The engine downsizing trend sweeping across the global powertrain community need not apply exclusively to hulking V-8s and high-powered V-6s.
No, even 4-cyl. engines can be squeezed for higher efficiency, and powertrain engineering specialist FEV Inc. has developed a 0.7L turbocharged 3-cyl. engine concept intended to replace powerplants twice its size.
Simply named Extremely Downsized Engine, the direct-injection gasoline concept delivers 134 hp/L and is capable of 12% better fuel efficiency than a naturally aspirated 1.5L 4-cyl., says Henning Kleeberg, FEV’s department manager-spark ignition engines.
On display for the first time in the U.S. at the recent SAE World Congress in Detroit, the EDE concept arrives in anticipation of stringent new emissions mandates in Europe and the U.S.
The European Smart car’s high-performance Brabus engine, with two spark plugs per cylinder and conventional port fuel injection, serves as the base for the 0.7L concept.
To boost efficiency and power, FEV replaced PFI with direct injection and removed one of the spark plugs in a significant redesign of the head.
“As we go to smaller combustion chambers, the challenge is to get direct injection in there, to get the fuel mixed and to get away from the low-speed pre-ignition problem that DI engines have,” Kleeberg tells Ward’s.
So the reconfigured SOHC valvetrain incorporates a longer camshaft and dual independent cam phasing, allowing for fully variable valve timing and overlap on both the intake and exhaust ports, with a control valve for each.
FEV collaborated with fellow suppliers Mahle GmbH and Hydraulik-Ring GmbH on the valvetrain, which has two valves per cylinder.
Without the ability to phase between two cams on the same shaft, the EDE concept would lack low-end punch.
“It’s very critical for a downsized concept,” Kleeberg says. “We have the same low-end torque as with a larger naturally aspirated engine. With the large valve overlap, you can create quite significant torque improvement at low speeds. That’s what the driver feels when he steps on the pedal.”
The small turbocharger allows for rapid spool up of inertia, which further helps overcome the typical sensation of “turbo lag.”
Compared with a naturally aspirated 1.5L 4-cyl. typically found in subcompacts, this concept delivers 32% more torque at only 1,500 rpm, Kleeberg says.
The concept delivers 100 hp for an impressive specific output of 134 hp/L, as well as 103 lb.-ft. (140 Nm) of torque.
With a bore diameter of 66.5 mm (2.6 ins.), FEV says the EDE would be the smallest powertrain in the market; it also is compatible with a hybrid-electric configuration.
FEV says the concept engine would be ideal for European vehicles in the B and C segments, as well as B-segment cars in the U.S.
There are cost benefits, as well. Removing a fourth cylinder and related hardware means material costs can be cut by a quarter.
Even after adding cam phasing, direct injection and turbocharging, Kleeberg says he believes the system is cost-competitive, but a cost analysis has not been completed.
He hopes American drivers accustomed to V-6s and V-8s can keep an open mind to 3-cyl. engines. “It sounds scary maybe to go to something below 1.0 L, but if you look at how the market has changed here over the last two to three years, everyone is downsizing.”
Gary Rogers, president and CEO of FEV, is optimistic about finding a customer to adopt the EDE concept.
“The question in many people’s minds is, how low can you go? At what point does (downsizing) no longer make any sense?” Rogers tells Ward’s. “If you want to get into another 15% fuel-economy improvement without hybridization and the cost of batteries and all that, another step on the path that you can go is yet smaller.”
FEV also is shopping an electrically assisted 7-speed automated manual transmission intended for hybrid-electric vehicles.
Designed for transverse applications, the transmission is equipped with an electric motor designed to eliminate torque interruption, a major disadvantage of automated manuals, even in high-end sports cars.
FEV’s approach is to provide two independent torque paths, one for the internal-combustion engine and one for the electric motor. While accelerating, the gasoline engine is running, but gear shifts with automated manuals often create a long pause between gears.
With FEV’s concept, an electric motor delivers a surge of power during shifts to fill the torque gap.
Rogers describes the driving feel to that of a continuously variable transmission, which does not shift gears.
There is no torque converter. Instead, a single clutch is electrically actuated. Rogers says the transmission can accommodate 288 lb.-ft. (390 Nm) of torque between the engine and electric motor.
FEV has a customer for the transmission, but Rogers declines to identify the auto maker. A drivable prototype is on the road for a European auto maker, and another is being developed for North America.
Rogers says the transmission is affordable and ideal for front-wheel-drive B- and C-segment vehicles. Leading research for the program was FEV’s Hybrid-Electric Vehicle Development Center in Auburn Hills, MI.