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Engineered Propulsion Systems Graflight V-8

The Graflight V-8 is an aircraft diesel engine developed by Wisconsin-based Engineered Propulsion Systems

Graflight V-8
Type Water-cooled V-8 piston diesel aircraft engine
National origin United States
Manufacturer Engineered Propulsion Systems
Designed by Michael Fuchs and Steven Weinzierl
First run 2014
Major applications Cirrus SR22
Program cost $32 million[1]



It is a liquid-cooled 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 h. It is managed by a Bosch ECU and consummes Jet A, JP-8 or straight diesel for general aviation aircraft and small helicopters, military drones, small boats or troop carriers, and its low vibration allows the use of composite or aluminum airscrews.[2]

Its 17:1 compression ratio enables a best brake specific fuel consumption lower than 0.32 lb/hp/h (195 g/kW/h) while Avgas engines are at 0.42 lb/hp/h (255 g/kW/h), for under 11 US gal/h (42 l/h) at 65% power.[3] At 262 hp (195 kW), 75% of the 350 hp (261 kW) max, it consumes 77 lb/h (35 kg/h) where the Continental TSIO-550-E burns 110 lb/h (50 kg/h)[4]

The 4.3-liter, 350-horsepower engine will weigh 30 to 50 lb (14 to 23 kg) more than comparable Lycoming TIO-540-AE2A (595 lb (270 kg) dry, from $94,300) or Continental TSIO-550-E (498.4 lb (226.1 kg) dry, from $72,400) and it will cost 30 percent more, but with higher TBO and lower fuel burn it will have lower operating costs.[1] It targets the Robinson R44, Beech Bonanza, GippsAero GA8 Airvan, Cessna TTx and Cessna 206.[5]

Flat 8Edit

The 320–450 hp (240–340 kW), 4.3-liter, flat-8 horizontal piston engine still has 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 engine, not including the 30 lb (14 kg) radiator. It should be 30 to 40% pricier than a comparable avgas engine but with 30 to 50 % better fuel economy.[6]


EPS started in 2006 and designing the basic engine took five years.[6] The engine was exhibited at the 2017 EAA AirVenture and FAA certification was expected by the end of the year.[5] In 2018, EPS was going to certify a Flat 8 engine, to replace 320–420 hp (240–310 kW) general aviation gasoline engines and reducing fuel costs by 45%.[7] After testing was slowed by insufficient funding in 2017, it has been tested for 25 hours on a Cirrus Aircraft by July 2018 and future investors may include a Fortune 500 company while a new demonstrator should arrive in the first quarter of 2019.[6]


Graflight V-8


Specifications (Graflight V-8)Edit

Data from EPS[2]

General characteristics


  • Fuel type: Jet A, JP-8 or straight diesel
  • Cooling system: liquid cooled


  • Power output: 350 hp (261 kW)
  • Compression ratio: 17:1
  • Fuel consumption: 9.74 to 17.55 US gal/h (36.9 to 66.4 l/h) from 210 to 350 hp (157 to 261 kW)
  • Specific fuel consumption: 0.315 to 0.34 lb/hp/h (192 to 207 g/kW/h)


  2. ^ a b "Engine Overview". Engineered Propulsion Systems.
  3. ^ "EPS Making Progress on Certification of Vision 350 Flat-V Diesel Aero-Engine" (Press release). EPS. Jul 9, 2013.
  4. ^ "Fuel Economy". Engineered Propulsion Systems.
  5. ^ a b Pia Bergqvist (July 7, 2017). "EPS Diesel Engine Nears Certification". Flying Magazine.
  6. ^ a b c Mark Huber (July 25, 2018). "EPS Continues To Make Progress on Aero Diesel". AIN online.
  7. ^ Addison Schonland (March 26, 2018). "EPS Diesel Progressing Toward Certification". AirInsight.

External linksEdit