when do you use a vacuum pump?

Have a 533 in a drag car an was wonderin if a vacuum pump would give me some more horse power? Thanks

some say a pump will get a few hp but for me,running alky,it keeps the oil clean.another thing is how much it'll do for oil leaks.

yes a vacume pump is need for wide open runs when you are wot the pvc valve will not do the one more thing you can do it put a evac system on it and let the exhaust do the work at wot ON the hp gain i cant say but after a while it may hurt the hp without it if you blow a seal like Lee said

Just got my 522 dynoed and the header style evac made 1" of vacuum. Enough but not enough to make the available horsepower that a pump would make. Told me the pump would pick up 15-20 hp. The header evac did 6 hp on dyno.

70FB wrote:Just got my 522 dynoed and the header style evac made 1" of vacuum. Enough but not enough to make the available horsepower that a pump would make. Told me the pump would pick up 15-20 hp. The header evac did 6 hp on dyno.

that whst i started out with is the header evac now i run a eletric vacume pump plus like Lee said it helps when running alky or the e85 deal as i can leave it on and.pull moister out of the crank case after a run to help the oil out after i shuit the engine off

cool40 wrote:some say a pump will get a few hp but for me,running alky,it keeps the oil clean.another thing is how much it'll do for oil leaks.

X2

69F100 wrote:

70FB wrote:Just got my 522 dynoed and the header style evac made 1" of vacuum. Enough but not enough to make the available horsepower that a pump would make. Told me the pump would pick up 15-20 hp. The header evac did 6 hp on dyno.

that whst i started out with is the header evac now i run a eletric vacume pump plus like Lee said it helps when running alky or the e85 deal as i can leave it on and.pull moister out of the crank case after a run to help the oil out after i shuit the engine off

How much did it pick your times up?

not sure as i was having carb troubles at the time i installed then made the switch to alky i can say if i happen leave it off i loss about .010 off my time if that helps you any

Thanks thats what i thalt. Got the header evc system now an seem like its not doing the job so time for a pump.

I don't think ~20 hp gain would be out of question with that size engine. 25ish hp on 598"-632" engine is possable.

Lem Evans wrote:I don't think ~20 hp gain would be out of question with that size engine. 25ish hp on 598"-632" engine is possable.

Does an electric pump have a cost advantage until you get to a certain cubic inch such as (anything over 600" you would want to run a belt driven to have more pull as rpm increases?

The cheap electric pumps won't make alot of vacuum on a large engine. The belt driven pumps are the way to go if one is looking for a nice power gain i.m.o.

Lem Evans wrote:The cheap electric pumps won't make alot of vacuum on a large engine. The belt driven pumps are the way to go if one is looking for a nice power gain i.m.o.

Just adding to Lems statement

The stock application ones, were to do nothing more than the PCV valve, to simply vent fuel vapor. Two can add up to a little vaccum, but still not worth the cost, nor headache. A belt driven application will actually allow a negative pressure in the crankcase and can support low tension rings if thats the desire.

elec smog pump del is worth 5" max if that.

Thanks guys, I'll be shopping now.