Properly tuned modern forklift engines with the latest emission controls can operate without loss of performance, according to North American industry experts. Roger Renstrom reports after a recent Forkliftaction.com News discussion forum on fuel efficiency raised questions about the connections between emission controls and engine performance.

"Companies have to deal with this problem," says David Petrali, vice president of testing operations for USAC Properties, a subsidiary of the United States Auto Club in La Verne, California. "They do not have a choice" as emission standards tighten on forklift trucks.

Electronically controlled carburetion systems can regulate the richness of the fuel and can improve fuel economy, Petrali says. If computer controls sense too rich a mixture, they will try to compensate.

Engines "do not want to run too lean," he says. "Then you get compromises you do not want to see, and that can become extremely expensive" for the forklift owner.

USAC, an independent testing organisation, specialises in the design and implementation of tests for products relating to automotive, forklift and related industries.

A Canadian manufacturer of catalytic emission control products has not detected variances with controlled engines.
"Based on our customers' results, engine power output generally rises 5% to 10% if the engine calibration is done properly," says Wayne Borean, who handles major account sales for Nett Technologies Inc in Mississauga, Ontario. "Controlled engines generally run richer than uncontrolled engines, and the [engine control unit] keeps the air/fuel mix near optimum."

Borean says he has not seen any drop in engine performance with an exhaust-pollution-controlled engine.

Borean was asked whether tougher emission controls make engines work harder and consume more fuel to do a job. "No, usually the fuel consumption remains the same or drops marginally," Borean says. "I've never seen a controlled engine that used more fuel than an uncontrolled engine unless the customer was running the uncontrolled engine really lean, which means less power and tends to burn out valves and pistons."

Controls can cause some problems but none that would indicate environmental controls are counterproductive, Borean says. "Controlled machines don't work well on mountains. Anything higher than 5,000 ft (1,500 metres) could be an issue because the ambient air pressure is lower, which can throw off the control."

Borean notes that some manufacturers have introduced "fixes to minor calibration issues". Such environmental controls have improved engine life and power while keeping fuel economy about the same and reducing carbon monoxide emissions by 90% or more. "Who wouldn't like that?" he asks.

Andy Suhy, director of product development with Power Solutions Inc (PSI) of Wood Dale, Illinois, says: "Emission controls have improved the standard of performance for off-highway engines while lessening the impact that off-highway engines have on the environment. Emission regulations and subsequent controls have improved engine performance by forcing engine companies to develop automotive quality level fuel systems that are durable over the emission useful life period."

Suhy says emission-certified engines run hotter due to leaner air-fuel ratios required to meet the emission standards. "Emission-certified engines generally have better fuel economy, compared to previously non-certified engines, due to better air-fuel ration control," he says.

A major distributor and supplier of General Motors Corp industrial engines, PSI provides power solutions involving cooling packages, fuel systems, air handling, hydraulics, electrics, packaging, telematics, certification and emissions compliance and design services.

Electronic fuel control systems have improved the performance of liquefied petroleum gas (LPG) forklifts marketed by Toyota Material Handling USA Inc (THMU) of Irvine, California.

"Thanks to new technology, emission controls have no negative impact on an engine's performance," says Mark Hartman, assistant manager of product planning and support for TMHU internal combustion engines.

Improvements in power, fuel efficiency and emission reduction "can be attributed to the use of new electronic fuel control systems," Hartman says. "These systems control the engine's air-fuel ratio more precisely than the old mechanical systems. The old mechanical systems had to be designed to estimate the amount of fuel the engine needed. The new systems use multiple sensors to provide close to the exact amount of fuel necessary for a particular engine."

Achieving power and fuel efficiency requires precision.

"The ideal air-fuel ratio is where all of the fuel is burned in the engine during combustion, and there is no air left over," Hartman says. "If the fuel system provides too little fuel, the excess air will be wasted (lean condition), and the engine will not reach its full power potential. If the fuel system provides too much fuel, the excess fuel will be wasted (rich condition), and the engine will be inefficient."

Achieving the ideal is difficult "due to current technology and impurities in the fuel, but the new electronic fuel systems are much closer than old mechanical systems," Hartman says.

The ideal ratio is also important in regulating emissions. All current spark-ignited lift trucks must be equipped with emission systems in order to meet the current US Environmental Protection Agency and California Air Resources Board emission standards, Hartman says. "Catalytic converters operate best at or near this ideal air-fuel ratio. For example, Toyota's LPG lift trucks equipped with electronic fuel control systems effectively reduce emissions by as much as 95% compared to lift trucks sold five years ago."