caption. Click image to enlarge
By Jim Kerr
Achieving good fuel economy isn’t accomplished with a magic spell, add-on gimmicks or a mystery carburetor, although there are some out there who would have you believe otherwise. Good fuel economy is achieved by attention to details, good engine design and having the right combination of drivetrain for the vehicle. Let’s look at a few things manufacturers are doing currently to increase their fuel economy ratings.
The new Hyundai Santa Fe is a good example of what technology can do. The new 2010 model gets a larger 3.5 litre V6 engine, up from 3.3 litres, and it puts out 274 horsepower, up from 242 in last year’s model. With those numbers, you would expect the engine to use more fuel but it doesn’t. Instead, it gets 14 per cent better fuel economy.
Variable cam timing is one of the things used to achieve this, a technology common to many vehicle manufacturers. The car’s computer uses solenoids to direct oil pressure to an advance mechanism on the drive end of the camshafts that will move the camshafts back and forth in relation to the crankshaft position. It isn’t as complicated as it sounds. Advancing the camshaft will give the engine more low rpm torque, while retarding its rotation will provide more high-rpm power. By tailoring the power output to the demands of the driver at any engine speed, the engine can put out more power and get better fuel economy.
Variable intake tuning is another technique used by many manufacturers. Some use butterfly valves to partially block intake airflow at times. Others use dual intake runners, where one runner for each cylinder can be turned off, and others use a valve that separates two halves of a manifold at certain rpm and connects them together at other rpm Regardless of the method, the purpose is all the same – to maximize air velocity into the combustion chambers. With the computer tuned to open or close the manifold valves or plates at select engine speeds, the high velocity air picks up the fuel from the injector tips and swirls the mixture in the cylinder so it burns completely and cleanly.
Reducing engine internal friction has been an ongoing goal. Low tension piston rings, shorter piston skirts, roller lifters and roller timing chains are all parts used to reduce parasitic drag. Another way of reducing friction is to use oil that flows easier. Many manufacturers are beginning to use 0W-20 Synthetic oil for its low friction qualities yet it still protects at high heat and loads. Toyota has been using 0W-20 synthetic oil in many of their vehicles as a “factory fill” for several years!
The use of more transmission gears has enabled engines to operate in more efficient ranges. Six-speed manual and automatic gearboxes are now very common. So is electric power steering, which eliminates the parasitic drag of a drive belt and hydraulic oil pump. Electricity is used only when the steering is being turned.
Controlled charging system rates are another fuel saving technology. There are many electrical accessories on our vehicles, so high output alternators are needed to provide power to them all. However, we don’t need all that power all the time. With computer control of charging systems, there are now many times with the system is fully turned off and then cycled back on again when the battery voltage drops or we place an electrical load on the system. With the charging system off, there is very little parasitic drag on the engine and fuel economy increases.
BMW was the first manufacturer to use a factory installed electric waterpump but now we are seeing them used often on hybrids and some conventional vehicles. The computer controls the speed of the pump so coolant is only circulated when it is needed instead of all the time as with a belt-driven pump.
Direct fuel injection will also improve fuel economy by 15 to 25 per cent over a port injection engine. Parts are more expensive, but mass production is lowering the costs and this system is becoming common. For owners, the additional cost is quickly paid for in fuel savings.
While the manufacturers are using many ways to improve fuel economy, driving style and speed still have a huge impact. You may not be able to convert your existing vehicle to these new technologies, but you can save fuel money with a smooth driving technique and keeping to those speed limits.