Finding blow off valve pressure
03-14-2007, 10:07 PM
#1
0.5 BAR
Thread Starter
Join Date: Mar 2006
Posts: 56
Finding blow off valve pressure
Ive read and read about turbo theory and compressor maps. On top of this im about 2.5 years into a 4 year mechanical engineering degree, and I still cannot figure one thing out.
Boost pressure is always measured at the waste gate, so off the exhaust gas. But how do you know the pressur of the intake air in the charge piping going into the motor. Sure this can be read by the map sensor, but id imagine youd want to know how much pressure your going to be building before you get there.
You could calculate the intake pressure from the pressure ratio accross the compressor * atmospheric pressure, but how does the pressure ratio vary with boost pressure?
im lost...
Boost pressure is always measured at the waste gate, so off the exhaust gas. But how do you know the pressur of the intake air in the charge piping going into the motor. Sure this can be read by the map sensor, but id imagine youd want to know how much pressure your going to be building before you get there.
You could calculate the intake pressure from the pressure ratio accross the compressor * atmospheric pressure, but how does the pressure ratio vary with boost pressure?
im lost...
03-14-2007, 11:49 PM
#2
0.0 BAR
Join Date: Apr 2006
Posts: 0
Re: Finding blow off valve pressure
ive thought about this before.
like external wg's. your o2 sensor isnt reading all of the exhaust gasses. sure, it should be the same, but you know, its the logic behind it
and, you're dumb.
boost pressure is measured via intake side, but regulated exhaust side
like external wg's. your o2 sensor isnt reading all of the exhaust gasses. sure, it should be the same, but you know, its the logic behind it
and, you're dumb.
boost pressure is measured via intake side, but regulated exhaust side
03-15-2007, 12:01 AM
#4
3.0 BAR
Join Date: Feb 2006
Posts: 3,906
Re: Finding blow off valve pressure
Originally Posted by kamilk69
---- whats with all the math lately,
its simple, boost + enigne = massive burnouts
its simple, boost + enigne = massive burnouts
if you are not moving in your honda and you do a burnout and only one wheel spins your speedo will read say 140km/h.
how fast is that tire spinning?
03-15-2007, 12:29 AM
#5
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Join Date: Apr 2006
Posts: 0
Re: Finding blow off valve pressure
Originally Posted by Zeniceguycrx
for the math guy...
if you are not moving in your honda and you do a burnout and only one wheel spins your speedo will read say 140km/h.
how fast is that tire spinning?
if you are not moving in your honda and you do a burnout and only one wheel spins your speedo will read say 140km/h.
how fast is that tire spinning?
03-15-2007, 09:25 AM
#6
0.5 BAR
Thread Starter
Join Date: Mar 2006
Posts: 56
Re: Finding blow off valve pressure
Originally Posted by c0mpl3x
ive thought about this before.
like external wg's. your o2 sensor isnt reading all of the exhaust gasses. sure, it should be the same, but you know, its the logic behind it
and, you're dumb.
boost pressure is measured via intake side, but regulated exhaust side
like external wg's. your o2 sensor isnt reading all of the exhaust gasses. sure, it should be the same, but you know, its the logic behind it
and, you're dumb.
boost pressure is measured via intake side, but regulated exhaust side
Exhaust pressure of say 10psi, makes for an intake manifold pressure of how much?
03-15-2007, 12:08 PM
#8
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Join Date: Dec 2004
Posts: 1,976
Re: Finding blow off valve pressure
Originally Posted by juce
Boost pressure is always measured at the waste gate, so off the exhaust gas.
Originally Posted by juce
Exhaust pressure of say 10psi, makes for an intake manifold pressure of how much?
03-15-2007, 12:42 PM
#9
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Join Date: May 2006
Posts: 1,967
Re: Finding blow off valve pressure
Originally Posted by c0mpl3x
boost pressure is measured via intake side, but regulated exhaust side
The blowoff valve will only go off when the intake manifold pressure drops (vacuum), and the throttle plate closes infront of your boost pressure. That is why a vacuum line goes to the BOV, it opens in vacuum when the boost in the charge pipe pushes it open.
Help any?
