Intake vacuum hg?

[RacerX]

What is the typical vacuum in the plenum? Thanks!

[TFB]

Gee I dunno, my vac gauge always seems to be over on the pressure side...

[RacerX]

Cute! Bet mine has more ponies with vacuum than yours does with pressure! :D Not that a 200 shot has anything to do with it...

[RR|Suki]

about 20in.hg at idle for me, after a run when the I get off the throttle it'll got to 25 during decel, then back to 20.

[thathotrodlincn]

Typically NA: mid 20s at idle. Trilogy/Eaton SC: 20+/- at idle. Not familiar with centrifugal. Hope this is what you need.

[RacerX]

Perfect! Thank you much! :)

[TFB]

Cute! Bet mine has more ponies with vacuum than yours does with pressure! :D Not that a 200 shot has anything to do with it...
Yeah I get that, but if you're injecting the juice when there is vac in the manifold, you're going to have a problem...

[RacerX]

? That's how it gets to the cylinders, negative pressure pulls the N2O and additional fuel in along with the normal air charge that's constantly being sucked in with an N/A engine. Manifold and plenum are being referenced as on in the same here. ?

[TFB]

Basically at WOT there should be no vacuum in the manifold, just the air flowing into each intake port... If there is vac, then you have a restriction in the air flow path(dirty air filter, too small throttle body, etc)...

[RacerX]

Ed Zachary, that's why the 90mm MAF is going in... ;) Velocity and volumetric efficiency, blah, blah...

[FordNut]

Stock cams about 20" with closed throttle at idle. Maybe a little higher closed throttle on decel.

Mine is more like 16-18".