Kiekhaefer Aeromarine Motors, of Fond du Lac in Wisconsin was the manufacturer of the famous Mercury inboard and outboard motors and snowmobiles.

-The Kiekhaefer engines are in fact Mercury outboard or snowmobile engines, sometimes named Kiekhaefer-Mercury as Carl Kiekhaefer was its founder and owner.

-This is mainly about adapted Mercury engines. Like the 2-stroke, 433 cc engine with two air-cooled cylinders giving 40 HP. Known as the Kiekhaefer Aeromarine Engine.

There is a snowmobile engine adapted for aviation, initially planned for the BD-5 aircraft.

-We obtained an image of an in-line twin-cylinder Kiekhaefer engine. It was fan-cooled and had CDI as iginition system.

“Kiekhaefer, Twin 440 model”

-The 440 gives 40 HP for a weight of 72 pounds including the fan system. Interestingly, there is a 30 mm output shaft with a 10° cone.

-The 2-cylinder Kiekhaefer that gives 40/55 HP, Model KAM 525.

-The V-105-2 model was used in 1953 on a target drone.

-The 80 hp Kiekhaefer Mercury was lowered to 56 hp for its use on the DelMar DH2 helicopter, with 6 horizontal cylinders. Add to outboard engine adapted by Kiekhaefer. (See Keickoffer, they are different, but easily confused).

-At the San Diego Museum, USA, there are a couple of Kiekhaefer models 045-1 and -3J.

From Appendix A5/6: In the main text we mention the horizontal six-cylinder engine of the year 1958 that was installed on the Del Mar DH-1A “Whirlimite” helicopter.

“The six-cylinder Kiekhaefer engine”

-This engine was actually a modification of the Mercury 800 marine engine, 80 HP lowered to 54/46 HP. The modification was carried out by Kiekhaefer.

“Kiekhaefer Mercury engine ad”

-They also build engines for auxiliary uses, Kiekhaefer has them for every occasion like this small inverted cylinder engine.

“Bilge pump version”

-The engine that attracts us is the one that is normally used in snowmobiles, with an architecture very similar to the aeronautics of Cuyuna, Rotas, Hirth, etc.

"The two-cylinder, air-cooled Kiekhaefer"

-The cooling air for the cylinders is forced by a fan.

-It has a puller starter, as we see in the following illustration.

“Twin-cylinder cutaway”

-It uses the two-stroke cycle for simplifying the system, prioritizing power against a small increase in fuel consumption.

-As we know, with the two-stroke cycle, part of the unburned fuel can be dragged outside through the exhaust ports. As there is one explosion at each revolution for each cylinder it gives a greater additional power, together with a high revolution rate. That is why 60, 70 and more CV is achieved in these small engines.

“Piston deflector drawing”

-To avoid that the fuel is also expelled during the sweep, there are solutions like deflectors on the pistons. Kiekhaefer uses them too.

-See the illustration: at A are the intake ports, B is the deflector, C is the circulation of the sweep -very complete-, D is the exhaust.

From Appendix 6: A two-stroke, 4-cylinder V-engine used in drones.

-The one in the photographs is the V105-2 model located at the New England Air Museum.

“Kiekhaefer V105-2”

-One of the old ranges of Kiekhaefer engines that we received and that we had in mind, is the one of the inverted V series. They were liquid-cooled (freshwater) and were used for marine, air and snowmobiles.

-There were three levels of power: 250 cc with 20 HP, 330 cc with 30 HP and 436 cc with 40 HP.

“Kiekhaefer 2-cylinder inverted V-engine”