I got an email from Viking Aircraft Engines announcing their new Viking 90 engine.
It sounded interesting because it makes 90HP and weighs only 10lbs more than the Rotax 912.
I like the affordability concept of using automotive engines for aircraft and I probably would have bought
a Viking but the Viking 110 and 130 were both a little heavy for the Searey.
I was wondering where this engine came from. Credit to my building partner Ethan for doing some quick internet research as it doesn’t give a lot of details on the Viking website yet.
https://www.vikingaircraftengi nes.com/viking-90-hp-engine. html
What it does say is that it is a “1.2L mivec dohc 12-valve 3-cylinder” engine
If you google that term the first search result is the 3 cylinder engine used in the Mitsubishi Mirage.
Checking the details, the bore, stroke, displacement, compression ratio all match up to the Viking 90.
The 3A92 engine used in 2012-present Mitsubishi Mirage GL, GLX, GLS, GLS, and LTD models
This engine is sold as Mitsubishi Space Star in Europe and Singapore, Attrage/Mirage G4 in the US, and Dodge Attitude in Mexico
Here are some engine pics:
http://mirageforum.com/forum/s howthread.php/24-3A92-1-2L-3-c ylinder-Mirage-Space-Star-engi ne-info-(specs-specifications)
Ethan observed that the fancy MIVEC technology is a fairly sophisticated VVT system that does not offer many advantages in an aircraft engine, where most of the operation is steady-state over a fairly narrow RPM band, and emissions are not regulated
http://mirageforum.com/forum/s howthread.php/72-Video-New-MIV EC-continuously-variable-valve -control-mechanism
Ethan also theorized about the horsepower difference. The factory engine is 74 hp at 6000 rpm, with a 74 ft-lb torque-band from 3000-5000 rpm. This engine is quoted as 90 hp at 6,000 rpm (20% more than the factory) and 74 ft-lbs at 4000 rpm (exactly the same as the OE). Some of the gain is probably from running at a max-power rich air:fuel ratio in the 12:1-13:1 range, instead of the minimum-emissions stoichiometric air:fuel ratio of 14.6:1 required for emissions-regulated on-road passenger-car engines. It may have also required a change to a cam that is more suitable to sustained high-speed operation, perhaps even one that is incapable of idling, but using the variable-profile capabilities could have a second profile just for idle.
Kudo’s to Viking for coming out with what looks like a nice engine in this horsepower/weight range!