Electric vacuum pump vs. EVAC

There's a big difference between an electric vacuum pump (like for accessories such as brakes, etc) and a competiton vacuum pump, and the EVAC systems. The vacuum pumps cannot move enough air to pull vacuum in the crank case. And that is what helps the rings seal to make more power. The EVAC system will not pull enough air to do that either. It does work well, but there is only so much work exh gas flow can do for you. The valves can be gotten in diferent vacuum ratings. I think looking up Ford Air Pump Check Valves were where I've found the varous ones. In any event, a real competition crankcase vacuum pump will pull a decent consistant vacuum. That's what you need if you are looking to take advantage of it. I think for a typical small block the Moroso 3 vane would pull enough air to get 12-15". Not sure what this one can do but it's electric: http://www.fastbygast.com/Catagories/Products/description/vacuum.asp
You could also just spring for a dry sump system to make more power and pull vacuum at the same time. Again, won't pull serious vacuum (most guys from what I can tell want 15-20") but it should get past 10".