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I was watching spike tv's horsepower this past sat. They were building up a camaro "wish they would do more fords on those shows". They used a special made system to draw the crankcase gasses out. It was a belt driven vac pump with a condensor built into the system to remove the oil vapor. It made me wonder if that type of system could be used to replace the cdr on our trucks.
The condenser is a good idea, shouldn't need a vac pump, the intake will pull sufficiently unless the condenser design restricts airflow that much. There are systems out there, and they can be pricey. I was going to add one to my truck, but haven't found the money, or time.
Several designs are out there for garage built units. Some people plumb these things down to the frame to let the oil vapor cool and drop out of the airflow. I would think thats not totally necessary, and liable to cause freezing issues in some climates. You wouldn't want the tube to freeze solid and block off the engine venting (great way to blow seals).
I was reading some on the use of the pumps (on gassers). They claim that there is an increase in hp with the vac in the crankcase. Not sure yet how this happens or if it is true. But if it deletes thye pita cdr and increases the power, then I think I will try to come up with something. I noticed that the vac pump on the 7.3 is up top driver's side. I may try to use one for this app.
One thing I swore I read somewhere was that the CDR restricts the amount of vacuum going to crankcase, I'm guessing(but no clue) that the PCV valve on a gasser does the same. Something about too much vacuum can harm the seals, or maybe suck in dirt that gets near the seals? I might be wrong though.
I wonder if the increased performance is more from cleaner air. Like instead of sucking some oily vapors and what not from the crankcase, it would be all clean outside air. Otherwise I'd think the oily vapors would add a little more fuel, and actually help the engine. Honestly though, I'm not a performance guy, I just want to cut down on the oil thats getting sucked into the intake and leaking around the turbo.
The CDR does restict the amount of vacume in the crank case if it wasn't there any you just had a tube to the intake at high rpm there would be enough vacume to suck lots of oil into the intake.
As far as pulling a vacume on the crankcase increasing HP it takes HP to dive the pump and while in THEORY vacume COULD help pull the piston down it doesn't because the same force would be pulling down on any pistons going up negating any movement asociated with the vacume.
On second thought the vacume could increase HP since in a vacume there is les friction but I doubt it would be enough to overcome the HP taken to drive the pump.
My Evac setup consists of two VC breathers, a homemade seperator that mounts on the upper firewall above the engine that is half full of packed steel wool, separated with perforated metal, its about the size of a beer can. Then the inlet to the seperator is plumbed into the inlet tube of the turbo. Pulls pretty damn good vacuum even at idle. Im sure its more than effective. Pulls more vacuum than the exhaust evac that I had on there beforehand.
The purpose of the pump is to create a vacuum inside the crankcase/oil pan region. High horsepower, high compression, high rpm, engines create a lot of blow-by inside the crankcase; in many cases that blow-by actually creates a positive pressure situation inside the crankcase. Blow-by steals horsepower, causes your engine to leak oil, and contributes to a lot of the contaminates that get in your oil. If you can create a negative pressure inside the crankcase the piston rings seal much better and blow-by is drastically reduced. The increased ring sealing capability increases horsepower by about 4 and in some cases probably as much as 7%. A normal 500hp engine with a low tension ring setup could probably see a 12 to 15 horsepower gain by running a vacuum pump. Vacuum pumps really got their jump start many years ago in the NHRA sportsman divisions; since that time they have become a mainstay in the Pro Stock division and as they have become cheaper to buy a lot of bracket cars run them.
As far as a diesel application not sure, i know they work on 1000 hp big blocks at 6000rpm LOL , but because of the low rpm range of the diesel i dont think it is a real issue