Engine/Transmission (1998.5 - 2002) Turbo Question

[Silver_Ram]

I work with a guy (he's one of those street racer wannabe's) that asked me a question about the Cummins Diesel & I don't know the answer.



You mash the go pedal & build up 20lbs of boost or more, then you let off the pedal. What happens to the built up pressure?



Thanks,



Troy

 

[JGK]

Often, you hear the air charge flow back through the compressor side, which tries to spin the turbo backwards. The sound you hear is a woof-woof-woof. That's the dreaded "barking" of the turbo. It can break them.



Other times it will just be consumed by the engine and you won't hear or feel anything unusual. Just depends on the turbo, boost pressure, etc. When you back off the throttle, you're not closing down access of the air to the cylinders like in a gasser, just the flow of fuel. So the charge still gets passed through the engine.



-Jay

 

[Tcolesanti]

Like JGK said, you let off the go pedal the fuel stops, well, fuel spins the turbo, when the fuel stops the turbo slows, still consuming the last bit of air but without any fuel, indicated by the pyrometer dropping like a rock