When does useful boost come on in a standard Comptech SC install?
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From: Ottawa
When does useful boost come on in a standard Comptech SC install?
I guess the subject says it all... just curious as to when useful boost starts to be made with the standard Comptech SC install. I guess that leads to another question - does anyone know the rough (x lbs of boost = ~ y% gain in hp) equation in this particular application?
Thanks,
...Andrew
Thanks,
...Andrew
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From: Sydney
Depends what you mean by useful. The boost delivery is pretty linear. 0 at 0RPM, 5.4psi at 9000 (from an early dyno of my S with Comptech non-AC). Draw a straight line between them.
IMHO you could feel the SC from about 5000rpm and then it went ballistic from there. I'm now running a smaller pulley and better engine management so it's very apparent from about 4000.
IMHO you could feel the SC from about 5000rpm and then it went ballistic from there. I'm now running a smaller pulley and better engine management so it's very apparent from about 4000.
Joined: Jan 2003
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From: Used Jersey
full boost isn't until redline. I get 5 psi in 1st and 2nd gear redline and 6psi in 3rd and 4th gear redline. Havent found enough space for 5th and 6th yet.
Compared to the normal S I do not feel a difference in power anywhere under 5000 rpm.
Compared to the normal S I do not feel a difference in power anywhere under 5000 rpm.
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From: Indian Land SC
I agree, nothing significant till 5k rpms. But you can notice a slight improvement in normal highway driving at 4k, it picks up just a tad better than "normal".
The stock pulley begins to produce boost at 4k. If you want to see it for yourself, stick a digital voltmeter across the Comptech MAP limiter, from the MAP input (+ meter lead) to the MAP output to the ECM (- meter lead). Anytime there is positive voltage present, manifold pressure is above 1 atm. Negative voltage means the intake manifold is less than 1 atm.
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The stock pulley begins to produce boost at 4k. If you want to see it for yourself, stick a digital voltmeter across the Comptech MAP limiter, from the MAP input (+ meter lead) to the MAP output to the ECM (- meter lead). Anytime there is positive voltage present, manifold pressure is above 1 atm. Negative voltage means the intake manifold is less than 1 atm.
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From: Santa Cruz, CA
Modifry,
If you see a negative voltage in the test you describe then there is something wrong with the ESM.
If the intake manifold pressure is below atmospheric then the MAP sensor will send the ESM a voltage below the cutoff of 2.9V. In this case the output of the ESM should also be the same as the input voltage, below 2.9V. This will produce 0.0V in the test you describe.
If you see a negative voltage in the test you describe then there is something wrong with the ESM.
If the intake manifold pressure is below atmospheric then the MAP sensor will send the ESM a voltage below the cutoff of 2.9V. In this case the output of the ESM should also be the same as the input voltage, below 2.9V. This will produce 0.0V in the test you describe.
