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Martin Heinrich: Kohler & Polaris Engine Developer

An inside look at Martin's master snow machines
Polaris 600 Pro-X Liberty engine snowmobile Martin Heinrich
Martin Heinrich is perhaps not a name that’s immediately familiar to the general snowmobile public, but his Kohler and Polaris engine designs have been enjoyed by millions of sledders over the last 50 years.

Heinrich’s engines were strong performers on the race tracks and in popular consumer sleds. He also designed some radical 2-strokes, including an 8-cylinder 440 snowmobile racing engine, as well as opposed-firing 4- and 6-cylinder 2-stroke car racing engines that still compete successfully on the SCCA national circuit.
Kohler Free Air engine Rupp snowmobile Martin Heinrich
Give me Liberty or … Kohler? Martin Heinrich contributed to both the Polaris Liberty and many Kohlers (Free Air in Rupp, above).
Kohler H-8 snowmobile engine cylinder piston head Martin Heinrich
A cylinder, piston and head from the Kohler H-8 engine.
How it all started
Martin got his education via the European system, which requires you have solid practical experience as a mechanic, technician or machinist before you are admitted into mechanical engineering studies at a university. Martin served his apprenticeship as an auto mechanic, which no doubt served him well when he started designing engines later in life. Heinrich’s engines were always simple, practical and easy to work on and modify, unlike some of today’s more complicated designs, which sometimes can be a handful to service and modify.  

Since his high school days, Martin had been fascinated with Canada and its wide-open spaces. In March 1967, he left Germany for Canada and a new life, arriving in Winnipeg with his wife and two kids. Here, Martin found work right away and landed in the middle of a new and fast expanding industry called snowmobiling.  

Snowmobiling might have been new to Heinrich, but engines were his expertise. His first employer was Yetman, a powersports distributor in Winnipeg that was also heavily involved in snowmobile racing. Right away, Martin and his engineering partner, Devlin Hunt, began modifying the Moto Sakoshi engines distributed by Kohler of Canada at the time. Heavily ported cylinders, increased compression, Tillotson carbs and some Hunt-designed expansion chambers made these engines the ones to beat.  

Kohler sent 200 engines for Martin and Devlin to modify and distribute to its race teams. Due to the success of their race engines, both were offered jobs at Kohler. Heinrich became chief engineer, and Hunt joined him a year later as development engineer.

Sled-specific engines
Martin’s first big challenge was to design and develop a range of engines for Kohler to set up its own snowmobile engine manufacturing plant, instead of importing European engines. This was a chance to start with fresh new designs built specifically for snowmobiles, rather than using older converted industrial engines, which had been the industry practice up until that time.
Kohler free air engine Rupp chassis snowmobile Martin Heinrich
Fully modified Kohler FA engine in a Rupp chassis.
Mercury 440 Kohler LC engine stock twin pipes muffler snowmobile Martin Heinrich
At vintage races, you’ll find examples like this 440 Kohler LC engine in a Mercury with stock twin pipes and muffler.
Heinrich’s designs became very popular with new snowmobile manufacturers due to their reputation for both power and reliability. Kohler’s new line of engines included the fan-cooled AS 340cc and 440cc engines. Next came three Free Air engines: the FA 340 and 440 twins, and a 440 triple. As the program matured and demand grew, a series of liquid-cooled twin engines (LC 250, 340 and 440) was added to the lineup.

With the successes of Arctic Cat, Rupp, Mercury, and numerous other brands racing with Kohler engines, Heinrich got a chance to go for the “Ultimate 440” race engine design. At this time, max power on the motorcycle road racing circuit was achieved with a greater number of smaller cylinders revving at increasingly higher engine speeds. They raced 125cc twins, 250cc 4-cylinders and even a Moto Guzi 500cc V8 engine. Martin decided the “Ultimate 440” engine should have eight cylinders, but arranging that many cylinders, intakes and exhausts was certainly a challenge that had not yet seen a practical application in the motorcycle world.

Heinrich’s solution was to stack two opposed-firing 4-cylinder engines on top of each other, and gear them to a common center shaft rotating at half speed, thus creating an H-8 engine. This design may seem radical, but H engines were not uncommon in World War II aircraft, which had combinations of up to 24 cylinders. It was also in the BRM Formula 1 car engine, which had 16 cylinders. By using the H-8 design, Heinrich could place four rotary valves on each side and run four pipes out the top and four pipes out the bottom. With a 41.5mm bore and a 40mm stroke, the engine had a displacement of 433cc, and each cylinder was a moped-size 54cc.
Martin Heinrich Kohler H-8 440 snowmobile race engine rare design sketch
Rare sketch of things to come! This is a design sketch of the Kohler H-8 440 race engine.
Martin Heinrich snowmobile engine motor designer engineer
Martin Heinrich
A prototype of the H-8 was built and tested on the dyno, and according to Kohler sources, it produced 135hp at 15,000 RPM. This horsepower output represented a cylinder filling efficiency of 133 BMEP, a realistic output from the cylinder technology at the time. With the main shaft turning at half engine speed, the clutches would turn at 7500 RPM, well within practical limit of belt technology at the time, as 800 triples were producing 150hp. Although the horsepower output was amazing, the whole installation posed a problem that no one was excited about attempting. As a result, no production engines were made, and this very neat design ended up as an impressive trophy.

