Ported Vacuum at WOT?
Thread Starter
Melting Slicks
Joined: Nov 2000
Posts: 2,738
Likes: 53
From: Bogart GA
Ported Vacuum at WOT?
I know manifold vacuum goes to zero at WOT and ported vacuum starts at Zero but as the throttle blades are openned, vacuum increases. Does ported vacuum drop off at WOT? My guess is it does not. Lars tech article states that max performance at WOT will be had at 36 to 38 degrees total advance. This would be covered by the mechanical advance alone. If you add the vacuum advance to this , you would be at 50+ degrees total at WOT!
Something to think about. You can run manifold vacuum but some engines will not like a lot of advance to soon. Mine seems to like it. :D
Something to think about. You can run manifold vacuum but some engines will not like a lot of advance to soon. Mine seems to like it. :D
Melting Slicks
Joined: Mar 1999
Posts: 2,845
Likes: 2
From: Apex NC
Re: Ported Vacuum at WOT? (KJL)
Ported vacuum is only present in part-throttle situations. When the butterflies in the throttle body open further, the venturi effect is reduced and the vacuum at the port diminishes.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Ported Vacuum at WOT? (KJL)
As soon as the throttle blade is cracked open to expose the ported vacuum port, the ported vacuum acts exactly the same as manifold vacuum. There is no ported vacuum at WOT, just like there is no manifold vacuum at WOT.
