Boost Gauge Questions

SleeperGT · 09-20-2003, 04:33 PM

I just had the AutoMeter Lunar gauge cluster installed, along with a boost and fuel pressure pillar gauges. Question I have concerns the Boost gauge. What exactly does the vacuum side of the gauge mean? When I'm just motoring around town under moderate throttle, it ranges from 10 to 5 or so. When I hammer it in 1st or second gear I might see 0, maybe 1 or 2 on the Pressure. It seems I really only get into the Pressure side of the gauge when I really hammer it in 3rd gear and I'm really at high speed I'm registering up to 8 psi at this point, which is what I expected. And it is a very gradual build up to the 8 pounds. Can someone explain the progression from the VAC side of the gauge through to the Pressure side of gauge? Thanks!

jonnyk · 09-30-2003, 09:05 AM

Vacuum is when your throttle blade is mostly closed, the outside air can't get in and the engine is still spinning, trying to suck it in, so it forms a vacuum. Once you stomp on the gas the throttle blade opens, air rushes in and fills the vacuum, and your manifold will be close to ambient air pressure (the 0 marker). Once the blower starts to work, up goes the boost.

BilLster · 09-30-2003, 10:12 AM

this is normal with a vortech style blower they dont make boost till high Rpm .

Vacum is the motor trying to suck air in boost is the blower forcing air in.

jonnyk explained it better than i could.

SleeperGT · 10-01-2003, 12:39 PM

Thanks guys! Very helpful.

09-20-2003, 04:33 PM	#1
SleeperGT Registered Member Join Date: Sep 2002 Location: Ponte Vedra Beach, FL Posts: 122	Boost Gauge Questions I just had the AutoMeter Lunar gauge cluster installed, along with a boost and fuel pressure pillar gauges. Question I have concerns the Boost gauge. What exactly does the vacuum side of the gauge mean? When I'm just motoring around town under moderate throttle, it ranges from 10 to 5 or so. When I hammer it in 1st or second gear I might see 0, maybe 1 or 2 on the Pressure. It seems I really only get into the Pressure side of the gauge when I really hammer it in 3rd gear and I'm really at high speed I'm registering up to 8 psi at this point, which is what I expected. And it is a very gradual build up to the 8 pounds. Can someone explain the progression from the VAC side of the gauge through to the Pressure side of gauge? Thanks! __________________ '00 GT 5-spd Vortech S-Trim 3.1" Pulley Paxton Air-to-Air Aftercooler 90 mm MAS 42 lb injectors Cobra Fuel Pump 70 mm AccuFab Throttlebody C & L Intake Plenum 2 1/2" X-pipes Anderson PowerPipe MagnaFlow Mufflers Diablo Custom Chip 3.73's Steeda Lower Control Arms 358 rwhp (Mustang Dyno) New Track Times Coming Soon

09-30-2003, 09:05 AM	#2
jonnyk Being stroked is great Join Date: Oct 1998 Location: Alberta, Canada Posts: 772	Vacuum is when your throttle blade is mostly closed, the outside air can't get in and the engine is still spinning, trying to suck it in, so it forms a vacuum. Once you stomp on the gas the throttle blade opens, air rushes in and fills the vacuum, and your manifold will be close to ambient air pressure (the 0 marker). Once the blower starts to work, up goes the boost. __________________ Novi 2000 now spinning off the snout of the 331... Mods Pics

09-30-2003, 10:12 AM	#3
BilLster Registered Member Join Date: Oct 2000 Location: Ontario canada Posts: 446	this is normal with a vortech style blower they dont make boost till high Rpm . Vacum is the motor trying to suck air in boost is the blower forcing air in. jonnyk explained it better than i could. __________________ 89 with 331 t3'/t4 hybrids. upr Suspention worked out finnaly . 9.89 144 mph .

10-01-2003, 12:39 PM	#4
SleeperGT Registered Member Join Date: Sep 2002 Location: Ponte Vedra Beach, FL Posts: 122	Thanks guys! Very helpful. __________________ '00 GT 5-spd Vortech S-Trim 3.1" Pulley Paxton Air-to-Air Aftercooler 90 mm MAS 42 lb injectors Cobra Fuel Pump 70 mm AccuFab Throttlebody C & L Intake Plenum 2 1/2" X-pipes Anderson PowerPipe MagnaFlow Mufflers Diablo Custom Chip 3.73's Steeda Lower Control Arms 358 rwhp (Mustang Dyno) New Track Times Coming Soon

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