Author Topic: boost  (Read 3394 times)

Offline GTG40

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boost
« on: June 23, 2008, 02:23:41 pm »
Who's got a boost guage on there G what bar presure you getting?

i think i have a boost leak

my charger has been stage 4 by jabba and has a 68mm pully
what pressure should i be getting?

Offline PeteG40

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Re: boost
« Reply #1 on: June 23, 2008, 02:46:50 pm »
standard with standard pulley - about 0.5/0.6bar
max ported (full blend etc) with 65mm pulley - about 1.1 bar

yours should be inbetween i'd say about 0.8?

Offline GTG40

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Re: Re: boost
« Reply #2 on: June 23, 2008, 02:56:28 pm »
thanks. i'm going to buy a boost guage now and test it
« Last Edit: June 23, 2008, 03:00:02 pm by GTG40 »

Offline bushyg40

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Re: Re: Re: boost
« Reply #3 on: June 23, 2008, 04:34:03 pm »
but if u think about it boost gauge is a measure of resistance if no rescistance u wouldnt have any reading at all and mine was 15psi
« Last Edit: June 24, 2008, 01:46:07 pm by bushyg40 »

Offline dannyb.G40

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Re: Re: Re: Re: boost
« Reply #4 on: June 23, 2008, 08:08:16 pm »
i saw a chart somewhere with a list of modifications and expected boost and for the life of me cant think where i saw it. i think it was probably on the CP forum but i cant remember

anyone else seen it?

Offline PeteG40

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Re: Re: Re: Re: Re: boost
« Reply #5 on: June 23, 2008, 08:28:17 pm »
there are quite a few variables  - like gt inlet or big valve head which would make the car faster but with less boost

Offline G-spot

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Re: Re: Re: Re: Re: Re: boost
« Reply #6 on: June 23, 2008, 10:44:24 pm »
[quote pid=1887 author=peteg40 date=1214249297]there are quite a few variables  - like gt inlet or big valve head which would make the car faster but with less boost[/quote]

This is true, its easy to achieve a high boost back pressure(cos thats what it is) when the air has nowhere to go(ie standard spec engine), once you start to play with other components such as manifolds/cams/heads/valves/throttle bodies/intercoolers/pistons etc.... then you can see that back pressure within the intake system be reduced, this does not necessarly mean a loss in performance,but that your engine(system) is moving the air more effeciently when producing the power.  Don't forget that the more boost (backpressure) you have then the greater load the charger is putting on the engine and therefore more energy is required to turn it.
It all about achieving the optimum from many varibles.

Or am I just talking dribble................... :/

Offline giorgio

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Re: Re: Re: Re: Re: Re: Re: boost
« Reply #7 on: June 25, 2008, 09:11:04 pm »
[quote pid=1895 author=G-spot date=1214257464]
Or am I just talking dribble................... :/[/quote]

No as far as I am concerned your right. Steve PSD said a well set up Eaton should produce 10psi with a standard PY with an eaton can see anything upto 18psi.

I also spoke to JP of JNL Racing about this and he said the same thing - that a boost gauge measures pressure in the inlet manifold, not the 'boost' being produced. I suppose a more useful useful gauge is one that displays CFM
« Last Edit: June 25, 2008, 09:11:24 pm by giorgio »