Isobutanol fuel blends show promise for use in small engines, off-road vehicles

The Outdoor Power Equipment Institute (OPEI) announced the completion of fuels testing on Briggs & Stratton small engines for a side-by-side evaluation of the performance, durability and emissions of ethanol and isobutanol fuel blends. Results show that isobutanol fuel blends provided by Gevo, Inc., do not cause any irregular or unstable engine or performance issues, suggesting that isobutanol could help meet the renewable fuel mandate with minimal-to-no impact on existing equipment and off-road vehicles.

“We are pleased with the results of isobutanol testing,” said Kris Kiser, president and CEO of OPEI. “It shows us that isobutanol could be a biofuel alternative that can be introduced into the existing supply chain without the potential disruption and harm to our outdoor power equipment engines. In the economic interest of our members and the safety interest of consumers, we need to be open to a biofuel that can perform reliably in the millions of products on the market — lawn mowers, chain saws, motorcycles, snowmobiles, ATVs and UTVs, boats and older cars.”

Briggs & Stratton (B&S) ran a test program with isobutanol provided by Gevo, a renewable chemicals and advanced biofuels company. Isobutanol, which can be produced out of corn starch, cellulosic materials, agricultural residues and other ethanol feedstocks, is an alcohol that acts like a hydrocarbon. Therefore, this four-carbon molecule could function as a “drop-in” product to allow customers to replace petroleum-derived raw materials with isobutanol-derived raw materials without modification to their equipment or production processes.

“Briggs & Stratton is encouraged by the results of the isobutanol testing on our engines,” said Todd Teske, chairman, president & CEO of Briggs & Stratton Corporation. “We are very interested in alternative fuels that do not cause damage to the substantial number of engines in use today while lessening the country’s dependency on foreign oil.”  

“These positive results show that isobutanol is an excellent gasoline additive,” said Pat Gruber, CEO of Gevo, Inc. “If isobutanol blends run well in small engines, they should run well in all engines without the need for flex-fuel retrofits, blender pumps or new infrastructure as our own, previous testing, has shown. Renewable isobutanol should therefore make it easier for the nation to gain energy independence and meet mandated biofuel targets.”

After testing three different B&S engine models on gasoline containing 12.5-percent isobutanol, the following results were recorded:

No engine or performance issues were found while running on isobutanol.
Horsepower and torque levels remained the same while running on isobutanol.
Equivalent or better performance than E10 at temperatures ranging from 40 to 120 degrees F. 
No significant change in emissions (HC+NOx) levels.
Isobutanol does not absorb water like ethanol. This will lead to fewer problems in the seasonal use conditions and long storage periods that are common with small-engine applications.

For more information about OPEI, visit www.OPEI.org.