Creating a Switch to Shut Off Cylinders on the Fly

[GasSavers_bense]

well here's the deal. you have 4 pistons (obviously) and so two of them go down, two of them come up. however it is the middle pistons that go down and the outer pistons that come up. by doing this, the motor is balanced at all times. the combustion is being put on the middle two pistons pushing them away from the head to the bottom (BDC bottom dead center) and pushing the outer two pistons to the head to the top of the combustion chamber (TDC top dead center)

if you were to disable any of the pistons, you would want to disable one of the inner two pistons and one of the outer pistons. pistons are numbered 1,2,3,4 you could either disable pistons 1 and 3 and have pistons 2 and 4 firing. Or have pistons 4 and 2 disabled and have pistons 1 and 3 firing.

now, i am not sure, however, my hypothesis is this. even if you were going to get those pistons disabled while cruising. you would have to push harder on the gas and make these two pistons work harder than they normally would.

as far as disabling a injector. the spark plug would be doing the same thing as strikign the flint on a lighter without pushing the button that releases the butane. It would spark, and that's it.

i am not necesarily sure if running on two cylinders would be advantageous or not. it makes me wonder though.

[Matt Timion]

Originally Posted by bense

now, i am not sure, however, my hypothesis is this. even if you were going to get those pistons disabled while cruising. you would have to push harder on the gas and make these two pistons work harder than they normally would.

i am not necesarily sure if running on two cylinders would be advantageous or not. it makes me wonder though.

I was thinking the same thing actually. Wouldn't RPM go up at this point? Wouldn't the ECU detect a very lean mixture coming out of the exhaust and start running the two remaining injectors REALLY rich? Wouldn't this lead to wasted fuel?

[SVOboy]

Might as well post up this, but I recently learned this is impossible on dpfi engines because it is usually running on only one injector and then the second injector kicks in under heavy load. So I'd end up killing the only injector.

[Matt Timion]

Originally Posted by SVOboy

Might as well post up this, but I recently learned this is impossible on dpfi engines because it is usually running on only one injector and then the second injector kicks in under heavy load. So I'd end up killing the only injector.

How odd. I guess this is the reason why people call DPFI a "glorified carb."

That's all it really is... just a glorified carb with fuel injectors.

MPFI seems to be the way to go.

[kickflipjr]

I would be able to do this on my car fairly easily. But it seems like it would be bad on the engine. With 2 cyl getting no fuel, wouldn't it put wear on the cylanders not getting any fuel.

[SVOboy]

It should only put as much wear on them as they would get normally, mehbe less because things are blowing up in there.

[b1gmoose]

Do you disable the spark plugs as well? Wouldn't a sparkplug not burning any fuel on the compression stroke burn a hole in the top of the cylinder after say 10K miles or so? Any ideas?

~ryan

[Matt Timion]

Originally Posted by b1gmoose

Do you disable the spark plugs as well? Wouldn't a sparkplug not burning any fuel on the compression stroke burn a hole in the top of the cylinder after say 10K miles or so? Any ideas?

~ryan

I'm not sure how a spark without fuel would be more damaging than a spark WITH fuel. It seems to me that the violent explosion would be more damaging than a tiny little spark.

[SVOboy]

Originally Posted by Matt Timion

I'm not sure how a spark without fuel would be more damaging than a spark WITH fuel. It seems to me that the violent explosion would be more damaging than a tiny little spark.

I agree, though it's easy enough just to hook the switch up along the spark plug wires if you so wish.

[Matt Timion]

Originally Posted by SVOboy

I agree, though it's easy enough just to hook the switch up along the spark plug wires if you so wish.

Agreed. It would be best to do the switch to turn off both the injectors and the spark plugs. This would also increase the life of your plugs.