whats everyones vacuum readings at idle?
i have an autometer gauge and im using a vacuum hose instead of the teflon because i kinked that thing.

I have a slight hissing from the npt fitting on the gauge, but i dont' know how because i used teflon tape on it!!!

my readings are at 15psi at idle; this would even goto 20psi when im actually at a light. ??? i dont' know i think i gotta check all my hoses and stuff...

does a slight vacuum leak effect anything because i reach 19.5 psi boost NO problem!

 

Blackwood! I am right in Marlton.

Hard to say. IF you hear it leaking at idle then you would have a leak, but if it reads boost properly then it can't be too bad.
It sounds like the leak is minor. Average vacuum is only around 17 in Hg. I have an autometer boost gauge but it doesn't read vacuum. I have a HKS EVC V and that is where I am getting my reading from. I've also had a vacuum gauge on the car at idle before I had the EVC and got the same reading.

 

Have you ever tried to put a boost gauge in Normally Aspirated car?. i did once in a Lancer 4G93 and showed vacuum readings of 23psi at idle (ave.). That´s normal because engine is sucking air.
At idle its supposed that turbo is not spooling so much air so it is going into the engine mostly because it´s being sucked.
My readings at idle are -19psi, -20psi. I´ve never got -17in Hg (8psi) at idle.

 

I use a Autometer gauge and my readings are pretty much the same as yours.

 

when you guys are driving the car, and let off and blow off...how far does your vacuum dip?? mine dips to like -25, but settles back up to 20 at idle or a light after it blows off the pressure. I also am using autometer gauges...Phantom series to be exact. I like the look of em.

 

what about in the morning in the cold days?
im around 12psi vac.

im just paranoid cause its lower than what im used too.

 

yes thats about right when its cold first thing in the morn.

 

Don't worry about running too much vaccum, at idle anywhere from 15-20 (on the negative side) is fine. You will see less vaccum at startup because the engine is idling faster in order to warm up and pulling a bit more air into the system, same thing if you turn your A/C on.

 

Mine is in the -18psi, -19psi range at the morning and does the same thing as 93civ stated.
The question is how long takes to reach the 0psi point...Mine spools is very, very quick. Just with a ligh throttle depress i´m in the 0psi ready to be launched.
Going in 3rd gear and making a gear shift the pressure goes down to the -5psi, -8psi range but it depends on each blow off setting.

 

My boost vac/gauge is around 18-22 on an autometer....you are fine. At times it does vary as mentioned earlier.

 

I have an Autometer gage. I get -14inHg in the morning, -15inHG at idle with the car warm, and -18inHg if I jump off the gas.

BTW, Bom's Evo do you mean you are reading -15inHg and -20inHg and not -15psi and -20psi? (thats huge difference) I willing to bet your gage reads in inHg for vacuum.

-15 psi = -30.5 inHg

 

my bad. i mean -15inHG

 

Odd you guys with autometers are all getting in the -15psi area. It's normal for people with the Blitz DTT to be getting -0.7 bar (~10psi) at idle. I've seen it as low as -0.9 bar when engine braking.

Maybe different gauges are calibrated a lot differently in the vacuum range. IF they're calibrated at all.

 

I'm choosing between the two Autometer Sport-Comp mechanical boost gauges, one with vac (goes to 30 PSI) and one without (goes to 35 PSI and the one I prefer). I also have the Blitz DTT, which apparently has a digital vac gauge. Is there any reason, I'd need to have the mechanical vac. gauge (i.e. to better see changes)?