The company is using Honda L15-series and Mitsubishi car engines for their conversion to an aircraft application. You may buy them new from Honda but most customers opt for used engines that have been used in cars for less than six months or 5000 miles. After they leave the Viking factory assembly line they can be considered as a rebuilt/new aircraft engine.
The result of this hard work is an engine with the latest technology for the lowest price available. The fuel economy is world class; the power to weight ratio is superb. The quality of the engines is as good as Honda gets it and to ensure reliability, Viking performs dynometer testing combined with thousands of hours of in flight testing.
Below you will find the installation and operations manual for the former Viking 110 engine.
Credit: Viking Aircraft Engines inc.
Excerpt from the document:
The Viking Aircraft Engine is experimental in nature and should be viewed as such. The suitability of the engine for any particular application should be determined by the builder or operator.
The Viking YouTube video series has gone into great detail regarding proper practices for wiring, plumbing, etc. Rather than to replicate all of that information, we will instead focus solely on the installation procedures.
To continue reading see the pdf below: