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Post by charlie1 on Nov 4, 2004 0:00:14 GMT -5
Is a PCV valve required on a performance street engine??
And if so what is its value or consequences for not operating with a pcv valve.
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Post by Don on Nov 4, 2004 9:24:25 GMT -5
Yes, some sort of Crankcase evac system must be used or you'll build too much pressure and have problems with oil leaks.
You can just vent the motor but you'll be leaving a trail of smokey smelly vapor behind you.
The old cars had a tube that went down the back of the engine dumped the fumes under the car...and coated the chassis with oil film.
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Post by rumblefish360 on Nov 4, 2004 18:31:54 GMT -5
The best bennifit to a PVC valve is it helps keep the inside of the engine cleaner by removing the smoke built up inside from the oil.
All though it's being swallowed by the carb, it doesn't give any noticeable effect on performance.
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Post by Don on Nov 9, 2004 6:32:12 GMT -5
Sort of like driving in LA
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Post by strokie451 on Nov 13, 2004 9:09:20 GMT -5
I use 2 breathers (no pcv) on my 451 stroker and I don`t have any fumes. Total seal rings help to reduce blow-by. Pcv is good to reduce emission. Pcv is bad for performance engine,the contamination of the air fuel mixture with oil fume is not the best octane booster... I think on a new engine you don`t need pcv,but when the motor wear=more blow-by you need a pcv.  |
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Post by charlie1 on Nov 15, 2004 18:31:31 GMT -5
Thanks for your input guys.
This now brings up another question as from doing a bit of research "When using a PCV valve the partial vacuum in the intake manifold will keep the crankcase at a slightly negative pressure, improving the piston ring seal"
I have also seen setups where they are using both a PCV valve as well as a breather, but using the above info is this negating the pcv valve opertaion?
So should i have 1 x Breather ( which side?) 2 x Breathers?
Or 1 x PCV Valve (which side?) or 2 x PCV valves into common intake manifold port.
I agree with Strokie 451 when using a pcv valve that you are putting these fumes back into your intake and effecting you mixture.
P.S I'm talking about a fresh motor, new rings, hone,etc
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Post by Don on Nov 17, 2004 10:33:53 GMT -5
Correct....but the evac ability of a little PCV is limited and will relieve some pressure but I doubt it will actually pull a vacuum of any consequence in a peformance motor.
If you want to vacuum your crankcase you should use an EVAC system off both valve covers into the header collector, that will give you 5-15 HP depending on the severity of the crankcase pressure.
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Post by Chryco Psycho on Nov 26, 2004 2:10:41 GMT -5
the stock system is designed to pull in clean air from 1 side & evac from the other side through the PCV valve , which side makes no difference
removing pressure from the cranck case will help the oil rings do there job & free up power
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