Some recommend using the electric vac pumps that came on GM cars, while others say they don't pull enough vac to be effective.

I've heard mention of using a belt driven Ford AIR pump, but haven't found any details.

What's everyone's experiences?

 

For a street car, you won't notice any difference.

 

Just trying to gain an advantage when I do go to the track.

I guess all the claims of increased hp are inflated?

I've also read where some of the supercharged/turboed guys run them just to keep from pushing out gaskets, etc.

 

A prostock engine may see 20-30 HP increase. A street engine will see little to no increase.

I run an electric vacuum pump. With the engine off, it barely pulls 5 inches of vacuum. I never checked it with the engine running. The main reason I run a vacuum pump is to pull the condensation and alcohol vapors out of the crankcase after a run. Running alcohol, it's hard to build engine heat to burn off the moisture.

A belt driven pump is better because it's variable speed, the faster the engine spins, the faster the pump spins and the more vacuum it can pull. Pulling more than 18" can suck the oil from the bearings so a vacuum relief valve is installed in a valve cover. A belt driven pump can't be used to pull the moisture out of the crankcase when the engine is off.

There are a few belt driven pump kits available. The pump itself isn't too much but you would need a complete installation kit. These are the 3 most popular pumps used.

http://www.jegs.com/i/Moroso/710/22640K/10002/-1
http://www.gzmotorsports.com/vacuum-pumps.html
http://www.starvacuumpumps.com/

ProStock cars use the Star 24 volt pump.

 

Thanks.

I still have the bracket for the stock AIR pump and could probably make something work with it.

I see the pumps in the second link can be had with a serpentine pulley, so it might work.

I have one of the electric pumps and tried it on the previous setup and noticed no improvement in performance. Guess it didn't pull enough volume.

 

I did some research on this a while ago. I think you really need to be pulling at least 7 inches to notice any power. The problem with most factory smog pumps is that they don't like to get any oil in them, so you need an oil separator. The ford belt driven ones seemed to be the most popular (pull more vacuum) until GM started making the new electric ones. Started around 2002 or something. I dunno I found it all on yahoo. Its really not worth the trouble.

Blower/turbo guys like em because you get an increase in crankcase pressure from ring blowby. I"ve tossed around the idea of trying it, but I don't see the point. I'm not going to notice the power increase and once I get the rest of my mods done, I should be well into the 9's so, eh.

I read a good place to check vacuum is off the fuel pump plate.

 

I check vacuum at the dipstick tube but then I only check it when the hood is up.

One advantage to using the electric pump was that I was able to track down an oil leak easily. With the engine off and the pump on, I was able to hear a sucking sound. It was coming from the oil pan rear seal. Changed the gasket and the sucking sound went away.

 

Oh that was another thing I read. The motor needs to built with the pump in mind to keep it super tight and air leak free. Else your just sucking air through the motor.

 

unless the motor is high compression or utilizing a power adder it wouldnt be worth it. There are some kits out there for electronic pumps built for this purpose, jegs sells one around $400. I would use a purpose built pump rather than the junk yard method.

 

Don't waste your time and money unless it's a purpose built race engine with low tension rings. I tried the Moroso belt-driven pump on my LT1 and lost 1 rwhp on the dyno. The motor was very tight and I ran a vac relief valve to limit the vac to 13"Hg.