GAMI Research May Explain Valve Seat Recession With 94UL Avgas | Aero-News Network
Aero-News Network
RSS icon RSS feed
podcast icon MP3 podcast
Subscribe Aero-News e-mail Newsletter Subscribe

Airborne Unlimited -- Most Recent Daily Episodes

Episode Date

Airborne-Monday

Airborne-Tuesday

Airborne-Wednesday Airborne-Thursday

Airborne-Friday

Airborne On YouTube

Airborne-Unlimited-02.10.25

Airborne-NextGen-02.11.25

Airborne-Unlimited-02.12.25

Airborne-AffordableFlyers-02.13.25

Airborne-Unlimited-02.07.25

Tue, Aug 06, 2024

GAMI Research May Explain Valve Seat Recession With 94UL Avgas

Data Support Plausible Mechanism in Certain Lycoming Engines

General Aviation Modifications, Inc., (GAMI) announced at EAA AirVenture that after performing extensive testing of 94UL avgas in a Continental IO-550 engine operating at the equivalent of 73% power, the data indicated moderate to severe detonation that was absent when operating with 100LL.

The detonation observed with 94UL provides a reasonable explanation of the cause of valve seat recession reported in Lycoming engines in the training aircraft at the University of North Dakota (UND).

George Braly, GAMI’s Head of Engineering said, “It’s not the lack of lead in the fuel, it’s the lack of octane needed by those high-compression engines with advanced spark timing. This, at least, is a competent cause for the reported issue.”

Lycoming noted that its R&D has not yet definitively determined the cause of the issue, but suggested the higher aromatic content of the Swift 94UL fuel is being investigated as a contributing factor. 

However, GAMI tested a wide range of high octane formulations during development of its G100UL, some of which had aromatic content well above the 18-20% reported by Swift.

GAMI’s detonation test data noted above was obtained during operation of a Continental IO-550 engine with 8.5:1 compression ratio and spark timing set at 22 degrees before top dead center (DBTDC) running at 73% power and mixture set at peak EGT consistent with the operating procedure at UND. Tests performed under those conditions showed no detonation while running on either 100LL or G100UL, but after switching to 94UL significant and continuous detonation exceeding limits was observed.

FMI:  gami.com/

Advertisement

More News

Aero-News: Quote of the Day (02.09.25)

“We are very pleased to enter into this MoU agreement with Gogo, especially as we aim to offer our Airbus ACJ operators and business leaders the highest standard connectivity>[...]

ANN's Daily Aero-Linx (02.09.25)

Aero Linx: Rhode Island Pilots Association (RIPA) The Rhode Island Pilots Association represents the GA community based at seven airports in the State of Rhode Island. Our mission >[...]

Airborne-Flight Training 02.06.25: AeroEducate, Mil KingAirs, PilotWorkshops

Also: Lufthansa Dreamliner Sim, ATC Can't Quit, NBAA Leadership, Acting FAA Head ierra Space is becoming the newest content provider for EAA’s AeroEducate online resource and>[...]

Airborne 02.05.25: No Outs 4 ATC, Sporty's Acquires, 'Black' Boxes

Also: NOTAM System Restored, Textron Mil Trainers, Axiom Space, Police Rescues Cirrus Pax The Trump administration’s attempt at downsizing the federal workforce has run into >[...]

Airborne 02.03.25: Drone Pilot Bust, New Acting FAA Boss, PNE Lear Accident

Also: 2 Blimps For OSH, USCG-Airbus Deal, Japan Buys T-6s, Starliner Boss Replaced A 56-year-old California man recently pled guilty after he flew his drone into a Super Scooper fi>[...]

blog comments powered by Disqus



Advertisement

Advertisement

Podcasts

Advertisement

© 2007 - 2025 Web Development & Design by Pauli Systems, LC