4WD MODIFICATIONS - POWERTRAIN
The USA’s Environment Protection Agency (EPA) concluded a series of scientific tests on a wide variety of devices and additives that are claimed to improve fuel economy. Of the hundreds tested, very few actually reduced fuel consumption.
Of the six devices that worked without illegally increasing air pollutants, one was a spoiler system that made a vehicle more aerodynamic, three shut off power to accessories such as the air conditioner and the other two provided ways to decrease idling time.
Most of the products marketed fall into five basic categories: vortex generators that create swirling air flow in the air intake, magnets that strap around or connect into the fuel lines, air-bleed devices, fuel additives and oil additives.
High fuel prices cause many people turn to products or fuel additives that claim large gains in fuel economy, but none of the magic pills and potions, fuel line magnets or vortex generators works, according to test results from the EPA.
Magnets make your speakers function and provide detailed images of the human body, but they aren’t likely to save a cost conscious motorist any money at the gas pump, said EPA spokesman John Millett.
Vehicle owners would do better to change a few of their driving habits and make sure their vehicles are properly tuned and maintained, he said.
Claudia Bourne Farrell, a spokeswoman for the US Federal Trade Commission, said that the Commission has evaluated many products that claim to enhance performance and has not seen any that lived up to their claims.
So why do these products keep selling? Why do so many people swear by them while others are completely convinced they are scams?
‘Results May Vary’
All fuel economy ‘improver’ packages and labels have disclaimers that say ‘results may vary’, because of driving habits, vehicle type, vehicle condition and road conditions.
In that simple caveat lie the reasons why people can install a device or use an additive that does nothing to change fuel economy but can see an improvement in fuel economy after adding it.
Testing a product to determine if it has increased fuel economy requires an automotive laboratory with sophisticated equipment. The equipment is necessary to rule out the effects of different air temperature, humidity and road conditions that can cause fuel consumption to vary 10 or 20 percent.
Many fuel consumption ‘improvement’ device makers claim that their fuel-saving function is due to improved combustion quality, but in a modern 4WD engine that’s correctly tuned, less than one percent of the fuel that enters the combustion chamber isn’t burned. Maximising the burn further might lower emissions minutely, but would do virtually nothing for fuel economy.
Many people install vortex generators or magnets at the same time as they give their vehicles a tune-up, so the devices may get the credit for the improvement in fuel economy that really resulted from the tune-up.
Another reason for fuel economy improvements from using vane-type devices is that they actually restrict airflow. Popular Mechanics in the USA did dyno testing after they found a fuel economy improvement in some cases, using vane-type devices. However the dyno showed a commensurate drop in horsepower!
Less fuel equals less horsepower.
Real Economy Improvers
Regular servicing, maintaining correct tyre pressures and keeping your 4WD as streamlined as possible are the starting points for improved fuel economy.
A well-serviced 4WD rolls freely on lubricated and adjusted wheel bearings, doesn’t have dragging brakes and its engine is operating at its optimum, with clean oil, fresh plugs and/or clean injectors.
Tyres inflated to the 4WD maker’s recommendation roll with less resistance than under-inflated ones.
Don’t run heavily-blocked mud tyres unless you really need them. ‘Lug’ tyres have a huge influence on rolling resistance – we regularly measure at least a five percent fuel consumption difference between mud tyres and road types.
A roof rack increases drag and drag eats fuel. If you need your roof rack only once or twice a year, take it off and stow it.
Once you’ve taken these fuel economy steps, take a critical look at your driving style. If you don’t get high kilometres out of your 4WD tyres and brake pads you’re wasting fuel. Driving for economy means no hard-braking or hard-cornering.
Use anticipation when you’re driving, so you don’t need to brake hard to wash off speed and then have to build it up again.
Try cruising at lower speeds. It’s easy to measure the difference in fuel consumption if you cruise on the bitumen at 95km/h instead of 110km/h.
On dirt, knock your speed back to a more economical and safer 80km/h. In the case of the average diesel 4WD you’ll get at least a 10 percent fuel saving by slowing down.