10-15% reduced consumption after "engine split" (physically deactivating 2 of 4 cyl.)

[Frank Lee]

I haven't removed any pistons but I tried disabling 2 and then 1 on my 4 cyl Ford. The triple ran but sounded simply awful.

[JohnAh]

Running a four on three by removing the ignition cable reminds to well of a junkie car... I guess it can´t be any better if the piston is removed too...

Removing TWO cables can give a hint of how the engine will sound after having two pistons removed and there is a big difference if two paralel-going or two "oposing" pistons are disconnected. The engine sounds smoother with two paralel cylinders running but as long as all four pistons are still in place such a test will say nothing about the imbalance when the pistons are removed.

It would be interesting to modify two similar engines and compare them by driving the car. I guess the 360-engine will be easier to drive and produce less vibrations from the power-strokes at low rpm but the 180+520 engine will definitely be more pleasant in total.

[JohnAh]

I guess there are two reasons that an "engine split" will increase fuel efficiency:

Friction losses are reduced when the piston, conrod and valve mechanism is nearly halved. (crankshaft/camshaft bearings are still the same and so is the oil/water pumps) I noticed a huge difference in engine breaking after my "engine split", it almost felt as if I hade put the gears in neutral when I released the throttle.

Even if the reduction in friction losses most likely make a noticabce difference I think more of the improvement comes from the fact that combustion will be more efficient when the cylinder filling/compression is almost doubbled.

An interesting test would be to only disconnect the valves of two cylinders. On a push-rod engine (unlike the Fiat 127 i modified) this may be done very easy by removing the push-rods and/or the adjustment screws for the corresponding rocker arms. The sparkplugs should be left in place with their cables still connected. The cylinder pressure should even out and hopefully there will be no build-up of engine oil above the pistons...
Such a test should show how much of the 10-15% saved fuel is because of the reduced frictions or de improved combustion. This modification would be non destructive and reversible, but also keep the engina balance normal.

The possible problems I see by only disconnecting the valves of two cylinders is what happens to the engine oil on the cylinder walls and how to take care of the rattling cam lifters that may be difficult to remove on some engine designs without ripping appart the entire engine or at least the cylinder head.

[Frank Lee]

That's what I did- pulled the rockers and the injector wires. It wouldn't start on 2 cyls but did on 3.

[rubenova]

Originally Posted by smokey442

I'm currently working on a similar project. Inline 4 cyl gasoline engine. Cylinders 2+3 run in the conventional manner. 1+4 are steam driven using original exhaust valves as steam inlet and original intake as steam exhaust. Traditional radiator is substituted with a heat exchanger that sponges waste heat from engine coolant. Hot water is then pumped into a water jacket that surrounds most of the exhaust system raising it above boiling temperature. The steam engine purist cringe over this but there isn't enough real estate under the hood to accomodate a perpose built steam engine. I did a similar project a few years back using a radial inflow steam turbine mechanically linked to the crank via a cogged belt. 47MPG highway on a 26MPG epa. 150 rear wheel HP vs 118 advertised HP at the crank. Biggest problem was generating quality dry steam to eliminate water slugs that erode turbine blades. Reciprocating steam engines can tolerate some slugs without catastrophic failure. Have to fabricate custom cam core for this to happen but its in the works.

These are some very cool numbers. I'd like to know more on sizing of different exchangers and such of this cogged belt combination. The largest steam turbine I've found was 5 horsepower...and it was just the plans. What did you use? Thanks in advance
rubenova

[MGB=MPG]

an engine that will automatically disable half of its cylinders is the latest thing in big mills.. well maybe not such a new idea ..
look at this 1977 article about the Ford Inline 300CID Dual Displacement engine .. two in one engine .. 6 cyl when required and 3 cyl when on cruise

too bad there was not enough market acceptance in 77 for this to hit mainstream then .. i sure would like that dual displacement on my 91 300CID..

the link will put you on the power curve chart . you will have to scroll up a page or 2 for the whole article

http://books.google.com/books?id=FgE...0curve&f=false

[JohnAh]

Right now I´m thinking about a solution somewhat related to my displacement reduction project. -Instead of the standard solution with a 4-in-line two identical 2-cyl engines on separate gearboxex side by side! This would offcourse be heavier than with a common gearbox and separate cluthces but by having two separate systems I get a unique advantage: reliability! - If one engine or garbox breaks down I can still continue my trip. When extra power is needed both engines will run and also give better traction than with a differential between the wheels. While in eco-mode I can alternate between the two engines to wear them equal or just wear one out before the other.

