pcv or evac:which is better for drawing vaccum?
 

pcv from valve cover to intake or evac from collector to valve cover....what are the diffrences on a bbc with a single plane,dominator set up with a plate.my exhaust is free flowing(no chambered mufflers).



goal: to make cheap mans vacuum pump.....ideas???comments???thx in advance!

at WOT I would think header collector to valve cover would give more vacume. pretty much the same as how a carb works with Bernollis principle.

edit, at idle a pcv probably draws more vacume.

Has anybody tried electric vacuum pumps? There's a guy on RJ selling them for $160. Unless I come across a deal at a swap meet for a mech. pump I will be running the valve cover to collector. I have a motor plate that might make mounting the mech pump a challenge.

Moroso makes a evac kit for about $40 Its the valve cover to collector type, works great at WOT which is when you need it most.
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Use both at the same time.

By theory when one is open the other will be closed.

PCV is open only at times of high vacuum. Pcv is closed during full throttle. Crank evac system is mostly closed at high vacuum and is open when at low vacuum.

Ed

This is the exaust setup I have:

Long tube headers > 3"-2.5" reducer > 2.5" H pipe > 2.5" delta 40's with 3" pipes going all the way back.

Now lets say I properly installed the collector evac kit and ran both of them to one valve cover and the other valve cover would have a hose running directly to intake vac. Does that seem ok?

Should I add a pcv valve, seporator, one way check valve?

http://www.racingjunk.com/gallery/profile/255255

How would you go about plumbing in a setup like that.To pull off one v/c with a pcv,doesn't the other have to have a breather so that it draws thru the engine?Looks like you would need 4 breather holes that way.Not trying to dispite you,just honestly curious.

The only thing I dont like about a pcv system is the oil vapors that are pulled into the intake plenum and intake ports valves etc, which leave nasty flow inhibiting deposits. Rather crap that junk out my exhaust and say adious.......
><Cp

i kinda agree with suckin into the intake tract oily fumes is kinda icky-is it a concern? if not,where to plumb into on my dart tall deck intake?by the way ive also got a nitrous plate kit on...what is opinions of electric vacuum pumps?if i just run evac to header is it ok to just use one valve cover lined down to one collector(cause i have air to fuel ratio sensor welded in one collector already)

:idea: So when is someone going to step up to the plate and get a patent on a AFFORDABLE electric or belt drive evac pump for the high performance street guys and become a multi millionaire?

I would do it but I dont have the funds to get it started

If your really crafty you can go to your local bone yard, fab up some brackets to mount a old smog pump and use the suction side as a low buck vacuum pump. Works good and I've seen many used like that especially at my hometown redneck track here in north missisppippi, I've always used the header evac set up for my cars and I've never had any problems with them personally and I dont see why you should be able to use just one side of the engine if one of your collectors is tied up with a ego sensor. I've also seen then use old blower motor fan motors as water pump drives, I'm just a little more picky about how my stuff looks but hey if it works use it. ><Cp

If your only racing, WOT is the only thing a race engine sees. The basic valve cover to collector evac is excellent. The issue comes up when you stray from the track and go for a cruise on regular civilian roads. Even if for a couple of miles , the evac then isn't working at 100% between idle and WOT. that is where the mech pump's all time presence helps from fouling sparkplugs and causes gaskets to weaken and leak. I am really interested in hearing if anyone runs an electric version. I will message the guy on RJ that is selling them to see if he will give us some feedback.

they have GZ Motorsports makes a affordable belt drive set up. I would run without a vacuum pump anymore, very good investment

I was thinking more affordable as in $150 for 12" of vac.

I ended up purchasing 2 of the Mr gasket kits http://www.jegs.com/webapp/wcs/store...-1&showValue=1

and modifying the 4 tubes with venturi holes to make better use of the exaust pulses. Im going to weld a 1/2" long piece of 3/8 tube over the venturi holes to help capture/accelerate more energy.

Whenever this happens I will hook up a vac/boost guage to the crankcase and post some video results of it in action[/img]

Where would I put the backfire valves on my car?My collectors are 10" long,then there is a 24" straight pipe and ends at a turndown?No muffler.Would it still go in the collector,or towards the end of the entire works?

well I`ve been using an elec GM air pump (vac pump) with a voltage reducer to keep it running cooler,,pulls lots of vacuum, and I run the system open with a lite restriction on the intake end,,pulls way more than the header style evac,,,maybe 10 times more,,and you can mount the pump were ever you want,,only draw back is you need a good separator tank,,I use it mostly just for the track,,,and it works great,,,,pulls as much vac as my bros aerospace one,,and at least 1/2 the cost

Sweet, I needed to hear from someone who uses the electric version. I just bought Borla header collectors which don't have the fitting and I am not tearing them up, so I have to run a vac pump. If I can't find a good deal on a mech I am definately using electric.
Thanks superstreeter.