University of Maine’s Flex Fuel Capable Four-Stroke
Snowmobile
Joseph Stilwell, Kazuki Iwakura, Eric Whitman, Kevin Bowler
University of Maine
Abstract
For the 2010 Clean Snowmobile
Challenge (CSC), the University of
Maine is submitting a secondgeneration four-stroke snowmobile
capable of running on flex-fuel.
Through the use of an engine control
unit (ECU), Microsquirt, the
snowmobile can successfully be tuned
to improve fuel consumption,
decrease emissions, and maintain the
stock engine configuration. Engine
noise and vibration is reduced using
sound absorbing materials around the
inside of the cowling as well as under
the seat to prevent noise from the
exhaust system. The Umaine Phazer
meets emissions standards through
the use of a new catalytic converter
and is fuel-efficient.
Snowmobiles provide outdoor
enthusiast the opportunity to
experience the thrill of trail riding
during the winter months when snow
is abundant. Although snowmobiles
provide entertainment, they also
contribute to environmental pollution
through excessive emissions and they
can be extremely noisy in residential
areas. The Society of Automotive
Engineers (SAE) developed the Clean
Snowmobile Challenge in 2000 for the
purpose of re-engineering
snowmobiles to produce fewer
emissions, operate quieter, and
consume less fuel through a
combination of ethanol and gasoline
(flex-fuel). At the same time the
Design Goals – The overall goals for
the 2010 clean snowmobile team is to
reduce exhaust emissions, mainly HC,
CO, and NOx, and reduce noise and
vibration from the snowmobile.
Through the use of a five-mode gas
analyzer, emission testing has taken
competition snowmobiles need to
perform at the same level as the
original equipment manufacturer
(OEM) and are expected to
significantly reduce hydrocarbons,
carbon monoxide, nitrous oxide, and
excessive noise.
Introduction
This paper discusses how the 2010
University of Maine team has modified
the 2007 Yamaha Phazer Snowmobile
for the 2010 CSC in order to reduce
emissions and sound while
maintaining the OEM performance
and riding characteristics. This paper
also discusses what the team kept
from the previous years team in a
summary form.
place to compare the emissions
produced from the stock exhaust
system and the emissions produced
from the custom exhaust system with
the three-phase catalytic converter. In
order to reduce noise and vibration,
sound deadening materials have been
placed around the cowling, inside the
engine walls, and underneath the seat
to help reduce the sound and
vibration from the engine output.
Umaine Design
nitrous oxide (NOx). The catalytic
converter features a 2.25” center
inlet/outlet pipe, 9 x 5.125” round
body, and is 13” in overall length.
Figure 1 shows the catalytic converter
mounted onto the customized exhaust
system.
The Baseline Snowmobile – The stock
specifications for the four-stroke 2007
Yamaha Phazer snowmobile are listed
below in Table 1.
Engine Type
Four-Stroke
Cooling Method
Liquid Cooling
Cylinders
2
Engine
499 cc
Displacement
Compression Ratio
12.4:1
Maximum Power
80 HP
Dry Weight of Sled
454 lbs
Size of Fuel Tank
11.4 gallons
Fuel Type
E20-E29
Table 1 – Stock specifications of the
2007 Yamaha Phazer Snowmobile
EMISSIONS CONTROL- There is two
methods to improving the emissions
produced by the snowmobile. The first
method is a mechanical method and
the second method deals with the
electrical wiring of the Microsquirt
engine controller.
Mechanical Method: The 2010
University of Maine clean snowmobile
team chose to incorporate a 3-way
catalytic converter into a customized
exhaust system. The catalytic
converter used in the customized
exhaust system is designed for
automotive applications. The 3-way
catalytic converter is a Magnaflow
performance catalytic converter
capable of oxidizing hydrocarbons
(HC), carbon monoxide (CO), and
Figure 1 – Custom exhaust system with
new 3-phase catalytic converter
Figure two shows the Yamaha Phazer
with the stock exhaust system. The
stock exhaust system was used to
compare emission production and
sound production from the
snowmobile.
Figure 3 – Custom muffler with three
chambers and expander
Figure 2 – Yamaha Phazer with stock
exhaust system
Figure three shows the custom
muffler being constructed to
accommodate the new exhaust system
with the catalytic converter included.
The muffler consists of three
chambers with an expander. The
exhaust will enter the muffler through
a 2.5” opening in the front, move
through the center chambers while
expanding, and then circulate back
through the side chambers and exit
through the bottom of the muffler and
out into the atmosphere. With the
addition of the new muffler, sound
and vibration from the sled will be
reduced.
Electrical Method: The 2009 clean
snowmobile team chose to implement
the use of an engine controller,
Microsquirt, for the purpose of tuning
the engine of the snowmobile to
produce fewer emissions. Microsquirt
allows the user to optimize ignition
and fuel delivery parameters to
balance the ratio of ethanol and
gasoline for better performance as
well as optimize fuel economy and
emissions. The Microsquirt unit is a
Bowling & Grippo unit chosen for easy
compatibility with the stock Yamaha
Phazer sensors and for easy
programmability and tuning. The
2009 clean snowmobile team varied
the spark ignition, air-fuel ratio, and
volumetric efficiency to determine the
best combination for optimum fuel
efficiency and emission production.
The 2009 team used Microsquirt to
control the fuel delivery with a
measured air pressure to allow the
most useful mixture of air and fuel to
be delivered to the engine of the
snowmobile. The variability of the
Microsquirt unit can determine the
right ratio of air and fuel to be
delivered. If the mixture is too lean
then the sled will lose power and
backfire. If the mixture is too rich the
exhaust produces a heavy black smoke
and the throttle response is very
sluggish. Microsquirt allows these
parameters to be adjusted in order to
find the right mixture for optimal
performance. The 2009 team
implemented this unit into the engine
controller and adjusted the
parameters to produce the most
power, fewer emissions, and better
response from the snowmobile.
decoupler [1]. The Vcomp noise
barrier is being used inside the
cowling as well as around the steering
column and dashboard of the
snowmobile where vibration is an
issue. Shown below are
representations of the B-Quiet
Ultimate and the B-Quiet Vcomp
materials used.
Shown below are the emissions
produced from the stock Yamaha
Phazer snowmobile.
Figure 3 – B-Quiet Ultimate used under
the riders seat. Rated for high
temperatures
SOUND & VIBRATION: In order to
reduce the sound and vibration and
the Yamaha Phazer, the 2010 clean
snowmobile used sound deadening
materials that have been placed in and
around known areas where sound and
vibration are prevalent. Two materials
have been used to reduce sound and
vibration of the snowmobile. The first
material used was B-Quiet Ultimate,
which is a 1.6mm thick viscoelastic
deadener rated for high temperature
which is being used underneath the
rider seat where temperature from
the exhaust is highest. The second
material used was B-Quiet Vcomp
which is a composite noise barrier
consisting of a dense 1/8” vinyl based
polymer barrier with a ¼” thick foam
Figure 4 – B-Quiet Vcomp composite
noise barrier used under the cowling
and around the steering column and
dashboard
References
[1] B-Quiet