Hey fellas,

i dont know if you's remember, but back a couple years ago, hemi were making motors that would turn of 2 or 4 cylindars out of the 8.

im guessing that it just cuts the injector out.

this brings me to my question: what would be the consequence of cutting out 2 or 3 of the cylindars on a different car, maybe a magna.

my guess would be that it would do no better on fuel due to the fact the the computer would pick up that the oxygen sensor is reading that there is extra oxygen in the exhaust, and consequently it would just add more fuel into the motor via the remaining injectors.

any thoughts?

its called DOD (displacement on demand) and if you did it would run like a dog

Hey fellas,

i dont know if you's remember, but back a couple years ago, hemi were making motors that would turn of 2 or 4 cylindars out of the 8.

im guessing that it just cuts the injector out.

this brings me to my question: what would be the consequence of cutting out 2 or 3 of the cylindars on a different car, maybe a magna.

my guess would be that it would do no better on fuel due to the fact the the computer would pick up that the oxygen sensor is reading that there is extra oxygen in the exhaust, and consequently it would just add more fuel into the motor via the remaining injectors.

any thoughts?


Not quite. The ECU controls which cylinders fire, and swaps them around to avoid uneven engine heating. Its to save fuel, but without the appropriate ECU magic to go with it, your car will run like a dog. A dead one.

V8s that do this cut back a maximum of 4 cylinders on cruise, but it has to be the right 4 to maintain engine smoothness.

unplug 2 spark leads and find out :)

I wouldnt have a clue how the technology works but I would imagine it could employ a second cam that balances the engine to run on less cylinders, kind of like having a vtec cam

I know it wouldnt run right, and lol at unplugging the spark plug, because it would still use the fuel, lol

http://en.wikipedia.org/wiki/Active_Fuel_Management

This explains a lot.

Feel free to use google any time you have a question. lol

The holden motors actually deactivate the valvetrain from spinning aswell based on oil pressure and a bunch of other factors, so it basically does turn it into a 4cyl.

http://en.wikipedia.org/wiki/Variable_displacement

This too

http://en.wikipedia.org/wiki/Active_Fuel_Management

This explains a lot.

Feel free to use google any time you have a question. lol

not asking how it works anyone can use google. i was wondering what the negative side affects, if any, or possitives, if any, doing this would have on another car.

Honda uses it in their accord V6 but it still only returns 10/100 combined which actually more then other new Aussie sixes. What people don't realize is that its about simple physics car weights X and it requires a certain amount of energy to move it. Even if you turn of 3 cylinders it will still require same amount of energy to move it because the weight of the car is still the same, its just those 3 cylinders will have work harder to do a job that six would normally do (doesn't matter if you a cruising its still the same principle). The worst thing is that the other non working cylinders are still in motion by crank shaft so there is another energy loss. As mentioned above disabling valve train for those cylinders will help but in real life what real benefit is there in terms of fuel saving.

Honda uses it in their accord V6 but it still only returns 10/100 combined which actually more then other new Aussie sixes. What people don't realize is that its about simple physics car weights X and it requires a certain amount of energy to move it. Even if you turn of 3 cylinders it will still require same amount of energy to move it because the weight of the car is still the same, its just those 3 cylinders will have work harder to do a job that six would normally do (doesn't matter if you a cruising its still the same principle). The worst thing is that the other non working cylinders are still in motion by crank shaft so there is another energy loss. As mentioned above disabling valve train for those cylinders will help but in real life what real benefit is there in terms of fuel saving.

next to none, while the idea is there, it doesnt work very well, if you want good fueleconomy, buy a pushbike or moped

it works well for the chrysler 300C 11.8l / 100ks for a 5.6l hemi V8!

Holden also have good fuel saving on the V8 range with AFM

Yea holden claims up 1 litre/100 savings obviously thats not bad but dont forget its a 6.0 V8. In reality if we are talking about smaller engine lets say 3.5 V6 there would be hardly any diffrenence.

the other part of me say's, if your driving a 6L V8 pushrod, Why are you concerned about saving fuel?

;1320344']the other part of me say's, if your driving a 6L V8 pushrod, Why are you concerned about saving fuel?

I just think "What horrible eco for a V4 3L" :P

The physics of it says 80% of the energy in petrol goes out the exhaust pipe or into the cooling system. Someone was experimenting with an engine with ceramic parts in it. If you could allow the engine to run at really high temperatures, you don't need a cooling system and if you scavenge the energy in the hot exhaust with turbochargers, you could in theory end up with a very efficient engine. Haven't heard about it lately, and I can see problems - like how do you lubricate super hot moving parts?

Would Teflon had the right qualities to lubricate? Similar to say how they use a Teflon film on frying pans and the such?

Get chuck norris to spit on them. Will lubricate for the next 10000 years