New Propane-Powered Bobtail

Propane marketers have heard the news over the past year that the industry would once again have a propane-powered bobtail. Marketers will finally be able to run their bobtails on the fuel they sell.
Up until now, two companies had announced they are working on bringing the vehicles to market. Freightliner Custom Chassis Corp. in March 2012 unveiled the Freightliner S2G, an 8.0-L propane-powered truck, at 33,000 GVWR with 500 lb-ft of torque at 3100 rpm. Roush CleanTech has also introduced its liquid propane autogas system for the 30,000 GVWR Ford F-650, with 457 lb-ft of torque at 4750 rpm, meant for those looking for a smaller, 2800-gal. bobtail and for other applications.
Now there are three.
This month at the National Propane Gas Association (NPGA) Southeastern Convention in Atlanta, a third propane-powered truck is entering the marketplace. Tri State Tank (TST; Kansas City, Mo.), Alkane Truck Co. (Myrtle Beach, S.C.), Truck Centers Inc. (Troy, Ill.), and Fontaine Modification (Charlotte, N.C.) are unveiling a new propane bobtail using the propane autogas Liberator engine. What makes this engine different is its ability to reach very high torque levels at very low rpm. The Liberator engine features 630 lb-ft of torque at 1900 rpm. According to the companies, the high torque of the Liberator makes its performance comparable to diesel-powered trucks, and it will offer significant fuel cost savings. The low rpm will also increase a vehicle’s longevity.
The high torque and low rpm address a problem with gaseous fuel engines, said Steve Rayborn, global director of sales for Alkane. “They haven’t produced a high enough torque level at efficient rpm where the fleet operator felt confident of the capabilities of that engine.”
Like the Freightliner S2G propane bobtail, the truck with the Liberator engine is based on the Freightliner M2-106 medium-duty chassis.
Truck Centers sales executive Ron Donze noted that the M2-106 is an ideal application for pickup and delivery industries such as propane because the vehicle allows great driver visibility and maneuverability. ”That’s what sells the product. You can see out of it so well and it turns so sharp,” Donze noted.
Jody Stirewalt, president of Liberator Engine Co. LLC (Asheville, N.C.), describes the Liberator engine as a “torque monster.” Stirewalt is also president of Certification Services International LLC (CSI), which specializes in design, development, and certification of alternative fuel systems, vehicles, and engines for CNG, LNG, and other alternative fuels in addition to propane.
The new bobtail using the Liberator engine removes the doubt that marketers felt about using a propane-powered bobtail, Stirewalt commented. The propane industry has always made excuses about why it hasn’t used its own product to fuel its delivery vehicles, he added.
“They never had as much power, never got as much fuel mileage, or there was always something that didn’t add up to the gas or diesel counterparts,” Stirewalt noted. “It just never did anything as well, especially in the heavy-duty market. It never made the power, wouldn’t start when it was cold, it had all these issues. When we designed this new engine, we said ‘We know what all these things are, let’s fix all of them.’ And that’s what we did. So we have an engine that will run, it will start, and will make the same kind of power that an equivalent diesel will make. It will make it at the same rpm, and it will have the longevity of a diesel engine. So we don’t have to make excuses anymore.”
The concept for the project began only about a year ago, when Stuart Weidie and Jessie Johnson of Blossman Gas and industry coalition Alliance AutoGas (Ocean Springs, Miss.) met with Stirewalt and CSI vice president Par Neiburger and saw the company’s CNG version of the Liberator engine. Weidie and Johnson were impressed with CSI’s work and encouraged Stirewalt to seek Propane Education & Research Council (PERC) funding to bring the propane version to market.
Weidie and Johnson encouraged PERC director of autogas business development Michael Taylor to look at Stirewalt’s work, and this past July PERC approved $700,000 in funding for the project. “We just wanted to encourage them to continue their efforts because they were working on a substitute for an engine platform that’s one of the most popular in the United States for on-road and off-road applications, the Cummins 5.9L,” Weidie commented.
Taylor said PERC benefited from CSI’s willingness to develop a propane autogas engine simultaneously with its CNG/LNG version. With simultaneous design, development, testing and certification, PERC’s project costs were reduced, he noted.
From PERC’s perspective, Taylor added, the Liberator 6.0-L will not compete against Freightliner’s S2G 8.0-L. “The projects will complement each other and provide fleet directors and managers with a choice regarding engine type and options needed for their applications and preferences.”
Those involved with the Liberator product say, however, that increased torque at a lower rpm gives the Liberator product an advantage. Running high torque at a high rpm severely harms an engine’s durability, Stirewalt explained.
“It’s just the wear factor,” he added. “If I can run half the speed as you, I can run twice as long. That’s why a diesel engine will go 350,000 miles and a gasoline engine might go 125,000 or 130,000. With the same amount of torque but running at a much lower rpm, you end up getting the longevity.”
Stirewalt also noted that rather than place a turbocharger in the exhaust system to gain additional horsepower, his company is using a supercharger that offers the benefit of programmability.
“You can stand and watch our engine and say, ‘I want to see 17 pounds of boost at 1100 rpm,’ and with computer-controlled digital accuracy, we can deliver that,” Stirewalt stated.
Various steps are involved in bringing the new bobtail to fruition. Truck Centers Inc., a Freightliner dealer group that provides truck sales, parts, and services to the medium- and heavy-truck industry, furnishes and orders the glider kit (a new chassis less a major component such as the engine or transmission) for the model. Donze of Truck Centers explained that his company sends the glider kit to Fontaine Modification, which installs the engine, accessories, and motor fuel tank.
Alkane Truck Co. coordinates the process of producing a functional chassis. The company purchases the glider kit from Truck Centers, then Alkane orchestrates installation of the Liberator engine by Fontaine Modification. Fontaine installs the engine and motor fuel tank and integrates it all with the Freightliner chassis. Once Fontaine’s work is done, the truck goes back into the normal shipping channels for delivery to a body installer, such as TST.
“Some of the intrinsic qualities of this truck and engine, besides excellent fuel efficiency, is you can place a glass of water filled to the brim on this engine and it will not spill, unlike most other diesels that are noisy, they vibrate, and emit terribly odoriferous [fumes],” said Rayborn of Alkane. “Diesel exhaust smells terrible. We are very clean burning with low emissions. A very green product.”
Tri State Tank will be one of the primary sales channels to get the vehicle upfitted with a cargo tank and then out to the propane marketers. TST and Alkane will place the unit into real-world service for testing and evaluation, said Jason Soulon, Tri State sales manager. “We’re going to have this truck in stock, and we’re going to have tanks already mounted on it and ready to deliver propane just like we do today with our diesel-powered trucks,” he noted. “We expect this truck to comfortably haul a 3200-gal. tank, perhaps more, and we hope to be selling trucks in fall of 2013.”
-—Daryl Lubinsky