On my setup I don't have a waste gate. I have a bypass that is supposed to vent back into the filter. My bypass is alot slower than a blow off and is frustrating to hear at times, lol. If the throttle is let out, the bypass is conected to the trucks vacuum. To prevent compressed air coming from the blower, after the throttle is reduced, the bypass releases the pressure.

 

the amount of boost measured is stated as being a certain PSI, but technically it is the amount of pressure in excess of the current natural air pressure.

blown, where in your system is the boost measured? at the manifold, or closer to the blower?

 

Directly at the manifold. I wanted it after the alky system to monitor because I'm changing the temp of the air. I'm not sure its enough to matter, just wanted to be as accurate as possible.

 

In sledding, the general rule of thumb is you lose 3% per thousand feet. If you have a snowmobile that produces 150hp at sea level, it is making approximately 117hp at 8000ft. This is two strokes I am talking about, but the density of air lost is still the 3% per thousand. But if you are running a turbo sled (the new 4 strokes) you maintain almost full horse power at that same elevation. These sleds are the new Yamaha's and Skidoo's in the 1000cc to 1200cc range and are making up to 400hp reliably. Now take a 600lb machine with 400hp and you have a very insane ride.

 

as ive always understood it, that method is best for tuning, but there is also the consideration that when youre making say, 14psi at the manifold, the turbo or supercharger is working harder because of the boost loss throughout the system. i dont know about blowers, but with the turbos you can overwork your turbo and cause early death to the turbo...espcially these guys running these rear-diff located turbos...the boost loss has to be extensive, causing the turbo to do a tremendous amount of work.

 

The boost gauge is a stand alone, the only system I have that reads the boost is the split second that is for controlling alchohol injection. The supercharger is belt driven and boost is controlled by switching pulley size. Right now I'm on the 3.25" pulley that delivers 13-14psi of boost at high RPM. I honestly don't know how boost is controlled through turbos. If you have suggestions for extending the life of the blower, I'm open to them.

 

so, that 13-14, is that what is advertised by the supercharger manufacturer, or is that what you are measuring with the split second?

turbo boost pressure is controlled by the waste gate. much in the same way that a boost gauge monitors pressure, the waste gate is connected to a vacuum source typically on or near the turbo housing, and when the turbo creates enough pressure, the waste gate opens to bleed out what pressure is being made in excess of the desired amount. the way that you up you boost is with something like a manual boost controller. this goes inline of the vacuum hose connected to the waste gate actuator, and basically interferes with the pressure going to the WGA. with the MBC all the way closed, the WGA doesnt have anything pulling on it, so the turbo would literally provide as much boost as possible at its peak RPM...nicer ones have ***** to tell you how much youre dialing to, but ive seen people make their own from stuff at home depot and it works just as well...you just have to be careful about dialing them in. lots of people think that all the way closed with an MBC is how to start off, then they drive the car and rather than making no boost, theyre making enormous boost and they screw up their engines...

 

I can monitor my boost on the split second readout, I've even came up for a HUD for it that I will eventually mount by the rear view mirror. For now I still use analog gauges. Below I have added a youtube video of the blower startup. On the left is my A/F gauge on the right boost.

I have a vacuum line that is attached to the bypass much the same way as you have described the waste gate BOV.

As far as the Paxton blower drive pulleys, they advertised them back in 2002 as 14psi pulleys etc. Because every setup is slightly differet i.e. Dakota, Durango, Ram Jeep etc and everyone is seeing slightly different boost amounts, they just advertise them as 3.25 pulleys now.

3.5" Basic 10-12 psi
3".25" 13-14 Psi
3" 14-16spi
2.75" Smallest drive pulley 16+ psi

Richie is the only person I know running a 3" and he see's 16psi on his setup as long as he doesn't get belt slip.

http://www.youtube.com/watch?v=uRf9eJNevSU

 

This is what I need for my launch, but I would be affraid I would mess it up.

 

im not familiar enough with blower setups to know whats available to help with your problem...it seems to me that you should be able to drag out that bypass...