Quote:
Originally Posted by RTTTTed
If you could actually evacuate all the positive pressure from the crankcase the "effective" compression ratio would be higher without the problems caused by detonation allowing more advanced timing. A vacuum in the crankcase would actually suck the pistons down and create hp - not likely in real life. There's too much 'blowby' past the rings to get a vacuum in real life. Breather's are OK for relieving excessive pressure, but not recommended. The PCV works well and would help remove a little of the crankcase pressure.
My car has a vacuum pump mounted beside the radiator. The valve cover breather hole has been enlarged for a bigger than stock fitting and 5/8" ID braided hose to the vacuum pump. The vacuum pump uses another 5/8" braided hose to the 'puke tank' mounted beside the rad on the driver's side near the bottom. The puke tanks drain **** is attainable from under the car and easy to drain. This daiphram vacuum pump sucks so much air that when it's on air can be heard rushing into the oil dipstick tube when the dipstick's pulled out.
This is the best system I've seen, looks good and I expect that it adds probably about 5+hp. I'd include a pic, but all that's visible is the fitting and hose leaving the valve cover and it disappears down beside the cover.
Fatherford's illustrated system is a Racing system and uses a corvette (or similar type) 3/4" PCV welded into the header collectors at an angle creating a vacuum at the tube opening. The Pollution Control Valve is to protect the engine by closing off in case of a backfire which could blow out all your gaskets if the flame gets to the oil fumes in the crakcase. Usually 1 badkfire and the PCV blows out however. This system is OK on a race car where Blue smoke out the exhaust is OK, but in a street application it has a tendency to suck oil droplets out of the engine and cause the smoke at the tailpipes. Definitely will not pass any emissions test. Also may get you pulled for a pollution test when blue smoke seen coming from your tailpipe, in some areas.
Ted
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That setup I shown is used on many mustang TT setups. I haven't heard of any issues of not passing emmissions. Then again with TT mustangs usually a little oil drop here and there is the least of their problems when it comes for inspection time. I know I personally have never seen any blue smoke come out of my tail pipes with this setup. So weather emmissions would be a problem
Also, when I was doing a little part time out at the machine shop in my teenage years, when putting 10-12" of vacuum on some healthy v8 engines we noticed upwards of 15-25hp at the flywheel on the engine dyno. This was using a vacuum pump.
Using the method I had in the drawing on boosted mustangs Pushrod/mod motors both, I have seen 21". Which you need to put a valve in to "bleed" off the vacuum and limit it to 12".