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My boss and I had a disagreement over this a couple weeks ago.

If you have a car with fuel pressure static at, say, 30 psi.

Said car is turbocharged and has a 35 psi wastegate spring.

He says that the injectors would continue to spray fuel but I think that they would be unable to overcome boost pressure and the car would cut out or turn off.

Who is right?
 

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94 dx hatch
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385 Posts
Since the fuel injectors are angled to shoot the fuel in the same direction as the air is moving I would have to say they would continue to spray.

btw if you are running only 30 psi fuel pressure and 35psi of boost, those better be some HUGE injectors lol
 

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91 Civic
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only a 5psi difference it would most just lean pretty bad out in opition and the hundreds of cfms your flowing at 35 pounds of boost will pull fuel out the injector (fuild dymanics). You there are cars that run boost and are carborated aka 0-6 fuel psi.


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1992 Civic Si
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It's not the fuel pressure, it's the pressure DIFFERENCE. Carbs have venturis that create a positive pressure difference to draw fuel out.

A negative pressure difference (-5psi) will not let fuel flow out of the injector.
 

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the artist formerly known as drexelstudent11
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carbs set up for boost have the float bowls referenced to manifold pressure or else the boost pressure blows the fuel right out of the venturi..

go look at a 90's bike with a ram-air setup for a good example of how much vacuum line BS has to be done to make a carb work with positive pressure.

Sentry is right, the fuel would get driven back into the rail... but lets face it, the motor would have melted down before it spooled up high enough to do that.
 
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