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Old 01-06-2008, 01:58 PM   #1
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Default Tell me about superchargers

I recently bought a 96 SSEi and this is the first car I have owned with a */c. I work on an ambulance with a turbo diesel and have some understanding of turbos, and I thought that the only difference in the two was that the */c is belt driven off the motor, and the turbo is air driven off the exhaust. But I am finding that my boost gauge shows negative to no pressure when I am driving casually and only goes to positive pressure when I get on the gas hard. Also why does the boost "step up" as the tranny up shifts and actually drops RPM'*. I am used to a turbo where you have more boost with higher revs, and it drops boost as you up shift.
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Old 01-06-2008, 02:03 PM   #2
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Sounds like your supercharger is working just fine.

I'll move this to the Forced Induction section so that it gets better exposure.
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Old 01-06-2008, 02:12 PM   #3
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Sounds pretty normal. How much does it step?
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Old 01-06-2008, 02:23 PM   #4
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It goes up about 2-3 psi when up shifting
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Old 01-06-2008, 02:27 PM   #5
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Under part throttle that'* about right. WOT might show a little boost rise with upper RPMs, but not much.
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Old 01-06-2008, 02:37 PM   #6
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So how much boost do these things put out at peek? Are you getting any benefit from the */C when it is in the negitive side?
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Old 01-06-2008, 02:40 PM   #7
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I think 7 to 9 psi is norm on a Series II. You don't get any SC benefit when it'* under vacuum. It'* a function of the wastegate. Without it, you'd have boost at all times which would be murder on a gasoline engine'* MPGs.
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Old 01-06-2008, 02:51 PM   #8
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Anybody remember that animation that shows the supercharger and its wastegate operating under different engine loads?
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Old 01-06-2008, 03:20 PM   #9
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Quote:
Originally Posted by dillcc
Anybody remember that animation that shows the supercharger and its wastegate operating under different engine loads?
that was in this coblat thread

http://www.bonnevilleclub.com/forum/...ght=cobalt+gen
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Old 01-06-2008, 05:00 PM   #10
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Thanks. Yeah that'* the jist of it. Not the same motor, but at least the same style of supercharger.
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