[Formulajones]

Originally Posted by HWYSTR455

Why in the world would anyone need 10" of crankcase vacuum? Especially on a street car?

I realize a pcv can draw that much, maybe, but still see no benefit from 10". Even with super light rings, you don't need that much. That's why most only draw a couple inches.

I was under the impression that people who do 'need' to run them are blow-thru cars, but I could be mistaken. Maybe I need some schooling on that...


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From everything I've seen it's pretty typical to have 10-12 inches at WOT being the desired amount at peak rpm. Now when idling or cruising you don't. Maybe a few inches is all that is needed there.

Dad runs a mechanical vacuum pump on his street engine. Now at first he ran a PCV and it was fine, and it was run on the dyno that way. But Tony told him the benefits of having one and eventually dad wanted to try.
The mechanical on there, once the pulley ratios are right, only pulls about 4-6 inches idling and cruising slow speeds. As engine rpm increases, so does the vacuum pull. At peak rpm (6,000 rpm in his case) it's pulling 11 inches. So it's a gradual climb to peak through the rpm range. It's not 10 or 12 inches all the time. That's how they are intended to work.

He's been running it on the car, on the street, for maybe 3 years now. Works very well.

For an electric pump to work like that on the street I would think it would need some sort of controller to work with rpm and increase voltage and vacuum pull as rpm increases. It won't be as simple as just hiding a vacuum pump and wire it up type of deal.