wierd exaust setup??? WTF???

[bigbadchev84]

i was over at a buddies house the other day checking out his new mud truck he just picked up, i was looking it over when i noticed the headers right before the flange hade a 1/2 pipe nipple welded into them with a valve on top, then a hose went from the valve to the pcv valve. i asked him what it was all about and the guy he bought it from said it was good for an extra 20hp because the valve is a one way valve and it sucks the pressure out of the crankcase with the exaust. i have never heard of such an idea. does this make any sense?

 

[mikey_d05]

Did it have NOS stickers?

 

[RustBuket]

I would think it would pressurize the crank case instead of depressurize.... hmmm well maybe the flow past the nipple creates a vacuum.... I dunno sounds iffy to me.

 

[bigbadchev84]

it has a check valve installed it is a pretty wicked smallblock 400

 

[mikey_d05]

I could see how if the valve was installed the right way at the right place it MIGHT create a vacuum. However, there is no realistic way that that would be worth 20 horsepower.

 

[bigbadchev84]

it sounded wierd to me and i have never seen such a thing, the truck is somthing else its got 42" tsls a 6inch body lift, no bed, 4" suspension, welded60/14bff,400/205 they call it the bean burrito

 

[pauly383]

Its been around forever . Pulling vacuum increases ring seal and helps prevent oil leaks . Do a search on the internet , real big on old British bikes . Just don't do it during break in of a engine .

 

[mikey_d05]

Its been around forever . Pulling vacuum increases ring seal and helps prevent oil leaks . Do a search on the internet , real big on old British bikes . Just don't do it during break in of a engine .

True, but it adds 20 horsepower?

 

[4X4HIGH]

Mosr race cars use that system to remove crank case pressure. The valve is nothing more than a one way smog pump valve attached to the exhaust near the header collector to scavenge any pressure or vapors from the crank case. If you look at race cars you will usually see a large clear plastic tube attached to the valve covers and goes to this valve near the bottom of the headers.

 

[k5freak44]

True, but it adds 20 horsepower?

If the "As seen on TV" pattented Tornado gives 35 hp that setup should add atleast 15.















If its chrome then tack on an extra 7hp per square in of chrome














ive never seen the setup, but it sounds like it could work

 

[bonanza]

That's a crankcase evacuation system. It works on the same principle as a paint gun. The high velocity exhaust gases can theoretically create a certain amount of vacuum in the crankcase. This allows for a better piston ring seal. It allows using lower tension piston rings without creating excessive blowby. Drag racers have been using these for years. However, they aren't extremely effective, which is why many drag racers have used vacuum pumps instead. On the street, these do not work. A street engine does not run at high enough RPM's for them to be effective, so you would be better off running a regular PCV setup. In other words, the guy your friend got the truck from was an idiot.

 

[resurrected_jimmy]

I read an article on vacuum pumps not long ago in Engine Masters. On a test they did, a vacuum pump pulling 9 inches vacuum on 355 sbc "street engine" was worth an average of +6 hp and +6 lb ft torque. Max this engine made +14 hp@6400 rpm and +12 lb ft torque@6200 rpm. The set ups they were describing cost between $600-$1000. In the tests they did the only one I saw with over +20 hp was a 556cid bbc "hard core race engine." It gained 32hp@6800 rpm with 12.5 inches of vacuum.

 

[4X4HIGH]

On the street, these do not work. A street engine does not run at high enough RPM's for them to be effective,

RPM's have nothing to do with exhaust scavenging. As long as there is exhaust coming out the header it WILL pull vapors from the crankcase.

 

[RustBuket]

RPM's do have an effect! More flow by the valve would equal more vaccuum!

 

[4X4HIGH]

RPM's do have an effect! More flow by the valve would equal more vaccuum!

This may be true but bonanza said it is not effective on a street vehicle which is incorrect.

 

[thor]

Quick question.... How many of you that say they don't work have ever run them?

Now with that out of the way... They will work at low rpm with an efficient flowing exhaust, they scavenge better at rpm but your engine will also develope more blow by at rpm. On my 540 chevelle they pull enough vacuum at idle to suck the breather to your hand, I'd like to see a PCV do that....

 

[4X4HIGH]

I know your question is directed at people who say it doesn't work but just thought i would add that i myself have done it on a HOT street car and it DOES work.

 

[K5er4Life]

One of my friends used to have a blown 454 in his '71 chevelle, he was getting some nasty oil coming out of the breathers and the thing leaked like a crazy. We were at our local speed shop when this older guy told us about this setup, he said it would take care of the excess oil. My friend bought this little kit while we were at the speedshop (came with check valve, hose, and breather cap with fitting) and sure enough once it was all together the oil stopped. I have no clue whether or not increases horsepower, if it does its probably negligable at most, but I do know that it definitely helped to relieve pressure in the crankcase. I dont really see many engines that dont leak oil around the grommet in the breather cap. Its annoying as hell too, always having a shiny new motor just to eventually get oil on it, then comes the mud.

 

[highrider_44s]

This is the first i've herd of this setup. But the therory sounds good. Weather or not there in a noticable increase hp probably relates more to your application.

 

[bonanza]

This may be true but bonanza said it is not effective on a street vehicle which is incorrect.

I might have said that it is not effective on a street setup, but you are taking it out of context. What I'm saying is that it would not create any large measurable increases in power. And I'm also referring to a streetable small block chevy. These are my only experience with a pan e vac system. Of course a big block will be more responsive to this. The same modification made on a small block will often make more power on a big block. This is simply a function of cubic inches. RPM's DO have a direct affect, this is because higher RPM's mean a higher exhuast velocity, as does smaller diameter collectors.