Displacement on Demand...make your own?

[Jamescase10]

If I unplugged 2 sparkplug wires and there fuel injectors, would I ruin the engine? Would I save gas? would it matter if there valves are opening and closing even though theres no spark and no fuel? Would it be just like the dod system, except the valves are still workin? would it ruin the piston rings like my dad thinks because gas is a upper cyl lube? ( according to him) ??????????????

[nikita7]

IMO you will kill the engine. As far as I understand it, its like having a misfire in 2/4 of your cylinders. Your engine is not designed to work like DoD engines. DoD engine is controlled by computer that switches off half of the cylinders automatically. If I do not sound to clear about DoD concept, I am sorry I never had a chance to read about how it works. But as it is DO NOT try to make your own DoD.

[beef_bourito]

what kind of engine is it?

if it's a V engine try to have the cylenders firing on opposite sides, this will keep the engine a little more balanced.

but you'd also want to have the exhaust valve open all the time because if not you're going to be compressing the air you sucked in and it's going to hurt performance and gas mileage.

i wouldn't suggest doing this because you're probably not going to see much of an improvement over current mileage. the people who design it for the car test and improve the system so many times before it hits the market, you have no chance to do anything close to the job they do. if you try to do it though tell us how it works for you.

[C2Z06]

That will give you two cyclander of dead wait and extra load on the other two cylanders. It might not help. The extra mass not working would probably fuel economy. It's one reason why it's easier for OHC motors to get better mileage than OHV...less mass to move that's not working for you at a given time.

[GreyGoose006]

in a true DOD engine the valves of the cylinders are shut when the cylinders are not in use. this minimizes losses in power due to friction and the pumping of the cylinders.

DONT DO IT... you will kill the engine, and your gas mileage

[Ian Szgatti]

i hate to resurect such an old thread... ok, i dont, but regardless.. all the extra o2 in the exhaust stream would cause you to run sickeningly rich, foul up your operating plugs, likely causing misfires, deposits, preignition, catalyst failure, detonation. The difference in tempretures over the head would probablly lead to some kind of funky warpage.. leading to stress cracks, leaks, you know... besides that, at least your tires wouldnt fall off. Sorry, this topic made me chuckle.

[GreyGoose006]

not to mention the fact that the gas running down the cylinder walls would disolve the oil and de-lube the cylinder causing lots of extra wear and heat.

in a true DOD engine, the injectors shut off on one half of the Vee, and the intake and exhaust valves lock shut. wait, i already said that.
still not a good idea.

oh, and yeah, old thread, i know.

[Ian Szgatti]

Originally Posted by GreyGoose006

not to mention the fact that the gas running down the cylinder walls would disolve the oil and de-lube the cylinder causing lots of extra wear and heat.

sweet... this is starting to sound like a nice set up...

[GreyGoose006]

yeah, a dead engine really rurns me on too.

[2.2 Straight six]

Originally Posted by GreyGoose006

not to mention the fact that the gas running down the cylinder walls would disolve the oil and de-lube the cylinder causing lots of extra wear and heat.

he said he's disconnect the fuel injector cable. so they wouldn't be active. no fuel in the cylinder, no cylinder washing.

[GreyGoose006]

ok, so i missed that part...
ummm. yeah.

[SaabJohan]

Originally Posted by Jamescase10

If I unplugged 2 sparkplug wires and there fuel injectors, would I ruin the engine? Would I save gas? would it matter if there valves are opening and closing even though theres no spark and no fuel? Would it be just like the dod system, except the valves are still workin? would it ruin the piston rings like my dad thinks because gas is a upper cyl lube? ( according to him) ??????????????

You need to unplug the fuel injectors and the lambda sensor.

Fuel doesn't lubricate the cylinders so no danger there.

The danger is that you get excessive afterburning in the exhaust manifold when the engine is running rich. If your car has a catalytic converter you can say bye bye to it.

Perhaps you can save some fuel, but since you can't control the valves I doubt it.

[GreyGoose006]

ok, you must not have read the previous posts.
we know that gas dosent lube the cylinder walls.
gas de-lubes cylinder walls.
however, since the injectors for those cylinders would be unplugged there is no problem there.

the problem comes when you have the cylinders moving up and down doing absolutely no work, and creating drag by rubbing on the cylinder walls.

in a true DOD engine, when it is running on fewer cylinders, the valves shut as soon as the power stroke is over and the engine reached BDC. this prevents losses due to compressing then releasing the air in the cylinders. if the valves remain open you have to draw air in, compress it, decompress it, recompress it, release it, and draw more air in. if the valves stay shut, then it is doing 0 total work.

IMO, the gas mileage would plummit if the engine were not set up from the factory for DOD. also, without some serious electronics, there would be no on demand, just less displacement.


this is the second time this thread has been brought back from the dead...

[SaabJohan]

Originally Posted by GreyGoose006

ok, you must not have read the previous posts.
we know that gas dosent lube the cylinder walls.
gas de-lubes cylinder walls.
however, since the injectors for those cylinders would be unplugged there is no problem there.

the problem comes when you have the cylinders moving up and down doing absolutely no work, and creating drag by rubbing on the cylinder walls.

in a true DOD engine, when it is running on fewer cylinders, the valves shut as soon as the power stroke is over and the engine reached BDC. this prevents losses due to compressing then releasing the air in the cylinders. if the valves remain open you have to draw air in, compress it, decompress it, recompress it, release it, and draw more air in. if the valves stay shut, then it is doing 0 total work.

IMO, the gas mileage would plummit if the engine were not set up from the factory for DOD. also, without some serious electronics, there would be no on demand, just less displacement.


this is the second time this thread has been brought back from the dead...

An engine doesn't release compressed air, it compress, exapand and then release the air. It would still be pumping losses though. But the pumping losses in the running cylinders would be smaller than ordinary.

[Ian Szgatti]

Originally Posted by GreyGoose006

if the valves stay shut, then it is doing 0 total work.

If the valves saty shut, the strokes create vaccume, which could potentially suck oil into the cylinder as well as create a resistence for the other cylinders to overcome. On the other hand, the vaccume might aid in the upstroke of that piston.
I'm not sure... to even talk about this makes us the craziest, most bored people in the whole of automotive forums... and Jamescase 10 is the headmaster...
Oh what great leader do we speak of next? Peanut butter as an oil additive? Wood spoked wheels as a method of weight reduction? Driving only downhill to save gas?