Vacuum during driving

[Sabz5150]

Quick question... I noticed that at high RPM's, even with the pedal to the floor, as the tach rises, the engine will slowly start to build manifold vacuum. It'll start out at say 0 or 5 Hg and slowly rise on up as the revs get up there.

Is this a normal thing or is there something I should do to stop it?

-5150 :bandit:

[jteuton]

sounds normal to me.....as the engine request more air the vacuum start to build.....i don't know anybody else with any ideas?

[jteuton]

actually i think it depends where it is measured.......and i think i'm backwards. there is vacuum for external devices at idle but as the pedal as pressed you get closer to atmospheric pressure and you lose vaccum

[A20A1]

hmm looks to me like you need a bigger throttle body... and a performance intake manifold. If you're building vacuum and you are meausuring it from the manifold then that means your engine want's more air then the TB and Intake Manifold are willing to give. First off make sure you have an intake... make sure the intake pipe is mandrel bent and is larger then the stock diameter then make sure you have a large filter since small fillters could also restrict air flow as engine speeds increase.

[A20A1]

oh wait... one simple thing is to make sure your throttle cable is tight... actually just make sure that when the pedal is pressed to the floor... the TB butterfly is open all the way

[A20A1]

bump