Hybrid cars are already some of the most fuel-efficient vehicles on the road, but is it possible to make one burn even less fuel? According to internet lore, building your own hybrid turbo is the key to unlocking even greater fuel efficiency. You know what the Motor MythBusters have to do now: Find a hybrid car (like this 2011 Honda CR-Z), bolt a turbocharger to it, and find out if forced induction can increase fuel efficiency.
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The Motor MythBusters couldn’t be in better hands when it comes to making a hybrid turbo; Bisi Ezerioha bolts turbochargers to nearly any car imaginable (1,000-hp Honda Odyssey, anyone?) at his performance shop and consulting firm, Bisimoto Engineering. With the help of his Motor MythBusters co-hosts—Faye Hadley and Tory Belleci—the team should have no problem proving whether or not turbocharging a hybrid car can increase its fuel efficiency.
How Does a Hybrid Car Work?
In the case of the Motor MythBusters hybrid turbo candidate, the 2011 Honda CR-Z has a flywheel electric motor sandwiched between its 1.5-liter inline-four cylinder gas engine and the transmission (six-speed manual or CVT, the Motor MythBusters have the manual). The electric motor is powered by a high-voltage DC system, separate from the rest of the CR-Z’s 12-volt electronics (your stereo and interior lights and stuff).
When the Honda’s computers detect the need for a bump in power, the electric motor will engage and boost the gas engine’s power—aiding in climbing hills, accelerating onto highways, and so on. When the CR-Z is cruising steadily and doesn’t need much power to move along, the gas engine will shut off completely and the electric motor will provide all the necessary motive force.
The system works in reverse, too. When the brakes are applied or when the Honda is cruising steadily, the electric motor acts as a generator—using the CR-Z’s forward momentum to recharge the DC battery pack. Some hybrid and electric cars have such strong battery regeneration designed into their systems (like the BMW i3), the brakes don’t need to be applied in regular driving conditions to bring the car to a stop; the engine-braking effect of the electric motor in generator mode is enough to stop the vehicle.
In most cases, hybrid cars are more fuel efficient than their internal-combustion-only counterparts because the addition of the electric motor allows the internal-combustion engine to work less by picking up the slack where necessary, or take over entirely. Less work for a fuel-burning engine (obviously) means less fuel burnt and thus more efficiency, but hybridization is only a recent example of increasing fuel efficiency in cars.
Increasing Performance and Efficiency With Turbocharging
Forced induction on internal-combustion engines goes back nearly as far as the internal-combustion engine itself; Gottlieb Daimler patented a gear-driven air pump in 1885. But auto manufacturers didn’t start embracing forced induction on production cars until nearly a century later, when the OPEC oil crisis started the trend of decreased displacement and increased fuel economy.
Coming on the heels of the muscle-car era, enthusiasts were left wanting with the disappearance of high-powered V-8s, but manufacturers attempted to fill the gap with turbochargers. Throughout the 1960s, ’70s, and ’80s, manufacturers learned they could build reliable, small engines that made as much power as the larger muscle-car-era V-8s, while keeping up with federal demands for fuel efficiency.
Turbocharging has become such a popular and efficient option, some manufacturers are doing away with large-displacement, naturally aspirated engines as their premium options. For example, look at the best-selling vehicle in the world: the Ford F-150. You’re thinking, Big American pickup truck, big American V-8, right? Wrong, sort of. While there is still a V-8 option available in the F-150, the ruler of the roost is the 3.5-liter twin-turbocharged EcoBoost V-6.
Available in F-150s and spreading throughout the Ford fleet since 2011, the 3.5-liter EcoBoost V-6 makes as much power as a 5.0-liter V-8, while being up to 25 percent more fuel efficient. In top F-150 Raptor trim, the 3.5-liter EcoBoost V-6 makes 450 hp and is good for 18 mpg—might not sound like much, but when that’s coming out of a 5,500-pound race truck, that’s not bad. It’s even better in the full-size Lincoln Navigator SUV that gets over 20 mpg with the same drivetrain. Trucks like these were hovering in the low-teens for fuel economy—single digits when hauling any sort of weight—as little as 10 years ago.
Then you have even smaller EcoBoost engines like the 2.3-liter EcoBoost turbo inline-four in the Ford Ranger (it’s in the Mustang, too). Good for nearly 300 hp and 26 mpg, the current generation of Ford Ranger is more powerful and fuel efficient than ever, thanks to turbocharging. Ford’s range of turbocharged EcoBoost engines are some of the most efficient in the world, while maintaining enthusiast-pleasing horsepower-to-displacement ratios.
Turbocharge Your Hybrid Car
A turbocharger allows small-displacement engines to make more power than they would be capable of without forced induction, but forcing more air into the combustion cycle of a gas engine doesn’t immediately equal more power. More fuel must go in at the same time to keep the engine from running too lean and damaging the engine.
Small turbocharged engines can make as much power as larger naturally aspirated engines while consuming less fuel, but comparing a turbocharged engine with a naturally aspirated engine of the same size may not have the same effect. The Motor MythBusters may have increased the power of their 2011 Honda CR-Z with a turbocharger, but how does that affect the fuel efficiency? Find out by subscribing to the MotorTrend App and watching the latest episode of Motor MythBusters.
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