Turf Magazine - October, 2008
New engine for commercial mowers
Gasoline is such a part of
our lives that it’s sometimes difficult to imagine what we’d do
without it. But, increasingly, our minds are being expanded.
“Alternative fuels” has become a commonplace phrase in news
reports, political discussions and even tailgate talks on the job. Whether
the concerns are related to high cost, shrinking supply or the environment,
individuals, businesses and governments are looking for new fuel solutions
that can substitute for gasoline.
It’s not just automobiles involved in the
alternative fuels arena, Briggs & Stratton recently developed a
propane-powered engine for use in commercial mower applications. The
primary goal was to produce a low-emissions engine (the World LP Gas
Association states that “compared to gasoline, propane yields 12
percent less carbon dioxide, 20 percent less nitrous oxide, and as much as
60 percent less carbon monoxide) that would allow commercial lawn care
companies to operate freely in the growing number of cities that have
instituted “Ozone Action Days,” banning the use of commercial
mowers after 1 p.m. At the same time, the engine would have to live up to
the expectations of commercial end users in terms or power, performance and
While there have been a variety of efforts in the lawn
and landscape industry in the past to convert existing engines to use
propane fuel, the Briggs & Stratton effort represents an engine built
by the factory specifically for propane. It started with a proven base
package: the Briggs & Stratton Vanguard Big Block V-Twin engine. With
more than 50,000 Big Block engines already in use, the durability and
reliability of the engine were known qualities. The next step was to
undertake the necessary engineering changes and testing to produce an
engine tailored for use with propane.
“The Vanguard Big Block was the perfect engine
to work with,” says Mike Braun, product manager with Briggs &
Stratton, who worked on the project. “There were many improvements
made when we designed that engine; it was built nice and robust, so the
propane was a good fit.” He adds, however, that during the propane
engine’s development, there were some basic changes that were made:
“We ‘stress-relieved’ all of the castings to ensure good,
precision machining. We used iron exhaust valve faces to provide endurance,
and a specially designed carburetor designed for use with propane. The
ports are different, the jetting is different.”
The development of the engine was a joint project
between Briggs & Stratton and Ferris, and the propane engine is
currently available on the Ferris IS 3100ZP zero-turn mower. Briggs &
Stratton’s Engine Application Center in Milwaukee, Wis., was tapped
to help apply the knowledge developed in building the generator engines and
make it work with a commercial zero-turn mower. Ferris took a lead role in
the development and testing, which took place in Florida. “We all sat
at the table and used our resources to audit the overall design and test
the ideas to be sure it would work,” says Braun. “Every time we
got test results back, we learned more and more about integrating the
engine and the mower.”
|Photo courtesy of Ferris.
|The Ferris IS 3100ZP zero-turn mower is powered by a Briggs & Stratton Vanguard Big Block propane engine.
Briggs & Stratton offers standby generators for
homes that are powered by natural gas, so the company is not new to the
concept. Braun says one of the challenges was to take that propane engine
technology and adapt it to the special circumstances encountered in
commercial mowing, namely the bouncing, turning, and ups and downs.
“We had to make sure we had the proper withdrawal system from the
tanks,” he explains. “We used special ‘vapor
withdrawal’ [as opposed to ‘liquid withdrawal’] fuel
tanks to ensure consistent, hassle-free operation. We set the
‘pick-ups’ in the tanks so that they would always be
withdrawing vapor; there will never need to be liquid going through the
regulator into the carburetor.”
Visually looking at the propane engine itself, users
will notice a few differences. “One nice thing is that there is no
choke on the system,” says Braun. “It might seem strange on a
commercial unit to not see a choke, but the propane system doesn’t
There are additional ways in which the propane engine
is simpler to operate and maintain. “With gasoline engines, we try
our best to adjust carburetors to work well with different gasoline
volatility levels, which change over time and with different seasons and in
different areas of the country,” says Braun. “There are summer
blends, winter blends, different ethanol blends and so on. With propane,
you don’t need to worry about that. The fuel is very
consistent.” Briggs & Stratton was better able to dial in the
calibration of the carburetor for optimal performance.
In addition to producing fewer emissions while
running, the propane engine is more environmentally friendly from a fueling
standpoint. “There is a lot of evaporative emissions that happen with
gasoline, and people often spill it,” says Braun. “With the
engine, the way the tanks are connected and
disconnected is much friendlier in that regard. There is very little chance
to create emissions from spilling.”
Dan Roche, marketing manager for the Briggs &
Stratton Commercial Engine Division, says the company is working to promote
the benefits of the propane engine to its customers; and for many,
it’s a new concept. “I think for most of our commercial
customers, the biggest concern has to do with power. They want to be sure
the engine is powerful enough to cut thick, wet grass,” says Roche.
In large measure, any such questions are answered by
the base Vanguard Big Block engine. “The large displacement brings
the torque that gets the job done. That’s what keeps the deck
spinning, keeps the wheel motors moving, and keeps lawn care companies
productive,” Roche says. Briggs & Stratton rates the engine in
terms of displacement (the volume is 895cc) rather than horsepower.
To assure commercial users of the performance and
reliability of propane-power engines, Briggs & Stratton points to the
longtime use of this fuel in forklift applications. “Forklifts are
heavy-duty pieces of equipment, just like commercial mowers. They’re
relied upon by businesses, just like commercial mowers. And, they have a
long track record of being very safe and efficient,” says Roche.
The other area where perspective users have questions
has to do with “fuel handling,” says Roche. “Gasoline is
a volatile fuel, but we all handle it so frequently that we’re
comfortable with it. People are familiar with it,” says Roche. To
help promote greater understanding of propane as a fuel source for its
engines, Briggs & Stratton is working with the Propane Education &
Research Council to help develop educational and training materials.
“We’re working very closely with them. We know this is a new
fuel for people to work with, and we want to make sure we’re
providing all of the necessary safety and handling instructions in all of
our manuals and literature.”
Roche says that even those just hearing about
propane-powered mowers have some understanding of the benefits of propane.
“They view it as a ‘clean’ fuel. To them, that means
there are no ‘Ozone Action Days’ to slow down their business.
And, propane is known as a fuel that ‘doesn’t go
bad.’” He thinks that these attributes will help the technology
spread in the industry.
At press time, Briggs & Stratton was offering the
propane engine to any commercial lawn mower manufacturer, but those mower
companies interested in using the engine are responsible for arranging and
equipping their mowers with the necessary fuel delivery system (a product
designed to deliver the propane from the propane cylinders, through a
regulator and to the engine). The Ferris mower currently on the market uses
a system produced by Onyx Environmental Solutions.
Patrick White is a freelance writer and editor who is
always on the lookout for interesting and unusual stories.