Assuming everything else is equal (vehicle size, weight, driving style, tires), how do you make ICE engines be more fuel efficient? I noticed my dad’s 1996 Nissan Pathfinder V6 consumes 13L/100km (mixed driving) while a newer V6 is 9L/100km. Car manufacturers claim their engines are “more fuel efficient”, how do they accomplish that?
In: 85
3 ways- advancements in technology, lighter vehicles and aerodynamics
Technology regarding fuel injection means the engine can be more efficient. Direct injection lets you inject fuel directly into the combustion chamber (hence the name, right?), and this results in a more complete burn and the ability to fine tune exactly how much fuel goes into the cylinder. The more complete combustion means there’s less wasted energy in the form of heat, so a higher compression ratio can be used, which will deliver a little more power and (usually) a small bump in fuel efficiency. Direct injection is often paired with turbocharging, and having a turbocharger lets manufacturers use a smaller engine but produce the same, or often more, power. Smaller engine running low or no boost means more fuel efficiency. Variable valve timing is a common way to increase fuel economy and power- by being able to hold valves open longer, and control their overlap, but if you’re holding them open longer you’re drawing in more air and increasing efficiency. Cylinder deactivation is exactly what it sounds like- at a steady speed with no load or minimal load, the engine will shut down one/multiple cylinders. That v8 just dropped 4 cylinders, and now is running on just 4. Less fuel is used, mpgs are increased
Vehicles are being made lighter and lighter- either from lighter metals like aluminum, plastic bumper covers, or just less material (your frame is a good example of this). Dropping 5-10 pounds here or there adds up, and when everything is combined the effect can be dramatic. A god example of this is ford switching to high strength steel and aluminum for the 2015 f150, and making the supercrew trucks about *700 pounds* lighter than the same supercrew truck was in 2014.
Aerodynamics will, of course, play a part as well. Having o push a vehicle through the air takes effort, which requires power, which needs fuel. Little things can add up here as well- you’ll notice most modern vehicles have air lips/dams on the front, some even have motorized ones. The less air that goes under the vehicle, the less drag it has underneath. Panels are made to redirect air more efficiently, even the rear of trucks are designed to create a low pressure zone behind them, you can see this with little lips, almost like a small built in spoiler, built into the tailgate design. Ford has slots above the front bumper to redirect airflow to the sides instead of having it just smash into the front. Many vehicles now have active grille shutters, which open or close and can effect airflow as well.
Sounds kind of complicated, right? Now combine them all, and is no wonder we can get some decent fuel economy numbers if we drive modern vehicles correctly. This isn’t even including things like stop/start, or gearing, or adding more gears into the transmission. And obviously this isn’t true across the board, but it gives you a little bit of an idea
Latest Answers