I have a question about my SC
Thread Starter
Registered User
Joined: Jan 2002
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From: Aschaffenburg, Germany
I have a question about my SC
Hi,
i have lately installed comptech supercharger + aftercooler. Also i have a DEFI-Boost Gauge.
Unfortunatly i cannot testdrive my car till 1st March, because of my seasonal license plate (Germany).
I wanted to check the Boost. So far i let the oil warm up. After that i reved in neutral to 9K.
But the boost gauge shows me only 0.1 kpa. If i play now with the gas pedal i can get it up to 0.45 kpa.
I am not so experienced with FI cars, so is this normal? Does i have to drive my car to get the correct boost numbers on the Boost-Gauge?
Thanks in forward for all your help
i have lately installed comptech supercharger + aftercooler. Also i have a DEFI-Boost Gauge.
Unfortunatly i cannot testdrive my car till 1st March, because of my seasonal license plate (Germany).
I wanted to check the Boost. So far i let the oil warm up. After that i reved in neutral to 9K.
But the boost gauge shows me only 0.1 kpa. If i play now with the gas pedal i can get it up to 0.45 kpa.
I am not so experienced with FI cars, so is this normal? Does i have to drive my car to get the correct boost numbers on the Boost-Gauge?
Thanks in forward for all your help
Former Moderator
Joined: Sep 2002
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From: Mother F'in TN
On a Vortech equipped car, you will see 20in hg. of vacuum at idle. The Vacuum will drop to 0in hg as the throttle opens, and load increases. Boost starts to come into play around 4000 rpm, and builds to peak at redline. The comptech #'s should be roughly the same.
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From: Sydney
When you rev the car in neutral you only use partial throttle and it will go to redline as there is little to no load on the engine. So the vacuum in the intake manifold keeps the bypass open and you don't see boost.
You can only safely go whole open throttle when you have load. When you are driving you go WOT and there is no restriction between the blower and the intake so the pressure builds and the bypass stays closed.
If you have the Defi HUD Boost gauge you would see 0.38kg/cm2 at 9000 rpm WOT. That equates to about 5.4psi. Actually you'll see a little less as the air will be cooler and denser with the AC.
You can only safely go whole open throttle when you have load. When you are driving you go WOT and there is no restriction between the blower and the intake so the pressure builds and the bypass stays closed.
If you have the Defi HUD Boost gauge you would see 0.38kg/cm2 at 9000 rpm WOT. That equates to about 5.4psi. Actually you'll see a little less as the air will be cooler and denser with the AC.
Joined: Jan 2003
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From: MIAMI
Originally posted by AusS2000
When you rev the car in neutral you only use partial throttle and it will go to redline as there is little to no load on the engine. So the vacuum in the intake manifold keeps the bypass open and you don't see boost.
You can only safely go whole open throttle when you have load. When you are driving you go WOT and there is no restriction between the blower and the intake so the pressure builds and the bypass stays closed.
If you have the Defi HUD Boost gauge you would see 0.38kg/cm2 at 9000 rpm WOT. That equates to about 5.4psi. Actually you'll see a little less as the air will be cooler and denser with the AC.
When you rev the car in neutral you only use partial throttle and it will go to redline as there is little to no load on the engine. So the vacuum in the intake manifold keeps the bypass open and you don't see boost.
You can only safely go whole open throttle when you have load. When you are driving you go WOT and there is no restriction between the blower and the intake so the pressure builds and the bypass stays closed.
If you have the Defi HUD Boost gauge you would see 0.38kg/cm2 at 9000 rpm WOT. That equates to about 5.4psi. Actually you'll see a little less as the air will be cooler and denser with the AC.
Wayne.
Maybe with the aftercooler you can get the same psi o higher since the air is more denser is easyier to the turbine to spool, if the air is very fine is harder to spool into the intake.
-Juan
BTW thanks for the map
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Joined: Oct 2000
Posts: 30,809
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From: Sydney
At the SC the air is ambient temp. it is then accelerated and compressed and hence heats up. It' not unitl it hits the AC that it is cooled.
So basically the air going through the throttle body is exactly the same amount of air (not allowing for restriction), only cooler, less dense, and lower pressure.
One problem you could have is that the fuel pressure is proportionate to the air pressure (due to the FPR) and makes no adjustment for its temperature or density. I would imagine that if you just add an AC to your Comptech setup you would be running slightly leaner. Not sure if it is relevant or not though. I'll tell you when I get my AC.
So basically the air going through the throttle body is exactly the same amount of air (not allowing for restriction), only cooler, less dense, and lower pressure.
One problem you could have is that the fuel pressure is proportionate to the air pressure (due to the FPR) and makes no adjustment for its temperature or density. I would imagine that if you just add an AC to your Comptech setup you would be running slightly leaner. Not sure if it is relevant or not though. I'll tell you when I get my AC.
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From: MIAMI
Originally posted by AusS2000
At the SC the air is ambient temp. it is then accelerated and compressed and hence heats up. It' not unitl it hits the AC that it is cooled.
So basically the air going through the throttle body is exactly the same amount of air (not allowing for restriction), only cooler, less dense, and lower pressure.
One problem you could have is that the fuel pressure is proportionate to the air pressure (due to the FPR) and makes no adjustment for its temperature or density. I would imagine that if you just add an AC to your Comptech setup you would be running slightly leaner. Not sure if it is relevant or not though. I'll tell you when I get my AC.
At the SC the air is ambient temp. it is then accelerated and compressed and hence heats up. It' not unitl it hits the AC that it is cooled.
So basically the air going through the throttle body is exactly the same amount of air (not allowing for restriction), only cooler, less dense, and lower pressure.
One problem you could have is that the fuel pressure is proportionate to the air pressure (due to the FPR) and makes no adjustment for its temperature or density. I would imagine that if you just add an AC to your Comptech setup you would be running slightly leaner. Not sure if it is relevant or not though. I'll tell you when I get my AC.
I will get my wideband today I will tell you if my set up is lean or not ( A/F must be 12-13 to be ok right?)
Joined: Jan 2003
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From: MIAMI