes66dart

Re: vacuum pump - when is it needed? - 11/20/14 08:12 PM

We run the aerospace pump and mandrel and have never had a problem with it. Usually pulls 13-15 inches of vacuum going thru the lights.
Posted By: JACK1440

Re: vacuum pump - when is it needed? - 11/20/14 11:10 PM

I was thinking of going to a pump myself. At the end of the season this year I ran into a situation where my standard evac system (header Type) is sucking oil into one of the collectors around mid-track and causing one hell of a smoke screen. Not sure weather to just replace with new or go to a pump.
Posted By: Bigcube

Re: vacuum pump - when is it needed? - 11/21/14 03:52 AM

Header evac systems will smoke bad if you run mufflers. They do not work if there is back pressure in the exhaust. Had the same issue with mine.

I run a Moroso 4 vane pump. It was proven to be worth 25-30 HP with my combo. It would pull about 2 oz of oil on every run. Not something you would want to use on the street.
Posted By: 69pwgt

Re: vacuum pump - when is it needed? - 11/21/14 06:03 AM

i'm looking to put one on my mostly street car (leaks from rear main). Why are you saying they are no good on the street?
Posted By: weedburner

Re: vacuum pump - when is it needed? - 11/21/14 07:33 AM

Just use one of the oem electric vac pumps. They will pull as much as a header evac, and no more leaks. Here's a link to a page with pics/info on the pumps..
Electric evac pump install
Posted By: an8sec70cuda

Re: vacuum pump - when is it needed? - 11/21/14 03:31 PM

Quote:

i'm looking to put one on my mostly street car (leaks from rear main). Why are you saying they are no good on the street?


My suggestion is replace your rear main seal or find out why it's leaking. I'd never install an $800+ kit to stop an oil leak. You need the motor sealed up good anyway so the pump can draw vacuum. Unless your engine is a pretty nasty piece and really needs to vent better.

Vacuum pumps aren't designed for continuous duty (like street driving)....they don't pull enough oil through them at low RPM to lube the pump good and wear out fast. You can add a little oil to the pump before you go for a drive, but that doesn't last long.

GZ makes a pump that recirculates the oil from the catch can through the pump to help w/ street driving...they are the only ones that do this that I know of.

FWIW...I'll never run a vacuum pump again on anything that sees the street. A pair of big lines from each valve cover to a breather tank works just fine.
Pulling 8-10" of vacuum (all my Aerospace pumps ever get) made zero difference in how my car ran...w/ a 572" hemi that has low tension rings. Maybe it isn't enough vacuum, probably should have bought a different pump, etc. My best ET was w/ just a pair of breathers on the valve covers.
Maybe it would make more of a difference w/ a better pump pulling more vacuum, but I have my doubts. My motor is far from a radical race engine though. It makes a little over 800 hp N/A on pump gas.
Posted By: AndyF

Re: vacuum pump - when is it needed? - 11/21/14 07:09 PM

The engine has to be sealed up tight for a vacuum pump to really work. It takes some dedicated machine work to get an engine sealed up that tight. You also need to use the correct gaskets everywhere. If you have an air leak into the engine then the vacuum pump will just make a mess.

If you're thinking of getting a vacuum pump the first thing to try is to pressurize your crankcase and see how long it takes to leak down. Just put about 5 or 10 psi of air into the engine and listen for the leaks. If the engine can hold the air pressure for a little while then it is sealed well enough to run a vacuum pump. If the air blows right out then a vacuum pump probably isn't going to work for you.
Posted By: Cab_Burge

Re: vacuum pump - when is it needed? - 11/21/14 10:06 PM

Back when the vacume pump systems where being introduced into drag racing most of the dyno tests done on a A,B,A test basis found that most vacume pump system didn't gain any measureable HP below 6000 RPM, this was on both BB and SB Chevy motors of course. The higher the RPM tested the more HP gained I have a 3 vane Moroso vacume pump that I am planning on using on my next BB Mopar all out stroker, 555 C.I. , bracket race motor build I'm shooting for 15 to 17 inches vacume at the upper RPM, above 6000 RPM probally, shifting at or above 7400 RPM
Posted By: 69dart

Re: vacuum pump - when is it needed? - 11/22/14 08:43 PM

Thanks for the info guys!!!

My roadster doesn't have much space for the pump and it doesn't sound like it would add much benefit to my combo.

I seem to blow the evac baffles in the headers every year so I may try the electric vacuum pump instead of the standard header evac IF I can find a place to mount the pump.

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