boost gauge reading 20 lbs vaccum? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

ncrk · 02-10-2008, 09:22 PM

i installed a new autometer boost gauge and i drove my car for the first time and it was reading between 10 and 20lbs of vaccum...
if it helps, i have the t25 turbo that comes with a redtop sr20
why is it doing thatt??

Kouki · 02-10-2008, 10:21 PM

If you're just cruising the gauge is going to read vac, if you put it to the floor you should see it hit full boost between 2900-3200 rpm. At idle it will probably read somwhere around 20-25psi vac, because there is no load on the engine.

sd8ted · 02-11-2008, 12:09 AM

What you are seeing is completely normal. My car idles at ~21psi vacuum and unless I'm over 1/4 throttle it will stay on the vacuum side. If you are saying that you are full throttle and the gauge won't come out of vacuum then theres either a problem with the line to the gauge or the gauge itself.

louisdaboois · 02-11-2008, 01:18 AM

its actually mmHg of vacuum. which 25mmHg is about 0.5psi if my asian genes serve my calculations correctly.

02-10-2008, 09:22 PM	#1
ncrk Users Awaiting Email Confirmation Join Date: Oct 2007 Location: SoCal Posts: 38 Trader Rating: (0) Feedback Score: 0 reviews	boost gauge reading 20 lbs vaccum? i installed a new autometer boost gauge and i drove my car for the first time and it was reading between 10 and 20lbs of vaccum... if it helps, i have the t25 turbo that comes with a redtop sr20 why is it doing thatt??

02-10-2008, 10:21 PM	#2
Kouki Zilvia Addict Join Date: Feb 2005 Location: Nebraska Age: 40 Posts: 727 Trader Rating: (3) Feedback Score: 3 reviews	If you're just cruising the gauge is going to read vac, if you put it to the floor you should see it hit full boost between 2900-3200 rpm. At idle it will probably read somwhere around 20-25psi vac, because there is no load on the engine.

02-11-2008, 12:09 AM	#3
sd8ted Leaky Injector Join Date: Nov 2005 Location: Greenville, SC Posts: 72 Trader Rating: (0) Feedback Score: 0 reviews	What you are seeing is completely normal. My car idles at ~21psi vacuum and unless I'm over 1/4 throttle it will stay on the vacuum side. If you are saying that you are full throttle and the gauge won't come out of vacuum then theres either a problem with the line to the gauge or the gauge itself.

02-11-2008, 01:18 AM	#4
louisdaboois Zilvia Addict Join Date: Dec 2006 Location: LA, CA Age: 36 Posts: 851 Trader Rating: (28) Feedback Score: 28 reviews	its actually mmHg of vacuum. which 25mmHg is about 0.5psi if my asian genes serve my calculations correctly.