Cylinder Deactivation?
 

I'm trying to think of a reason that would prevent me from setting up my own cylinder deactivation mode with a switch.

To me it seems that all you would need to do would be to setup a switch that would cut spark at the spark plug wires and cut the electricity to the fuel injectors. You'd have to think about which cylinders to cut to keep the engine balanced but that would be easy.

Am I missing something here? The only problem that I could see with this is that it might trip the 02 sensor out, half of the cylinders would be pumping atmosphere out the exhaust. But that's the only problem I could see with this. It wouldn't trip the knock sensors out... Am I crazy?

Yeah, I don't think you'll notice the difference between 8mpg and 6mpg that much :huh:

I get 20+ on the highway wise guy.

And I'm talking about the Neon. Wouldn't work with the Vette, the carb dumps fuel at the top of the manifold, so there is no way to regulate it between cylinders. But the Neon injects the fuel into the manifold right above the cylinder.

Now that I think about it, there might not even be a need to cut spark. If there is little to no fuel in the chamber it wouldn't matter... I think? Might be as simple as hooking up two of the fuel injectors to a switch.

Let me get this straight, you want to cut your 4 cylinder down to a 2 cylinder? What the hell is wrong with you? Just go buy a Vespa or a Segway if you care so much about gas mileage :nutkick:

P.S. I strongly endorse your project, PLEASE, PLEASE take pictures - I can't wait to see the results.

Yesss. It doesn't take 150 hp to keep my lil 2500 pounder at a constant speed on the highway.

Take pics of what? Splicing a wire? I'm really not even sure that this would work, but someone's done it before.

You aren't making anywhere near 150 BHP at a constant speed on the freeway, unless it's at peak HP somewhere in the vicinity of Red Line. Try more like 40 (or less). Reduce by two cylinders and you'll be making well less than half of that, probably not enough to maintain freeway speed. Remember, your remaining two cylinders (4 stroke cycle) not only have to do enough work over time (power) to maintain a constant speed against drag, etc., but have to compress the two deactivated cylinders and spin the whole rotating assembly. My guess is that if it worked at all, you'd be finding yourself at higher revs to make similar power and not save any fuel, while increasing wear on the engine. This is my hypothesis. Please test and report. :)

The engine spins at 4K rpm at 80mph, the speed at which I typically cruise on the freeway. You really think my engine is only making 40hp at 4K rpm?

The best thing to do would be to get a custom 5th gear made to put me around 2500rpm at 80mph. But that would be a PITA and I'm not even sure how I'd go about it.

But the reason I posted this thread, I was looking for flaws in the actual mechanics of my plan. Would this work? Am I missing something? Would it in fact trip the 02 sensor out? What do you guys think?

The computer would absolutely lose its mind. It would be registering insufficient fuel flow, failing injectors, a massively lean condition, as well as an ignition fault. If youre lucky, youd end up with a check engine light. If unlucky, "limp" mode and horrible mileage. Also, your 02s measure lean, and the computer will add fuel...meaning your remaining 2 cylinders would run really rich, besides that, youd have to alternate cylinders, as without fuel going into the remaining two cylinders i think youd find theyd get REALLY hot REALLY fast, fuel really being the only thing that cools them. You may lose valve seats or scuff cylinders. Intriguing idea though, itd be neat to see if it could be made to work.

Failing injectors is something that did slip my mind, can't think of a way to get by that. And I figured I could fix the 'massively lean condition' or O2 sensor problem with a resistor. But I guess it's not happening now.

Out of curiosity though, about the fuel keeping the piston cool, I wouldn't think that it would be a problem. Without the combustion happening I would think that the oil and coolant would be enough to keep the piston cool, wouldn't you? I mean, it seems to work for Dodge.