Anyone want to help me?...Please.

I can't seem to find a manifold vacuum chart for the S4/S5's anywhere. I really really need to know what I should expect from idle to no vacumm. I currently do not have running/normally running engines to test myself, so I'm stuck.

 

15 to 18 psi is good vacum numbers for a strong running non ported 13bt

 

Thanks!

Do you know what the vacumm would be off idle at various rpms as well? I am working on a vacuum-controlled switch circuit and need to plot a rough curve of the vacuum in say, 500 rpm increments. That would be for vacuum that has "balanced" under load at specific rpms. Mazda has to have a chart out there somewhere already. I really hate asking for someone to actually hook up a gauge and go driving around...

 

Yeah, my new engine pulled about 20 in hg at idle.

 

well it varies with throttle position. idle @0 throttle, an na should be around -18psi, anything over 70% throttle is going to be near 0psi no matter what the rpm is (we actually saw 1-2psi boost on an na with the haltech)

 

There are so many things that affect that reading. I love how no one mentions ign timing.

 

Good point 1Revvin7.

I should be alright starting with stock numbers, and hopefully I'll have enough leeway when it comes to adjusting the switch for my setup. I know I'm probably trying to factor in to many things for this switch, but I really want to be on the safe side. As long as vacuum is below -12/-10psi at 20-30% throttle it should be fine.





Thanks guys!