Crankcase evac

[MaineShark]

I'd like to do something other than PCV to evacuate the crankcase. Here's what I'm thinking of:

Plumb an electric pump (vacuum booster or electric smog pump - not sure what will work best, yet) to a port drilled in the valley cover portion of the intake manifold. That will be where the vapors are drawn from. Plumb a line from the outlet of the port to an exhaust check valve (the things that are used to intall exhaust-powered evac systems), and connect the other end to an AIR pipe, connected to the manifold (the previous owner removed my smog pump). In other words, the pump will suck the vapors out of the crankcase, then pump them into the manifold. The check valve protects the pump from exhaust gas, and the flow into the manifold serves as a convenient place to dump the vapors, as well as having the same effect as the AIR system would, if it hadn't been removed.

To maintain the correct vacuum level in the crankcase (too little, and you hurt performance - too much, and you pull the oil out of the bearings), a hole would be tapped in one or both of the valve covers (back near the firewall, probably), and connected to an adjustable vacuum relief valve. A filter on the other end of the valve would make sure that only clean air is allowed into the crankcase.

Does this sound like it would work?

Ideally, I'm trying to have around 12 pounds of vacuum in the crankcase - if my research is correct, higher (15 or so) would probably benefit a race motor, but I'd like to play it a little conservative.

The second question is is anyone knows of a good pump to use? I'd like to stick with things that I can get from a junker, rather than a race-designed ($$$) pump. The issues that I see are what will pull the right amount of vacuum (at least 15 lbs), and survive the vapor (oil and combustion blowby) that will be run through its guts. Higher flow would be better, as far as helping out in an AIR capacity.

Joe

 

[JohnZ]

That's a lot of work (and money) to spend on a street engine, where you won't need it or see any difference. They have some benefit on an engine that runs all the time at WOT full-load with an efficient low-restriction extractor exhaust system (like a sprint car), but on a street engine that setup is more for visual "wow factor" than functional benefit.

 

[MaineShark]

Well, I'm not planning on keeping this engine stock, and I'll probably be running fairly low vacuum as time goes on, so I don't think that the PCV system will end up working very well, since it relies on manifold vacuum to extract.

There are probably simpler systems than what I'm proposing, but I have this old saying: "If something is worth doing, it's worth doing right." In other words, I like overkill

Joe