• If you log in, the ads disappear in the forum and gallery. If you need help logging in or getting registered, send request to: webmaster@southernairboat.com

Lycoming Running without spark plugs

Short round

Well-known member
Smarter Plugs

The spark plug is an intrinsic part of the gasoline internal combustion engine. It has been around in its various iterations ever since the early gasoline engineers figured out that gasoline would not combust on its own and that they needed a spark timed to go off when the piston is at the correct position. The modern spark plug is a superbly evolved piece of hardware that can fire a mixture 5000 times a minute and go without any adjustments for a hundred thousand miles.

Mark Cherry wants to make it obsolete. Cherry runs a company called Automotive Resources in Idaho and has invented a spark plug replacement that he calls the 'smart plug.' The smart plug is intended as a bolt-on replacement for the spark plug and is designed to do things that the spark plug can never do. The smart plug is a self-contained catalytic ignition unit that can be retrofitted to just about any engine and burn a number of fuels.

The smart plug takes the catalytic process out of the tail pipe and into the engine. It is a lot like a model aircraft glow plug, which Cherry says was the original inspiration. It has a prechamber with a catalytic heating element. Screwed into the spark plug hole, the smart plug has a cylindrical chamber with a catalytic rod in the middle. The tip heats up and ignites the small fraction of the air/ fuel mixture that is in the cylindrical chamber. The mixture then explodes out of the smart plug and ignites the rest of the combustion chamber gas. The flames enable a far more complete combustion than is possible with a conventional spark plug.

One of the major advantages of using the smart plug is that it can eliminate the rest of the conventional ignition circuit. It does not require distributors, coils, or points. Eliminating these items cuts out the radio frequency interference that a normal system throws out. In aircraft usage, this capability alone would be a significant advantage. Initial start up requires about 6 W of electric current for the heating element to come up to operating temperature. But after the initial warm up, the smart plug is self-contained, requiring no electricity to continue functioning. The heat of the combustion stays in the smart plug and enables it to combust additional combustion cycles continuously.

The smart plug enables combustion of a variety of fuels including a mixture of ethanol and water. Water-based fuels are a spark plug's nightmare, but the smart plug has no problems with combusting a water-rich mixture. In the future, as we shift to renewable fuels, this might be a significant enabler. The smart plug also enables combustion of fuels, such as diesel and kerosene, in low-compression gasoline engines. The smart plug can also be retrofitted to existing diesel engines by replacing the injectors with smart plugs and using conventional gasoline injection hardware.

Smart plugs have been tested out on a reconditioned Lycoming O-200 engine with the aircraft taking off, flying, and landing entirely without spark plugs. It has also been tested on a variety of engines including various two strokes, four strokes, and rotaries using a number of fuels. The only constraint is that leaded gas contaminates the platinum catalyst in the smart plug (as it does for platinum in catalytic converters), leading to deteriorated performance as the contamination increases.

Mark Cherry and his team in Sandpoint, Idaho, are currently pursuing military applications where the multifuel capabilities provide relief to fuel supply logistics issues. With the entire military standardizing on diesel fuel, this technology enables the military to also run its gasoline generators on diesel fuel.


Mark Cherry

Automotive Resources Inc., Idaho.

Phone: 208-265-2723

E-mail: markc@smartplugs.com

URL: http://www.smartplugs.com

To comment on this article, write to us at tiresearch@frost.com

To find out more about Technical Insights and our Alerts, subscriptions and research services, access http://ti.frost.com

I love it when people think outside the box. This will be fun to follow.

First thought is, how do you adjust spark timing ?
This could be big.

Second question is how do you deal with vales that need the lead in older Lycoming engines?

Seems that a diesel engine, or should I say a gasoline engine
running on diesel would still need a high pressure injection
system to atomize the fuel. and that timing must be interesting
When I was younger I used to try to think out of the box
but after twenty five years of having that big shoe stomp my
head back in the box it's hard to think at all now.
On an air plane, or an air boat constant timing works,
but in an automotive application variable timing seems necessary
I'm going back in my box before the big shoe comes back.