Interesting new Viking 90 Engine

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.
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:

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

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!

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