Active Fuel Management
09-25-2012, 10:18 PM
#1
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Active Fuel Management So I think we all know about Active Fuel Management. Incase you dont it allows a V6 or V8 engine to "turn off" half of the cylinders under light-load conditions to improve fuel economy. Estimated performance on EPA tests show a 5.5%-7.5% improvement in fuel economy. Was wondering since GM's current Active Fuel Management technology uses a solenoid to deactivate the lifters on selected cylinders of a pushrod V-layout engine & LS Lifters are interchangeable with all small blocks. Could this same technology be used on LT1/4's and Gen 1 SBC?
09-25-2012, 10:36 PM
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After some quick research it looks like you were on wiki looking for this information. What I learned after reading past the first paragraph was this...
There are apparently two different generations of this "AFM" (which was only called that after 2004). While it does not go in to very great detail as to how the 1st generation works this is what I read about the second gen of fuel management.
"In 2004, the electronics side was improved greatly with the introductions of Electronic Throttle Control, electronically controlled transmissions, and transient engine and transmission controls. In addition, computing power was vastly increased. A solenoid control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylinders [1]. Unlike the first generation system, only half of the cylinders can be deactivated. It is notable that the second generation system uses engine oil to hydraulically modulate engine valve function. As a result, the system is dependent upon the quality of the oil in the engine. As anti-foaming agents in engine oil are depleted, air may become entrained or dissolve in the oil, delaying the timing of hydraulic control signals. Similarly engine oil viscosity and cleanliness is a factor. Use of the incorrect oil type, i.e. SAE 20W40 instead of SAE 20W50, or the failure to change engine oil at factory recommended intervals can also significantly impair system performance"
So no, there is no easy or cheap way to do this conversion.. If at all.
There are apparently two different generations of this "AFM" (which was only called that after 2004). While it does not go in to very great detail as to how the 1st generation works this is what I read about the second gen of fuel management.
"In 2004, the electronics side was improved greatly with the introductions of Electronic Throttle Control, electronically controlled transmissions, and transient engine and transmission controls. In addition, computing power was vastly increased. A solenoid control valve assembly integrated into the engine valley cover contains solenoid valves that provide a pressurized oil signal to specially designed hydraulic roller lifters provided by Eaton Corp. and Delphi. These lifters disable and re-enable exhaust and intake valve operation to deactivate and reactivate engine cylinders [1]. Unlike the first generation system, only half of the cylinders can be deactivated. It is notable that the second generation system uses engine oil to hydraulically modulate engine valve function. As a result, the system is dependent upon the quality of the oil in the engine. As anti-foaming agents in engine oil are depleted, air may become entrained or dissolve in the oil, delaying the timing of hydraulic control signals. Similarly engine oil viscosity and cleanliness is a factor. Use of the incorrect oil type, i.e. SAE 20W40 instead of SAE 20W50, or the failure to change engine oil at factory recommended intervals can also significantly impair system performance"
So no, there is no easy or cheap way to do this conversion.. If at all.
'd like this in a LONG time!
09-26-2012, 06:47 AM
#4
If you could do it, which you pretty much can't, it would cost FAR more than what you would save.
Then there is the the fact that pretty much everyone I have talked to with an AFM vehicle HATES the AFM. One friend with an Avalanche says his newer one with the AFM actually gets WORSE mileage. The EPA test procedures are badly flawed which is why you get numerically low gearing that lugs engine and hurts mileage in real life.
Now if you wanted to actually try and save a buck you could work on a lean cruise program. The 14.7:1 AFR the pcm commands at cruise is best for PPM emissions that is NOT to say it is best for economy. Making that work out is just a matter of a lot of time put into tuning. I have heard some reports that if you can use a hex editor lean cruise is buried in the 94-95 pcm programming. You can play with decel fuel cutoff and such too.
Work with what you have rather than trying to reinvent the wheel.
Then there is the the fact that pretty much everyone I have talked to with an AFM vehicle HATES the AFM. One friend with an Avalanche says his newer one with the AFM actually gets WORSE mileage. The EPA test procedures are badly flawed which is why you get numerically low gearing that lugs engine and hurts mileage in real life.
Now if you wanted to actually try and save a buck you could work on a lean cruise program. The 14.7:1 AFR the pcm commands at cruise is best for PPM emissions that is NOT to say it is best for economy. Making that work out is just a matter of a lot of time put into tuning. I have heard some reports that if you can use a hex editor lean cruise is buried in the 94-95 pcm programming. You can play with decel fuel cutoff and such too.
Work with what you have rather than trying to reinvent the wheel.
09-26-2012, 10:44 AM
#5
If you could do it, which you pretty much can't, it would cost FAR more than what you would save.
Then there is the the fact that pretty much everyone I have talked to with an AFM vehicle HATES the AFM. One friend with an Avalanche says his newer one with the AFM actually gets WORSE mileage. The EPA test procedures are badly flawed which is why you get numerically low gearing that lugs engine and hurts mileage in real life.
Now if you wanted to actually try and save a buck you could work on a lean cruise program. The 14.7:1 AFR the pcm commands at cruise is best for PPM emissions that is NOT to say it is best for economy. Making that work out is just a matter of a lot of time put into tuning. I have heard some reports that if you can use a hex editor lean cruise is buried in the 94-95 pcm programming. You can play with decel fuel cutoff and such too.
Work with what you have rather than trying to reinvent the wheel.
Then there is the the fact that pretty much everyone I have talked to with an AFM vehicle HATES the AFM. One friend with an Avalanche says his newer one with the AFM actually gets WORSE mileage. The EPA test procedures are badly flawed which is why you get numerically low gearing that lugs engine and hurts mileage in real life.
Now if you wanted to actually try and save a buck you could work on a lean cruise program. The 14.7:1 AFR the pcm commands at cruise is best for PPM emissions that is NOT to say it is best for economy. Making that work out is just a matter of a lot of time put into tuning. I have heard some reports that if you can use a hex editor lean cruise is buried in the 94-95 pcm programming. You can play with decel fuel cutoff and such too.
Work with what you have rather than trying to reinvent the wheel.
Yes, he can't retrofit it into an LT1, we can all agree on that.
09-26-2012, 02:37 PM
#6
TECH Apprentice
I would think that the only "affordable" way to get AFM in an F-body would be to do a complete engine swap to an engine with AFM and then try to get all the programming to work happily (if even possible)... Still probably not worth the mileage gain either way...
09-26-2012, 04:22 PM
#7
Correct on the swap, you'd have to swap the motor, pcm and everything. I bet it would get insane mileage being in a light f-bod though. It would be able to stay in v-4 mode much longer than in a heavy truck. 20-25 in town and 35 on the thruway would be attainable.