I have tried to locate this engine, but it was apparently dismantled. However, I was able to source some original cylinders and a design sketch showing the assembled engine. In the summer of 1976, Kohler closed the Canadian operation and moved Heinrich and his family to Plymouth, Wis., where Kohler’s Generator Manufacturing Center is still located today. Devlin Hunt moved on to Arctic Cat, where he ended up as a project engineer and eventually Larry Coltom’s race engineer.  

The move to Wisconsin did not mean Heinrich lost touch with 2-stroke racing and engine design. At the new location, Martin teamed up with Jeff Miller, Kohler’s corporate pilot and an avid sports car racer. With Road America (the famous Elkhart Lake road racing course) in their backyard, and Kohler an enthusiastic sponsor of the popular June Sprints, Heinrich and Miller put their heads together and designed a race car engine using Kohler liquid-cooled snowmobile cylinders and crank parts. The result was an 850cc opposed-firing 4-cylinder engine (actually half of the H-8 design), and later an opposed 6-cylinder engine. Both engines were very successful, earning a large number of National Championships and June Sprints victories.

The two engines have been continually updated over the last 40 years with reed valves and new billet cranks with split bearing technology, and they are still competitive today. Kohler still actively sponsors Jeff’s Wynnfurst Team on the SCCA circuit, and if you want to see one of Heinrich’s racing engines in action, just visit the June Sprints or check out There’s also a video called “Kohler Company video Featuring Wynnfurst Racing” on YouTube. Kohler has actually increased its sponsorship of auto racing, and this past year it sponsored the Indy Car’s return to Road America.
Kohler Free Air engine with head girdle snowmobile Martin Heinrich
Kohler Free Air engine with head girdle.
Kohler engine Mercury snowmobile Martin Heinrich
They came in all kinds, including this Kohler-equipped Mercury.
Liberty engine snowmobile Martin Heinrich
Heinrich designed the Liberty engines, mostly without the use of high-tech computer-aided drafting.
Liberty engine project
Heinrich would still find an opportunity to design a snowmobile engine. During the late 1980s, Polaris was in the process of establishing its own engine manufacturing plant, and after 20 years with Kohler, Heinrich was offered a position with Polaris by Chuck Baxter, the vice president of engineering.  Martin joined a team that was appointed to design and develop the new Polaris Liberty engines. Here, Heinrich’s extensive experience in design, development and manufacturing proved to be a big benefit to the new design. The first Polaris XC 700 twin was immediately a solid success that had other manufacturers puzzled.

I remember being approached by a Yamaha engineer while attending a race in Sweden. He asked if I knew how Polaris could design such a good engine the first time out. Did I know what kind of computer program they had used? My answer was that as far as I knew, Heinrich and his designer had done it the “old-school” way, on a drawing board based on Martin’s extensive experience. I suggested that there probably was more data in Heinrich’s brain than in any 10 computer programs available at the time. The Yamaha engineer walked away shaking his head in disbelief.  

If you’ve ever enjoyed riding a sled with a Kohler engine or a new Polaris Liberty engine, then you have a good idea of what it takes for an engine designer to develop a solid-performing power plant. Why haven’t you heard of Heinrich before?

In our corporate culture, corporate image comes first, and engineers seldom get credit for their work. Instead, a corporate marketer who never designed anything stands up at a press conference and details all the new creations and their many advanced features. This corporate practice is slowly changing. Arctic Cat and Ski-Doo, in particular, have been more complimentary of their designers lately.  

Martin Heinrich passed away on Feb. 2, 2015, at his home in Baudette, Minn., leaving behind a life full of accomplishments after taking a chance on moving to Canada and starting a new life. His legacy of engineering excellence, and his enthusiasm for accelerated development through active racing programs, still lives on in thousands of snowmobiles and vintage racing sleds.
DEVLIN HUNT: Engineering Master
It’s not often you run across a story like the Kohler H-8 Engine. Devlin piqued my interest when he told me about the H-8 project and showed me the cylinders at one of our weekly “Two Wheel Tuesday” meetings at a restaurant in Kenosha, Wis. He also assisted us with background information on his friend and partner, Martin Heinrich, and their early days building Kohler Race Engines.

Always a racer at heart, Devlin’s engineering experience includes employment at Kohler, Rupp, Arctic Cat, Cuyuna, Wallboro and BRP. Although he retired early after heart bypass surgery, he never gave up racing. He was heavily involved in building 2- stroke Yamaha Road Racing Bikes for the AMA and AHRMA vintage series, where his son Ryan and daughter-in-law Evie were very competitive, both winning AMA National #1 plates in the vintage classes.

His last project was designing and building a road racing sidecar from scratch, powered by a 400 Yamaha RD engine. Ryan and Evie raced the sidecar competitively against 4-strokes with twice the displacement.

Devlin was happy that his and Martin’s adventures would be published in AmSnow, which he learned just before he passed away in the hospital due to complications from a massive heart attack on Jan. 24, 2017, surrounded by loved ones. God speed, friend.
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