| Author | Topic |
|---|
Registered:
March 2004
|
|
boost questions
|
Tue, 27 July 2004 20:59
|
 |
|
I am seeing low boost on the supercharger I installed on my engine. Im just wondering if a supercharger setup is rated at 6psi of boost is this dictated by the engine? these kits(powerdyne) are for V8's with moderated compression ratio. I have a 2.1ltr 7.4:1 CR and I am only seeing 2lbs of boost. I have no leaks and the blower is moving air. could my engine be the problem?
|
|
|
Toymods Vice President
Location:
Sydney
Registered:
May 2002
|
|
Re: boost questions
|
Tue, 27 July 2004 23:36
|
|
The boost pressure of an engine running a positive displacement supercharger is a function of how much air the engine can consume compared to how much air the supercharger can move.
The supercharger displaces a fixed amount of air per revolution, ignoring sealing and efficiency revs, so we obviously have to have the charger moving more air than the engine could normally consume to be able to get e possitive pressure in the manifold.
That's my rootes blower basics for today. What drive ratio is the blower running at, compare it to the 1GGZE and see if it's lower than the 1G then logically you'd expect it to produce less boost, although the 18RG isn't as efficient as the 1G.
|
|
|
Registered:
March 2004
|
|
Re: boost questions
|
Tue, 27 July 2004 23:48
|
|
|
That is a great answer!! I have a set of pulleys that are exactly what came stock on the 1ggze. and the engine is only getting 3.5lbs. so does this mean the 18rg can consume alot of air? it must flow too much.
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: boost questions
|
Wed, 28 July 2004 00:17
|
|
No, an 8-valve 18R-G is unlikely to out-flow a 24-valve 1G-GZE. My guess is you have an air leak somewhere, or your SC14 is worn out.
|
|
|
Toymods Vice President
Location:
Sydney
Registered:
May 2002
|
|
Re: boost questions
|
Wed, 28 July 2004 00:23
|
|
It is possible that you have too much overlap on the cams and you are blowing intake charge out the exhaust. Have the cams you're running been degreed to make sure they are in the right location. I ask because I seem to remember your signature saying you had 304 degree cams at one stage.
Other than that possibility I'd be looking for a leak.
|
|
|
Location:
Brisbane
Registered:
May 2002
|
|
Re: boost questions
|
Wed, 28 July 2004 00:28
|
|
These exact issues were covered in the last thread... I'm not sure why we're going over it all again now? Anyway he claims he has stock cams in it now, but you're right, the cam timing could be out. Check it and then double-check it!
|
|
|
