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Re: Crank case evac on street/strip car. Help me out please
[Re: 69charger440_6pa]
#212086
02/03/09 09:50 PM
02/03/09 09:50 PM
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Joined: Jan 2007
Posts: 7,664
IN
ahy
master
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master
Joined: Jan 2007
Posts: 7,664
IN
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Quote:
Hey,
So I have been wondering, what is the best way to vent the crank case on a street strip car? I have a solid cammed 493 street/strip engine. Right now I am running a breather on one side and a pcv on the other. Are there better ways to do it?
Dual breathers?
Crank case evac using the headers?
Vacume pump?
Thanks alot
Another perspective. If you are using a standard ring pack - not low tension - and parts are machined correctly there shouldn't be a lot of blow by on a street strip engine. An evac system or vacuum pump isn't really needed and wouldn't help much with a typical engine. On a race engine with low tension rings it could help a lot.
The benefit of the PCV valve + breather is constant changing of the air. The PCV sucks some out and the breather lets some in under light load. This helps remove moisture and other bad stuff. Under heavy load, blowby can still exit the breather. Unless you are having a particular problem with your setup I'd just run it. That's what I'm using on a 496 without problem.
Two breathers would work OK also but you don't get the benefit of circulating fresh air through the crankcase.
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Re: Crank case evac on street/strip car. Help me out pl
[Re: BEEQUIK]
#212089
02/03/09 10:26 PM
02/03/09 10:26 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Quote:
this may not help anyone but let me tell you what happened to me and maybe someone will be able to tell me what happened.
I had a moroso crank case / header evacuation setup on my 68 GTX.Car ran mid- high 11's and we went to a track for a muffler race. I had an exhaust system put on the car 2-1/2 " with flowmasters.Man it sounded good and when I made a pass it was a SECOND slower,and it blew the intake valley pan up like some stovetop popcorn,all bulged up and blew out the valve cover gaskets!! Unhooked the exhaust and back to 11.70--  
Very simple, your 2 1/2" with Flowmasters had more
back pressure than 5"hg, once you got on it it went
above 5"hg and the back pressure burnt out the check
valves and pressurized the crank case
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Re: Crank case evac on street/strip car. Help me out pl
[Re: BEEQUIK]
#212090
02/03/09 10:33 PM
02/03/09 10:33 PM
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Joined: Oct 2004
Posts: 8,165
Left Coast
BobR
master
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master
Joined: Oct 2004
Posts: 8,165
Left Coast
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Quote:
this may not help anyone but let me tell you what happened to me and maybe someone will be able to tell me what happened.
I had a moroso crank case / header evacuation setup on my 68 GTX.Car ran mid- high 11's and we went to a track for a muffler race. I had an exhaust system put on the car 2-1/2 " with flowmasters.Man it sounded good and when I made a pass it was a SECOND slower,and it blew the intake valley pan up like some stovetop popcorn,all bulged up and blew out the valve cover gaskets!! Unhooked the exhaust and back to 11.70--
Baffled mufflers like Flowmasters DO NOT WORK on evac systems. To get any real power gain you need to use a low tension oil ring and a mechanical vacuum pump that pulls 15" or more vacuum. This much vacuum also helps seal the whole ring pack.
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