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Author Topic: What boost should I be getting?  (Read 3565 times)

Offline JonnieG40

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What boost should I be getting?
« on: December 09, 2009, 10:15:13 pm »
Ive got a 65mm pully on my charger and was wondering what boost I should be getting? I think ive seen it at 0.7 Bar near redline. Should it be more though? Im running twin v belts so could it be slipping at high RPM?

John
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Offline hayesey

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Re: What boost should I be getting?
« Reply #1 on: December 09, 2009, 10:59:20 pm »
the belts are most likely slipping. You should be getting more like 0.9 - 1.1 bar depending on the spec of the engine, a longer duration cam, gt inlet or ported/big valve head will decrease the boost pressure you see in the inlet manifold slightly.
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Offline PeteG40

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Re: What boost should I be getting?
« Reply #2 on: December 10, 2009, 09:16:12 am »
depending on yr charger too... ported ones push out more air
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Offline JonnieG40

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Re: What boost should I be getting?
« Reply #3 on: December 10, 2009, 01:48:30 pm »
my charger has had the Jabba R1 rebuild not too long ago
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Offline wozzaG40

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Re: What boost should I be getting?
« Reply #4 on: December 11, 2009, 08:16:48 am »
Well you are definetly loosing power then, a toothed pulley system would solve this issue however i am not sure where you can get one from anymore. No doubt Pete will have some ideas.

Belt dressing would help to reduce the slip for the mean time though.
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Offline JonnieG40

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Re: What boost should I be getting?
« Reply #5 on: December 11, 2009, 02:39:22 pm »
what is belt dressing? Im thinking about selling my G soon anyway but it would be nice to get the power up a bit before it goes
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Offline G40supercharged

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Re: What boost should I be getting?
« Reply #6 on: December 11, 2009, 06:24:22 pm »
An R1 charger with 65mm pulley should make 0.7 bar by about 3000rpm, peaking at around 1 bar. The belt slip is only an issue at high rpm. Do you have an induction kit? An unmodified stock airbox is very restrictive and will limit boost to 0.7/0.8 bar (as I found out when I first put a smaller pulley on).
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Offline JonnieG40

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Re: What boost should I be getting?
« Reply #7 on: December 11, 2009, 07:48:21 pm »
yeh ive got the jabba sport induction kit with heat sheild. On boost I cant hear any escaping air at all. Could it be the butterfly valve that closes to direct boost into the throttle?
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Offline hayesey

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Re: What boost should I be getting?
« Reply #8 on: December 11, 2009, 08:08:12 pm »
I'd still suspect the belts slipping before anything else.  How old are they?
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Offline JonnieG40

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Re: What boost should I be getting?
« Reply #9 on: December 12, 2009, 08:15:41 pm »
Yeh, Ive just looked through my huge folder of history and the only documentation I can find about the V belts being changed was from 2002....7 years ago. So its most probably the belts then.
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