Two gearboxes for half the load each should be about the same weight as a single transmission minus the weight for the differential. Perhaps more friction losses are added and definitiely more complexity to linkage and engine control. Offset traction while using one engine only may be a obvious problem. There must be an rpm limiter while using both engines in case one tire suddenly lose it´s traction while accelerating.
I don´t think this is a concept for mass production but for a DIY:er it may be interesting. It may also be suitable for "scrapheap challenge enthusiasts" like myself.

Now I just have to check if this crazy concept can fit into an old Saab 96! A unique feature with these cars are their freewheel. The Saab´s longitudinal engine/transaxle placement may be just perfect as long as there is enough room between the wheels. (these cars are quite narrow)

[theycallmeebryan]

Well, the scientist in me got tickled after reading this article.

Yesterday, I disconnected the fuel injector harness and spark plug wires from the 2 center cylinders on my Saturn SL1. It starts, it idles (a little rougher than stock but not bad), it sounds like a wussy version of a v-twin. How does it drive?

After driving it around a parking lot, i didn't think it would have enough power to maintain highway speeds. I was wrong. Besides the fact that it takes about 15-20 seconds to get up to 55mph, it actually holds 55mph on the flats in 5th gear at about 3-5mmHG on the vacuum gauge. Taking hills is quite scary, and i find that i have to downshift way sooner and use much higher rpms to limit the amount of speed lost.

I suspect the A/F ratio is really rich right now, given that air is passing through the center two cylinders without fuel, which is probably causing lean readings from the 02 sensor and dumping tons of fuel into the 2 operating cylinders. I'm sure my MPG is taking a hit overall, but it's fun to experiment!

The car stock with a brand new motor has 100hp and 114ftlb. Right now (182,000miles), the car probably has a 10% hit in performance due to wear. Given the experiences I'm having with this current half engine, and plugging numbers into the Aero+RR calculator on this site, I'd say the torque output is somewhere around 35ftlb or so at the wheels.

So this got me thinking about getting rid of the stock engine and transmission and installing a motorcycle engine that meets those requirements. Some sources say the Saturn Sl1 SOHC engine weighs about 200lbs, and the MP2 transmission is probably about the same. I'm thinking a 800cc +/- in single or v-twin configuration would suffice. I'd also save about 200 lbs.

[JohnAh]

@theycallmeebryan: Nice to see that my crazy project can inspire! I did´t think about the possible problem with clean air being pumped and blended with the exhaust. You are probably right about the sensor reading lean mixture making the injectors dumping a lot more fuel than needed in the remaining two cylinders. Dammit! I was hoping to get a some answer about how much of the fuel savings is comming from the harder work in the remaining cylinders and how much is saved by reduced piston friction.

Is there perhaps an easy way to block the intake manifold or to disengage the valves? Don´t remember if I´ve written this before but I want to try removing all push-rods for two cylinders in my old Saab. Removing the push-rods is easy but the question is what will happen when the valve tappets get lose? Removing them is a LOT more work but perhaps they can be lifted up and locked in place by magnets or a thin strip om metal.
Doing the same trick with an OHC-engine demands most likely a destructive operation.

The test is however very interesting. If fuel consumption can be reduced by 5-10% with all piston still in place there may be a way to modify the engine so it can go from standard mode to "split-mode" while driving.

[theycallmeebryan]

Originally Posted by JohnAh

@theycallmeebryan: Nice to see that my crazy project can inspire! I did´t think about the possible problem with clean air being pumped and blended with the exhaust. You are probably right about the sensor reading lean mixture making the injectors dumping a lot more fuel than needed in the remaining two cylinders. Dammit! I was hoping to get a some answer about how much of the fuel savings is comming from the harder work in the remaining cylinders and how much is saved by reduced piston friction.

Is there perhaps an easy way to block the intake manifold or to disengage the valves? Don´t remember if I´ve written this before but I want to try removing all push-rods for two cylinders in my old Saab. Removing the push-rods is easy but the question is what will happen when the valve tappets get lose? Removing them is a LOT more work but perhaps they can be lifted up and locked in place by magnets or a thin strip om metal.
Doing the same trick with an OHC-engine demands most likely a destructive operation.

The test is however very interesting. If fuel consumption can be reduced by 5-10% with all piston still in place there may be a way to modify the engine so it can go from standard mode to "split-mode" while driving.

If your motor is a pushrod engine, you could remove the pushrods, but your concern about the tappets getting loose is valid. If it's an overhead cam design, you'll have to remove the rocker arms.

Otherwise, i suppose you could remove the intake manifold and cap off the ports to the cylinders you are turning off, using a solid gasket or something.

I suspect that you could achieve a cheap conversion by correcting the A/F ratio and putting the plugs and injectors on a switch.