2lbs of boost??
09-08-2003, 10:42 AM
#1
Burning Brakes
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2lbs of boost??
ok i put in a boost gauge and i have a vac line going from the intercooler pipe straight to the waste gate and the boost gauge shows 2 pounds of boost. 15 vac at idle and 20 vac at about 1500 or so in nuetral. is my boost gauge off?or is it actually only have 2lbs?
09-08-2003, 11:29 AM
#2
Rennlist Member
How does the car feel, powerwise? If youre only making a couple psi, it will be slow.
>"vac line going from the intercooler pipe straight to the waste gate"
From the banjo bolt connection to the waste gate, bypassing the cycling valve and no mechanical pressure relief valve? If so, then you wont be holding any boost pressure because the waste gate will open anytime you start building any boost.
>"vac line going from the intercooler pipe straight to the waste gate"
From the banjo bolt connection to the waste gate, bypassing the cycling valve and no mechanical pressure relief valve? If so, then you wont be holding any boost pressure because the waste gate will open anytime you start building any boost.
09-08-2003, 12:23 PM
#3
Burning Brakes
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yea straight from the banjo bolt to the wastegate, bypassing everything
i thoguht it should hold atleast 4 or 5 pounds just because of the spring in the waste gate. I was waiting for my boost gauge so i could hook up my boost control and configure it but i'm not sure about the accuracy of the boost gauge so i dont want to set boost using it. if it sound right for this type of set up that i only have 2 lbs then i'll just set it up. the car doesn't feel SLOW, i put the turbo motor into my na and it feels maybe faster than before?maybe the same....its hard to tell, didn't drive the car for a few weeks while i was putting the motor in
i thoguht it should hold atleast 4 or 5 pounds just because of the spring in the waste gate. I was waiting for my boost gauge so i could hook up my boost control and configure it but i'm not sure about the accuracy of the boost gauge so i dont want to set boost using it. if it sound right for this type of set up that i only have 2 lbs then i'll just set it up. the car doesn't feel SLOW, i put the turbo motor into my na and it feels maybe faster than before?maybe the same....its hard to tell, didn't drive the car for a few weeks while i was putting the motor in
09-08-2003, 12:49 PM
#4
Rennlist Member
I think the default safe mode for the boost is 1.3 bar (which is around 4psi), but thats when the KLR has left the cycling valve open. So the air flow through the banjo bolt/line to the cycling valve down to the waste gate is not as direct and will be slightly more restrictive than just a straight line to the waste gate. But that should just slow the WG reaction time, not change the steady state (just like using a jetted banjo bolt with APE chips-you get a spike in boost pressure but it drops off).
Regardless, its hard to say exactly how much boost it will run with the waste gate open. I would think that would depend on too many factors to be a good test for the accuracy of a boost gage.
Regardless, its hard to say exactly how much boost it will run with the waste gate open. I would think that would depend on too many factors to be a good test for the accuracy of a boost gage.
09-08-2003, 01:58 PM
#6
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1.013 bar = 14.696psi = 1.0 atm at sea level.
The turbo instrument cluster gage reads absolute pressure, so it includes basic atmospheric pressure. The factory manuals and specs are all written in this format. So the peak boost is shown as 1.75 bar, safe mode 1.3 bar, etc. In this way, vacuum is still shown as a positive number.
Your aftermarket gage is reading gage pressure, the difference between the manifold pressure and atmospheric. Vacuum would be a negative number. So without getting into the semantics of altitude and temp correction factors, basically subtract off 1 bar from the factory spec/gage. So peak boost would be about 0.75 bar gage, safe mode 0.3 bar etc, then convert to psi.
My mistake for quoting an absolute pressure (1.3 bar) equating to a gage pressure (4psi). To clarify: 0.3 bar = 4.35 psi
The turbo instrument cluster gage reads absolute pressure, so it includes basic atmospheric pressure. The factory manuals and specs are all written in this format. So the peak boost is shown as 1.75 bar, safe mode 1.3 bar, etc. In this way, vacuum is still shown as a positive number.
Your aftermarket gage is reading gage pressure, the difference between the manifold pressure and atmospheric. Vacuum would be a negative number. So without getting into the semantics of altitude and temp correction factors, basically subtract off 1 bar from the factory spec/gage. So peak boost would be about 0.75 bar gage, safe mode 0.3 bar etc, then convert to psi.
My mistake for quoting an absolute pressure (1.3 bar) equating to a gage pressure (4psi). To clarify: 0.3 bar = 4.35 psi