Turbo Downshift

[Chevy4life1985]

How u guys doing? I was talking to a friend of mine and he said he was told that a turbocharged car could not be downshifted because it would turn the turbine the other way thus breaking it. Is this true? I have no idea on this so i told him i would ask you guys for some help. Any help would be appreciated. Again I have NO idea on this.

[beyondloadedSE]

haha, wow.

No, your turbo will not break. Blow off valves (bypass valves) are included with turbo kits and superchargers for a reason. When the throttle body is closed when letting off the gas during boost or when downshifting without rev matching, that air is diverted either into the downpipe or to the atmosphere to prevent this from happening. I honestly dont know anyone dumb enough to run a hack job turbo or supercharger kit without a BOV or bypass valve. It honestly would have to be a DIY job for somebody not to include one.

[Polygon]

This is one of the dumbest things I've heard someone say about a turbo. There is no way the turbine could reverse direction. If that were possible then the turbo would be the least of your worries.

Tell that person that they don't know shit about turbos and they need to stop giving advice about them. You are perfectly safe to downshift in a turbocharged car.

[Black Lotus]

Originally Posted by Chevy4life1985

How u guys doing?because it would turn the turbine the other way thus breaking it.

About the only way to get a turbo to turn backward in a dynamic situation is to have one hell of a backfire in the intake tract. This would probably damage the compressor also.
Just to clarify, lots of turbo systems were made (factory and otherwise without bypass valves. They are just there for a slight improvement in turbo response, and to protect the compressor from going into surge when you lift off the throttle, which also protects the thrust bearing in the turbo center section. Never heard of anybody routing the bypass gasses into the downpipe. Usually it gets routed back into the intake piping or filter area.

[beyondloadedSE]

Originally Posted by Black Lotus

About the only way to get a turbo to turn backward in a dynamic situation is to have one hell of a backfire in the intake tract. This would probably damage the compressor also.
Just to clarify, lots of turbo systems were made (factory and otherwise without bypass valves. They are just there for a slight improvement in turbo response, and to protect the compressor from going into surge when you lift off the throttle, which also protects the thrust bearing in the turbo center section. Never heard of anybody routing the bypass gasses into the downpipe. Usually it gets routed back into the intake piping or filter area.

sorry, im retarded. For some reason i was thinking wastegate. My wastegate gets routed back into the downpipe. My BOV vents to atmosphere.

[Chevy4life1985]

Yea i thought it was wacky myself. My friends name is Armand. His buddy Dannys (RIP) Father is a mechanic. They told Armand that the reason Danny blew the motor is his Turbocharged Laser was because he was downshifting and it sent the turbo in the opposite direction. Like I said I had no idea if it was possible but it made no sense to me. I guess ILL NEVER take my car to that mechanic LOL.