What else is our there besides PCV systems? I'm creating this topic to better understand why a Crankcase Evacuation System would not be feasible on a street car. For reference, I'm talking about this (not to be confused with a PCV system): Moroso Crankcase Evacuation System or Mr. Gasket Crankcase Evacuation System What are the pros and cons of using this? I want to hear what people say who have used them. Would it really create to much suction on a streer car? IHI states this in the tech / General Engine forum: Quote: On a typical application they will show very minimal gains in the hp department-and that's a motor built knowing a vacuum aid such as this will be used, there just is not enough suction created with this set-up. Only a real vacuum pump designed to do just what yout trying and a regulated valve on the valve cover will net you the gains your looking for from just sealing the rings better...but again, that's assuming your motor's rings are either shot and leaking right now or you had the short block built loose knowing you'd be using a external vacuum source to compensate for the loosely built engine. -IHI Does this hold true? Anyone beg to differ? Is what IHI said is true, would there be a way to regulate or control this? For the purposes of this thread, please keep your "PCV system is more than efficient" comments. -Thank you

This is all true:
On a typical application they will show very minimal gains in the hp department-and that's a motor built knowing a vacuum aid such as this will be used, there just is not enough suction created with this set-up. Only a real vacuum pump designed to do just what yout trying and a regulated valve on the valve cover will net you the gains your looking for from just sealing the rings better...but again, that's assuming your motor's rings are either shot and leaking right now or you had the short block built loose knowing you'd be using a external vacuum source to compensate for the loosely built engine.


The valves work MUCH better when there are crisp pulsations across them. Adding anything in the way of a muffler dampens the pulsations, from what I've seen. I've tried them on several street cars with min results.

Using one of the later vacuum pump systems, IMO, is the way to go.

I see your point. But let us say you are more interested in engine life than how much HP gains you would get from a system. Excluding an air pump, let us compare and contrast the PVC system verses the Crankcase Evacuation System. Both are not pricey compared to the air pump option. Which is better and more ideal and why?

These are both little more than variants of the old Pulse-Air systems used for air injection. They will create very little actual pressure differential (vacuum) compared to even a stock PCV system. The one thing they can do is flow more air, so under situations of excessive blowby from boost, "loose" (forged internals) builds designed for boost, or excessive wear, they can reduce crankcase pressure. They will not create any appreciable crankcase vacuum, however.

I strongly suspect they are not emissions legal, either, since the gasses are not subjected to the combustion process. If you are thinking of this for the street, it might get you into trouble. If you are thinking of this for serious racing, it probably won't quite serve the purpose you intended. A positive pump will create both adequate flow (like these passive systems) and allow a measurable vacuum (like stock PCV systems) so that gas pressure in the crankcase is miimized. For a moderate build, off-road duty, and moderate use, these systems might help. Maybe.

I wouldn't use it on a street car.....def not gonna be emissions legal. My buddy ran one of these setups on his car (N20 306, 10.30 133 mph) and he said it worked great at wide open throttle, but around town not so well. I was interested in something like it when my old motor was giving up and had all sorts of blowby. Basically came to the conclusion it wasnt worth it on my setup.