In anticipation of my car getting the ugr paxton treatment, I installed a boost/vac gauge in the car tonight. It is a mechanical gauge which I tapped into the MAP sensor line at the rear of the block of the passenger side of the intake manifold. Tator advised me that it was as good a place as any to tap into the motor. When I started the car the gauge moved to about -12 or -13 on the vac side which I expected to see but when I hit the gas the pointer moved up towards 0 but fell sharply to -20 or so when I held the rpms up at 3k or so steady. I figured it would stay close to 0 while the car was being rev'd but it didn't. Never expected that. I suppose that's normal but I really never had a boost gauge installed in a car before the blower was done so because the car is running perfectly, I am thinking it is ok. Does anyone know how it should react pressure wise in a vehicle not running a blower (yet). Josh
Only other car I had one on was an '03 cobra which of course was supercharged and the gauge did read in the vac side at idle but holding the rpms up like I did tonight I believe would be reading close to 0 on the gauge. I suppose that even though boost wasnt being pushed into the motor at only 3k on the cobra that it was creating more of a positive pressure number by having the blower on the car.
thanks Chris. Nice talking to you today buddy. We definitely need to meet up for some street smack downs next time i'm in your neck of the woods. Josh.
At 800 rpms at idle you want to be around the 20-24 inhg at idle. That mean your engine is getting good vacume. Anything less then this at idle means you got a possible vacume leak somewhere.
when you go full throttle it will go towards 0 inhg for n/a cars. This basically means the engine has fully inhaled. Boosted cars will obviously build pressure psi more then the engine can inhale.
At 800 rpms at idle you want to be around the 20-24 inhg at idle. That mean your engine is getting good vacume. Anything less then this at idle means you got a possible vacume leak somewhere.
when you go full throttle it will go towards 0 inhg for n/a cars. This basically means the engine has fully inhaled. Boosted cars will obviously build pressure psi more then the engine can inhale.
No way an engine with a Viper sized cam is going to pull that much vacuum at idle.
No way an engine with a Viper sized cam is going to pull that much vacuum at idle.
You seem to be correct as my car COLD at idle was pulling 12-13 of vac. at idle. Hitting the gas lightly made it pull closer to 20 of vac on the gauge.
You seem to be correct as my car COLD at idle was pulling 12-13 of vac. at idle. Hitting the gas lightly made it pull closer to 20 of vac on the gauge.
MY viper with the Striker street cam pulls 10 in/hg at idle. (idle set to 800rpm)
Linear Mode
