Crankcase evacuation systems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Garagedude · 04-04-2009, 10:48 PM

I have been doing some research on them and have seen a bunch of guys running them. Is it practical to run one on the street? Any info you guys can give me would we be great cause I am kinda confused, I understand what they do, but I also have heard they can hurt your setup. Thanks Steffen

Lx3 · 04-05-2009, 08:37 AM

I've been told an evac system doesn't start working till about

6 grand and are not necessary on the street. I've been told.

Lx3 · 04-05-2009, 08:40 AM

What I meant was a race style evac. You have to have some sort

of stock style. PVC and breather

Marv D · 04-05-2009, 11:01 AM

I agree, on the street a stock style PCV system is much better. In some applications you don't have that option, and the header evac system is better than 'nothing' but that's about it. There are tricks to place the evac tube so that will help a little. (make sure you have the 30° minimum angle and scallop the back side so the passing exhaust flow created a larger pressure drop on the downstream side,, etc). I draw 4-5" of vacuum at the evac tube with a header evac system and it helps keep things from slobbering oil all over. One thing to be sure of,,, the Mr Gasket push-in chromed breathers are total GARBAGE, leak like a sieve. Go to the parts store and get the 'real' Mopar breathers. Paint them, have them power coated, or whatever, but if you use a leaky breather you will barely pull any vacuum at the crank case.

If your talking a belt driven vacuum pump..... DEFINATELY not a street. item. The old A.I.R. injection pumps converted to be used as a vacuum pump just don't work, and the stand alone systems like Aerospace billet pump, brackets and all will set you back nearly a grand, and you HAVE to pull oil through them or they will burn up, and the big Moroso pump and dry system oil pump... well it's just not a street item either. Maintenance on those will convince you of that in a hurry.

All that to say.,...... A stock PCV system is pretty hard to beat on the street, even if you package is low on idle vacuum.

Oh, and you'll see reference to guys running the electric vacuum puimps off the recent LS packages. Don't know anyone who has been successfull at that. Many have tried, but haven't heard anyone who was happy with the results.

Garagedude · 04-05-2009, 11:25 AM

Thanks Marv for all the info, I am just going to continue to run the pcv system sounds the most ideal for my application.

04-04-2009, 10:48 PM	#1
Garagedude Registered User Join Date: Aug 2008 Location: Summerville SC Posts: 217	Crankcase evacuation systems I have been doing some research on them and have seen a bunch of guys running them. Is it practical to run one on the street? Any info you guys can give me would we be great cause I am kinda confused, I understand what they do, but I also have heard they can hurt your setup. Thanks Steffen

04-05-2009, 08:37 AM	#2
Lx3 Registered User Join Date: Nov 2008 Location: Ponder, Texas Posts: 94	Re: Crankcase evacuation systems I've been told an evac system doesn't start working till about 6 grand and are not necessary on the street. I've been told.

04-05-2009, 08:40 AM	#3
Lx3 Registered User Join Date: Nov 2008 Location: Ponder, Texas Posts: 94	Re: Crankcase evacuation systems What I meant was a race style evac. You have to have some sort of stock style. PVC and breather

04-05-2009, 11:01 AM	#4
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: Crankcase evacuation systems I agree, on the street a stock style PCV system is much better. In some applications you don't have that option, and the header evac system is better than 'nothing' but that's about it. There are tricks to place the evac tube so that will help a little. (make sure you have the 30° minimum angle and scallop the back side so the passing exhaust flow created a larger pressure drop on the downstream side,, etc). I draw 4-5" of vacuum at the evac tube with a header evac system and it helps keep things from slobbering oil all over. One thing to be sure of,,, the Mr Gasket push-in chromed breathers are total GARBAGE, leak like a sieve. Go to the parts store and get the 'real' Mopar breathers. Paint them, have them power coated, or whatever, but if you use a leaky breather you will barely pull any vacuum at the crank case. If your talking a belt driven vacuum pump..... DEFINATELY not a street. item. The old A.I.R. injection pumps converted to be used as a vacuum pump just don't work, and the stand alone systems like Aerospace billet pump, brackets and all will set you back nearly a grand, and you HAVE to pull oil through them or they will burn up, and the big Moroso pump and dry system oil pump... well it's just not a street item either. Maintenance on those will convince you of that in a hurry. All that to say.,...... A stock PCV system is pretty hard to beat on the street, even if you package is low on idle vacuum. Oh, and you'll see reference to guys running the electric vacuum puimps off the recent LS packages. Don't know anyone who has been successfull at that. Many have tried, but haven't heard anyone who was happy with the results. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

04-05-2009, 11:25 AM	#5
Garagedude Registered User Join Date: Aug 2008 Location: Summerville SC Posts: 217	Re: Crankcase evacuation systems Thanks Marv for all the info, I am just going to continue to run the pcv system sounds the most ideal for my application.



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