There’s been a lot development going on with diesel engines lately, particularly in Europe. Volkswagen and Mercedes, among others, have diesel-powered cars that get fabulous fuel mileage and Daimler AG introduced a three-cylinder, diesel-powered Smart Car in March of 2009 that, reportedly, gets 85.6 mpg in combined city/highway driving. The gasoline powered Smart Car available in the United States gets 33 mpg (city)/41 mpg (highway).
During the oil embargo of the 1970s, diesel cars were looked at as a partial solution to the fuel supply problem. General Motors converted several of its existing gasoline V-8 engines into diesels, but they were unreliable, short-lived, had enormous drivability problems and were nearly unstartable in cold climates.
In short, the U.S. manufacturers’ crude attempts to create diesel-powered cars were a dismal failure and left a crude taste in Americans’ mouths for diesel cars. But what about diesel engines in snowmobiles? I know of two attempts to use small, three-cylinder engines in the over-the-snow vehicles.
The Latest, Cleanest Diesel Technology
New injection systems, the use of electronic engine management systems, new combustion chamber designs and exhaust-after treatment systems and materials are really changing how we will be viewing diesel engines — in many applications.
One reason diesel engines are regaining favor around the world is that they are more efficient than gasoline engines and they produce less carbon dioxide. They do, however, pollute more by producing more particulate matter and higher nitrogen oxide levels. Most motor heads realize that carbon dioxide is not a pollutant, but particulate matter and nitrogen oxide certainly are.
To control the nitrogen oxide emissions from new diesel engine designs, a technology called selective catalyst reduction is used. A liquid known as AdBlue is injected into the exhaust system to turn nitrogen oxide emissions into harmless nitrogen and water. AdBlue is a mixture of roughly one-third pure urea and two-thirds demineralized water. AdBlue costs about $34 per gallon, but at the rate it is injected into current diesel automobile engines it translates to just $7 for each 620 miles traveled.
A number of filters are being used to trap particulate matter and actively burn it on the new diesels. An interesting filter being tested uses centrifugal force to remove the matter from the exhaust gasses. Exhaust flow is used to rotate a turbine-bladed muffler through which the exhaust flows. Filters trap and burn the particulate matter at the outer diameter of the device. This design adds real meaning to the old joke about having to change your muffler bearings.
Will It Work In A Snowmobile?
Gerard Karpik, proprietor of TeamFAST in Eveleth, Minnesota, built the first modern snowmobile I heard of being powered by a diesel engine. The machine was tested in 2000 in an effort to supply the military with a snowmobile that could operate on kerosene or jet fuel available at virtually all military bases.
Karpik used a Yamaha hydrostatic transmission rather than try to apply a centrifugally governed drive and driven pulley system found on all snowmobiles today. It was a much easier way of dealing with the low-rpm, high-torque output of the diesel. The engine produced 45 hp and would propel the sled to a top speed of 60 mph. The machine had low-temperature starting problems, was heavy and lacked the performance the military needed, so the project was scrapped.
In the spring of 2007 I went to Houghton, Michigan, to take a look at the Society of Automotive Engineers (SAE) Clean Snowmobile Challenge (CSC). I’d been following the efforts of the CSC since it started in March 2000 and was thrilled to finally be able to attend one of the events.
Would you like to take a guess at what internal combustion powered snowmobile at the 2007 CSC had the cleanest exhaust emissions? Go ahead, I’ll wait…. Well, it came from the State University of New York (SUNY) at Buffalo. The team installed a Briggs and Stratton, three cylinder diesel engine — built by Daihatsu of Japan — in a Polaris Pro X chassis.
The engine was a turbocharged, four-stroke, direct injected design displacing 953cc. The little diesel produced 34 hp with 58 pound-feet of torque. To cool the compressed air from the turbo charger, the SUNY-Buffalo team installed an air-to-water intercooler. Additional heat exchangers were added to the chassis tunnel to cool the water from the intercooler.
The exhaust was treated through a de-oxidizing catalyst (DOC) hybrid exhaust system that was equipped with a filter that traps the particulate matter in a fleece material, where it is actively burned at 392 degrees F.
The SUNY team’s diesel snowmobile weighed 732 pounds, the second heaviest in the internal combustion category. While the team had a number of problems with its sled and it was disappointingly slow, it shocked the judges when it plucked the lowest exhaust emissions prize.
In the ensuing two years, the team has refined its diesel-powered snowmobile and, in fact, captured the “Most Improved” category in the 2009 competition. For the 2009 competition, the SUNY-Buffalo team installed the Daihatsu diesel in a 2005 Polaris IQ chassis, thereby losing some weight and gaining a better cooling system.
One problem with previous versions of the sled was getting the drive and driven pulley calibrations figured out. It’s tricky to tune a centrifugally governed transmission when the engine’s peak power is 40 hp that comes in at 3800 rpm and peak torque is 68 pound-feet at 2600 rpm. The team installed a Comet four-weight drive pulley and got enough weight on it to get engagement down to 2600 rpm. A TEAM Industries roller driven pulley did the job on the other end of the belt.
During its testing, the team measured fuel mileage to be 35 mpg while the machine that won the mileage category at the 2009 CSC got 13 mpg. To register their mileage for the event the team had to complete a 65-mile endurance course. An electrical switch failed and the team was unable to finish the event. Had the machine finished the lap, the team would have won the mileage category.
For 2010, the SUNY-Buffalo team would like to get its hands on a turbo diesel from a Daimler Smart Car. The engine weighs less than the Daihatsu and makes twice the horsepower at 6000 rpm. Unfortunately, it’s very expensive.
I hope the SUNY CSC team gets that engine for their next entry. The team has made significant progress and it’s starting to make me think, “Yes, there is hope for a diesel-powered snowmobile!”