Negative Boost Gauge Reading?

[JungleJim]

I've got an Impulse turbo 2008 Nytro with the race kit and Boost-it on it and my Boost gauge will be at around -5 at idle and dip down to -10 as the motor starts to rev up and engage. It eventually will climb up to the 15 lbs I'm targeting to ride at now. I've heard varying opinions on why it dips down to -10 and was wondering is this normal? Something to be concerned about? Thanks!

 

[TABSTER]

I've got an Impulse turbo 2008 Nytro with the race kit and Boost-it on it and my Boost gauge will be at around -5 at idle and dip down to -10 as the motor starts to rev up and engage. It eventually will climb up to the 15 lbs I'm targeting to ride at now. I've heard varying opinions on why it dips down to -10 and was wondering is this normal? Something to be concerned about? Thanks!

Its Normal, all sleds are naturally aspirated and will read negitive until you start making boost.

 

[Bnorth]

It's called vacuum, all motors pull vacuum but only boosted motors will go from vacuum to positive pressure.

 

[4x4racing]

I have the same on my 09 and only see -3 at the most at idle or no load it will read -10 once and a while but that's just the pos gauge getting wet once it drys out it reads -3 to 22 again

 

[SNAFU]

Yes, normal. Vacuum initially until turbo is spinning fast enough to generate positive pressure in the intake. Mine reads the same. Does your gauge read zero when the sled is off? I zero'd mine at home and it will read some positive pressure in the staging areas which are at lower elevation. Once I get up higher it usually reads zero, or close to it.

 

[JungleJim]

It reads zero when shut off, about - 5 at idle then dips down to -10 when motor starts to acclerate. Thanks guys for the input as this certainly makes sense.

 

[samsquatch47]

This is completely normal. My race gas impulse Nytro reads the exact same vacuum readings at idle and at low load conditions.

 

[Octanee]

My sled, its got one of those expensive autometer boost gauges, liquid filled, but it reads +3 or so at 3000 ft, and still the same at 6000 ft, of course my group just jokes and say, well hey it just means your ready to go all the time, building boost when sleds off!

but i had tested it with some air systems and found it to end up reading spot on anyways......

 

[Redturbo]

On liquid filled gauges, there is a bleed screw on the gauge. Trying just loosing the screw, it should go back to 0.

 

[senorjeem]

Negative Boost!! That sucks!


Hahahaha.........I'm here all week folks. Thank you very much!

 

[Octanee]

On liquid filled gauges, there is a bleed screw on the gauge. Trying just loosing the screw, it should go back to 0.

i tried that, it did not :\ but it "appears" to read alright comparing to other air pressure systems sooo who knows

 

[Allanhanes]

I just put a liquid filled guage on that reads 0 to 30lbs and the numbers are larger makin them easier to see as well. in my own opnion you dont need to see vacume on a turbo sled you only wanna see the boost thats thats hp.

 

[TABSTER]