Engineered Propulsion Systems Graflight V-8

The Graflight V-8 is a liquid-cooled, flat V-8 with steel pistons and compacted graphite iron crankcase for better strength and durability than aluminum at similar weight, increasing time between overhauls to 3,000 hours. It is managed by a Bosch ECU and can run on Jet A, JP-8 or straight diesel fuel. It is intended to be used in general aviation airplanes, small helicopters, military drones, small boats or troop carriers.[1] The engine is specifically targeting the Robinson R44, Beech Bonanza, GippsAero GA8 Airvan, Cessna TTx and Cessna 206 as possible applications.[2]

The design is a 320–450 hp (240–340 kW), 4.3-liter engine with steel pistons, connecting rods, and crankcase to improve reliability. At 650 lb (290 kg), it weighs 40 to 50 lb (18 to 23 kg) more than a conventional aircraft engine, not including the 30 lb (14 kg) radiator for cooling. It should be 30-40% more expensive to purchase than a comparable avgas engine, but with 30-50% better fuel economy.[3] Its low vibration levels allow the use of composite or aluminum propellers.[1]

The engine's 17:1 compression ratio gives it a best brake specific fuel consumption of less than 0.32 lb/(hp⋅h) (195 g/kWh), compared to typical avgas engines with 0.42 lb/(hp⋅h) (255 g/kWh). It is expected that the Graflight V-8 will burn under 11 US gal/h (42 L/h) of fuel at 65% power.[4]

As a direct comparison, the 350 hp (261 kW) version of the Graflight V-8 engine will weigh 30 to 50 lb (14 to 23 kg) more than the comparable Lycoming TIO-540-AE2A (595 lb (270 kg) dry) or Continental TSIO-550-E (498.4 lb (226.1 kg) dry). It will cost 30% more, but with a higher time between overhaul and lower fuel burn, it will have lower operating costs.[5] At normal 75% cruise power, the Graflight V-8 consumes 77 lb/h (35 kg/h) of fuel, whereas the Continental TSIO-550-E burns 110 lb/h (50 kg/h), a reduction of 30%.[6]

EPS set out to certify a new-design flat 8 engine, to replace existing 320–420 hp (240–310 kW) general aviation gasoline engines, with the aim of reducing fuel costs by 45%.[7] EPS started work on the design in 2006, a process that took five years.[3] The engine was first flown in May 2014,[8] first exhibited at the 2017 EAA AirVenture and FAA certification was expected at that time by the end of the year.[2]

Later in 2017 the testing progress was delayed by insufficient funding. By July 2018 it had completed 25 hours of flight testing on a Cirrus Aircraft airplane. At that point the company hoped to attract Fortune 500 investors and planned that a new demonstrator should be ready in the first quarter of 2019.[3] The production version of the engine was shown at AERO Friedrichshafen in April 2019 and work continued on environmental and block testing towards the goal of type certification.[8]

Unable to obtain the needed financing to continue operations, the company filed for Chapter 11 bankruptcy protection in August 2020.[8]

• Cirrus SR22

Data from EPS[1]

• Company website