Golf Course Management magazine is dedicated to advancing the golf course superintendent profession and helping GCSAA members achieve career success.
Issue link: http://gcmdigital.gcsaa.org/i/234582
Scott R. Nesbitt ORPguy@windstream.net (shop) Replacing a damaged carburetor with electronic fuel injection makes no sense economically, but would be an interesting tinkering project. The inset picture shows a throttle-body fuel injection nozzle for an engine three times larger than the typical V-twin gasoline engines found on turf equipment. Photos by Scott Nesbitt Retroft EFI: is it worth consideration? With electronic fuel injection (EFI) replacing carburetors on air-cooled engines powering some new turf equipment, daring souls may think about converting older carbureted engines to the modern computer-controlled engine management system. Unless you have time to tinker and a big budget, chances are you're better off waiting to replace old equipment with new machines that start life with EFI engines. Conversion is for hobbyists. Check Youtube.com under "EFI small engines." Is EFI that much better? Yes. Cars and trucks have used EFI for 25 years, achieving improved fuel economy, reduced emissions, improved engine life and increased reliability. Gone are the fooding and vapor-locking that marred my youth. Motorcycles, particularly the small one-cylinder Asian "monkey bikes," have seen increasing use of EFI to improve power and reduce emissions. Some of the cycle EFI components end up on experiments seen on YouTube. Turf mowers with EFI engines have been in limited production for more than 10 years. The learning curve is suffciently fat now, and several mower makers offer the technology. Cars and cycles have a throttle directly controlled by the driver. Turf equipment engine speed is controlled by a governor, and that's a big difference. On-road EFI technology doesn't 34 GOLF COURSE MANAGEMENT 01.14 directly translate, or trickle down, to the turf small engine market, and that slowed introduction of EFI for the green industry. On a carburetor-governed engine, you select a desired engine speed by stretching a spring, which pulls the throttle wide open. When the engine comes up to speed, centrifugal force from the governor's spinning fyweights counteract the spring, pushing the throttle closed. No road vehicle has to deal with the continual schizophrenic push-pull mechanical throttle-fuel-timing balancing process found in a mower engine bouncing across the rough. With EFI, engine speed is read directly off the fywheel by a magnetic pickup sensor. The data instantly feed the electronic control unit (ECU), which adjusts fuel fow, throttle position and ignition timing to maintain engine speed. The ECU also processes data on incoming air temperature and density, and engine temperature. Drive an EFI mower and you'll notice the greatly reduced engine "droop" when it hits a load. With carburetion, acceleration is achieved by dumping a "best guess" amount of extra fuel into the intake air stream. With "closed loop" EFI systems, there's an oxygen sensor in the exhaust system. This detects unused oxygen (lean condition) or unburned fuel (rich condition) and adjusts the fuel injection rate to maintain an "ideal" air-fuel ratio. Acceleration uses a small dose of extra fuel that's quickly reduced based on the oxygen sensor. The net effect is that EFI engines use about 25 percent less gasoline. Currently, Kohler is the leading air-cooled EFI engine maker. The engines show up mostly on zero-turn mowers, the largest single segment of the commercial turf market. Competing engine makers should be on the market soon, and the range of EFI-powered machines should rapidly expand. You'll pay a premium for EFI on a new machine. You should make it up in fuel savings. And internal engine wear should be reduced, because EFI reduces instances of excess gasoline washing oil off the cylinder walls, and ending up diluting the crankcase oil. Here's an example to put price into perspective: We have a 14-horsepower 7,000-watt generator with a water-damaged carburetor. Heroic efforts are needed to get it started and keep it running. A $70 rebuild kit would not likely repair the damage. A new carb runs about $200. For about $300 there's a kit that converts the generator to run on propane — we could tap the propane tank that serves the house, and have backup electrical power. We could spend about $700 to $900 for a kit to replace the carburetor with an EFI system. For that price, we could buy a new generator with equal power output. I think we'll wait. Scott R. Nesbitt is a freelance writer and former GCSAA staff member. He lives in Cleveland, Ga.