23 July 2025
In another massive surprise from this year’s EAA AirVenture Oshkosh event, Piper Aircraft announced the Florida manufacturer is to fit its Seminole light twin with a pair of 180hp DeltaHawk diesel engines.
The liquid-cooled, turbo-charged DeltaHawk engine is said to produce turbine performance at 40% better fuel efficiency versus reciprocating avgas engines, while also achieving a significant reduction in cost of ownership due to fewer moving parts.
The engine is approved for Jet A and Jet A-1 fuels, with Sustainable Aviation Fuel (SAF) approval pending.
Piper will use a Piper-owned STC to integrate DeltaHawk’s firewall-forward kits into the Seminole production line. The kit includes counter-rotating DeltaHawk engines and three-blade, full-feather propellers.
Additionally, the aircraft will have an advanced cabin temperature control system utilizing the engines liquid cooling to ensure a comfortable flight experience in diverse conditions.
“The market has been heard, loud and clear regarding the need for a reliable, cost-effective, heavy fuel, multi-engine training platform,” said John Calcagno, President and CEO of Piper Aircraft.
“The new Seminole DX fills that market void perfectly. We anticipate global market demand for the Seminole DX to be between 25 to 40 aircraft per year over the next 10 years.
“The DeltaHawk team has been a pleasure to work with over the past 16 months as they epitomize quality and customer focus. Future collaborations are in process as well.”
A 20-year Long Term Supply Agreement (LTSA) designates DeltaHawk as the exclusive heavy fuel, piston engine supplier for the Piper Seminole. Certification flight testing begins in November 2025, with FAA certification expected in Q3 2026, followed by certifications from Transport Canada, EASA, and India’s DGCA.
Deliveries of 2027 model year Seminole DX aircraft are anticipated to begin in late 2026 or early 2027.
“The installation of our certified DHK engine in the legendary Piper Seminole is a perfect match with our industry-unique features to provide the lowest cost of ownership and the simplest and safest multi-engine training platform ever,” said Christopher Ruud, Chief Executive Officer of DeltaHawk Engines.
“Just as important, we see this new 20-year agreement not just in terms of engines, but also as a wonderful step by Piper, utilizing DeltaHawk’s powerful innovation, while creating environmental sustainability for general aviation worldwide.”
Piper said the Seminole DX offers significant performance enhancements over the current PA-44 Seminole, including a 35% reduction in fuel burn, a 32% increase in single-engine climb rate, and a 70% higher single-engine absolute ceiling.
Piper Aircraft
Introducing the Piper Seminole DX, the next evolution in multi-engine training in partnership with @DeltaHawkEngine pic.twitter.com/zxUzCfxUO3
— Piper Aircraft, Inc. (@piperaircraft) July 22, 2025
DeltaHawk Engines received FAA Type Certification for its 180 horsepower DHK180 in 2023 and say it is the first of a family of engines.
The DHK180 has an inverted-V engine block, turbocharging and supercharging, mechanical fuel injection, liquid cooling, direct drive, and 40% fewer moving parts than other engines in its category. It’s a clean-sheet design secured by multiple patents.
DeltaHawk says the engine is highly responsive and produces more usable torque than traditional aircraft engines in its class, while burning significantly less fuel – which is Jet A1, more easily available especially outside the US.
In addition, the engine’s slimmer shape and smaller size allows for more aerodynamic cowling designs and requires less space.
“We began by completely reimagining what a general aviation engine should be,” said Christopher Ruud, Chief Executive Officer at DeltaHawk.
“And the result is that we now have a certified engine that is a game-changer. It’s been a long time coming but, in engineering, simple is hard. However, this engine’s performance, simplicity, and reliability have made it worth the time and the investment.”
