after I shift my vaccum can usually reach 30mm Hg, I was just wondering if that was normal

-87 TII
-blitz BOV
-Defi boost and AF gauges

thanks

 

Your units are wrong. 30mmHg vacuum is nothing. I assume you mean 30inHg (which is about 760mmHg). That's also impossible to reach, because that is zero absolute pressure, i.e. a complete vacuum. If your gauge really does get down to 30inHg, it's not reading right.

 

I get about 22inHg

 

Right after you shift wouldnt the release of all the pressure via the aftermarket bov drop the vaccum to almost complete vaccum?

 

A BOV cannot create vacuum, it only releases boost pressure. On a car the only thing that can create vacuum is a throttled engine, and it certainly cannot get anywhere near absolute zero pressure. Low 20's (inHg) is about as low as you'll ever see.

 

i run about 12 vac just idelin...but all my buds run like 20 vac and they have eclipses and talons. i have only catback exhust done to my car, is that normal?

 

i do bout 15 vacuum at idle and 20 after shifts

 

yeah, I show like 13 at idle. maybe kinda low because of my aftermarket intercooler?

 

when your engine is under deceleration, you will see higher vac. When engine braking into a corner, my boost gauge drops almost to 30.

12-15 vac (on a sport comp boost/vac gauge) is great at idle for our cars.... you start getting below 10 Vac. at idle and you may have apex seal problems. (or a vac leak).

Eclipses and Talons are different animals, its hard to compare a piston engine to a rotary.. so don't worry about what they run.

 

oh, I thought we were supposed to be at 15 at least.

 

thx, i didnt know if piston enginens acted difernet ( vacum wise).

 

yeah I meant 30in Hg sorry about that but at idle I have 20 in so I guess that means there's a leak somewhere?

 

Whats with all you people putting your vac gauges before the throttle? :-p

 

what? putting the gauge before the throttle shows NO vac.



having a leak would show less vacuum, right?

 

No it means your gauge is broken. You would need a very tight engine to get 20inHg at idle and getting 30inHg anytime is physically impossible. It cannot be done in this universe!

Check your gauge against another one if you can, coz it's not reading right.

 

Ancient Thread time (Ignore my last post in this thread, major typo)

The lowest I ever see is when I am engine breaking down a steep hill I hit just over 26inHG
Cruse at 18inHG and go up hills at 11inHG. WOT at 0