Some time ago, there was a discussion and questions asked as to what turbo air injectors are, what do they do and how do they work?
As I have finally managed to get some more information on how air injector’s work, I decided it was worth a post of its own. This may now put to rest some of the previous debate on this thread. They are very tricky to set up and are used on WRC cars and in other high performance motorsports.
So just how do air injectors work and how is the duty cycle calculated? This is a matter of near quantum math’s and would be very difficult to explain in a way that would be understood by the average member of the public - especially me!
Air injectors are used as a control over turbo boost pressure, which is to say if we use a turbo capable of more boost than we want, that extra boost has to be controlled. There are many methods of turbo boost control but air injectors are by far the fastest means of doing so.
Using my engine when it had the T61 Garrett turbo as an example, the turbo is capable of producing a boost pressure of 48 pounds of boost or PSI. With the set up I had, only 32 PSI was required. All boost over this level must not be allowed to enter the engine, as it would be beyond the engines capability. A T61 produces its boost in a very rapid manner and as such a very fast method of control must be used, or excess boost will be produced. If a slower method of boost control is used, as you achieve the desired boost, in this case 32PSI, the boost will go up a few pounds, be controlled and then down a few pounds and be controlled again. This is not desirable as you will have a boost that fluctuates up and down. Air injectors get over this problem due to the fact they operate in milliseconds. (1000 times per second).
However there is a down side and that is if they fail the turbo will continue to produce boost, and in the case of the above engine it will be destroyed very very quickly, (about 35 seconds of full boost). As a result of this risk to the engine a boost cut is employed within the engine control unit which shuts the engine down should an over boost situation occur.
Should the air injector system fail while the vehicle was being driven or tested for that matter the engine control unit WOULD have gone in to shut down mode and no engine RPM over 2500 rpm could have been achieved until such time as the engine control unit was reset.
I hope this helps.
Cheers
Chris
As I have finally managed to get some more information on how air injector’s work, I decided it was worth a post of its own. This may now put to rest some of the previous debate on this thread. They are very tricky to set up and are used on WRC cars and in other high performance motorsports.
So just how do air injectors work and how is the duty cycle calculated? This is a matter of near quantum math’s and would be very difficult to explain in a way that would be understood by the average member of the public - especially me!
Air injectors are used as a control over turbo boost pressure, which is to say if we use a turbo capable of more boost than we want, that extra boost has to be controlled. There are many methods of turbo boost control but air injectors are by far the fastest means of doing so.
Using my engine when it had the T61 Garrett turbo as an example, the turbo is capable of producing a boost pressure of 48 pounds of boost or PSI. With the set up I had, only 32 PSI was required. All boost over this level must not be allowed to enter the engine, as it would be beyond the engines capability. A T61 produces its boost in a very rapid manner and as such a very fast method of control must be used, or excess boost will be produced. If a slower method of boost control is used, as you achieve the desired boost, in this case 32PSI, the boost will go up a few pounds, be controlled and then down a few pounds and be controlled again. This is not desirable as you will have a boost that fluctuates up and down. Air injectors get over this problem due to the fact they operate in milliseconds. (1000 times per second).
However there is a down side and that is if they fail the turbo will continue to produce boost, and in the case of the above engine it will be destroyed very very quickly, (about 35 seconds of full boost). As a result of this risk to the engine a boost cut is employed within the engine control unit which shuts the engine down should an over boost situation occur.
Should the air injector system fail while the vehicle was being driven or tested for that matter the engine control unit WOULD have gone in to shut down mode and no engine RPM over 2500 rpm could have been achieved until such time as the engine control unit was reset.
I hope this helps.
Cheers
Chris