Fueled For Success – This Streamliner Uses CNG To Assault The Salt

lessman

Roger Lessman is a 30-year veteran of competition on the Bonneville Salt Flats, and is attempting to make his AA/BGS Streamliner the  quickest in the world using compressed natural gas as a fuel.

What does it take to make 1,500hp? A lot of cubic inches? Maybe some boost? It certainly takes a lot of fuel. It sounds like a fairly simple recipe, but for Roger Lessman, it might not be that simple.

Roger Lessman is the owner and pilot of an AA/BGS streamliner, which he competes with on the salt at Bonneville. This unique 29-foot long top speed machine is a single engine, all-wheel-drive streamliner, but it’s not its length or drive system that makes it so unique. The car is fueled by compressed natural gas.

Lessman set a record with his previous streamliner in the E/FS class in 1989 at 292.719 mph. His goal is to set another record with his current streamliner, but it will not be an easy task. The current AA/BGS speed record is 348.342 mph.

The engine configuration is fairly simple. It starts with 572 cubic inches of big block Ford power, force-fed by a pair of Bullseye turbochargers. Where it becomes a little more exotic is the fuel. Compressed natural gas (CNG) has started making its way into the racing world as a viable fuel over the past few years.

The Roush drag racing teams have found great success with the fuel, and Lessman is well on his way to being the fuel’s next overachiever. This is largely in part to his tuner, Shane Tecklenburg (Tuned By Shane T). We caught up with Tecklenburg to discuss some of the differences and challenges associated with making big power capable of running this insane speed using compressed natural gas as fuel.

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“Fuel delivery is the biggest challenge when it comes to CNG,” explains Tecklenburg. “Most of the fuel system components that are available are designed for industrial applications. Making the system work for high horsepower applications means a lot of custom made parts. The gas in the tank is stored at very high pressure. Because of the pressure, regulators become very critical.”

The tank sees about 3,000 pounds per square inch of pressure when it’s full, but rail pressure is only 175-180 psi. It’s easy to see why the regulator becomes such a crucial part of the equation.

Although driveline issues have prematurely ended multiple attempts for the team, the numbers they have achieved are very promising for s successful future.

Although driveline issues have prematurely ended multiple attempts for the team, the numbers they have achieved are very promising for a successful future.

Tecklenburg tells us that when he started with the team in 2010, the fuel system would only support about 450 horsepower. This was due to the lack of adequate available parts. Coupled with turbos that weren’t up to the task, the team redesigned the air and fuel systems, which would pay huge dividends in the power department.

The upgraded fuel system and larger Bullseye turbocharger now make the 572 cubic inch powerplant capable of cranking out in the neighborhood of 1,500 horsepower, but so far they have only pushed it to approximately 750 as they sort out the combination. Tecklenburg tunes the streamliner using a MoTeC M800 ECU and MoTeC CDI-8 Ignition box. He explained some of his calibration strategies with CNG compared to gasoline.

“There really isn’t much difference when tuning for CNG,” he explains. “The concepts are the same, the numbers are just different. The stoichiometric number for CNG is 17.24:1, so it’s different than gasoline from that standpoint. The biggest difference is that because you are dealing with a gas instead of a liquid fuel, all the problems with transporting the fuel to the cylinder are removed. You no longer need additional enrichment to make up for a disruption in fuel puddling on the port walls during transients (rapid changes in manifold pressure).”

The tuning process for startup is a bit different from a gasoline-fueled engine.

inshop“You similarly don’t require cold starting enrichment, again because the fuel being a gas does not condense on the cold portions of the inlet system. The octane level of CNG is about 130 and it has a very high burn rate, so detonation isn’t as big of an issue. Its heat energy isn’t as high as gasoline, so it will make less power with the same compression. But if you optimize the engine (compression) for CNG, it will more power and it’s much more efficient. When optimized in this manner, CNG offers increased fuel economy at part throttle over traditional liquid fuels,” he says.

Tecklenburg explained that CNG also burns very clean when compared to gasoline or methanol. When you look at the plugs there are no carbon deposits on them, so it makes it difficult to read them to assist with tuning changes. There are also no carbon deposits left in the exhaust.

When Lessman last made the trip to Bonneville in 2010, the streamliner was sidelined with clutch issues. After fixing the issues and making the air and fuel changes, the team finally made the trip back in 2014, just a few weeks ago.

Unfortunately, another driveline issue ended the team’s World Of Speed event early, yet again. In the process, Lessman hit 316 mph going into the fourth mile, but poor salt conditions caused him to lift and abort the rest of the run – showing that the potential is there for the machine to achieve Lessman’s goal.

With the current engine configuration and Tecklenburg behind the laptop, Lessman Racing is well on its way to holding yet another record at the famed Bonneville salt.

About the author

Pete Epple

Pete Epple has been an automotive enthusiast for the better part of 30 years, and a racer for nearly as long. He's been writing about cars for nearly 10 years.
Read My Articles

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