A bolt-on hybrid system that could double fuel mileage in a full-size truck drew some of the largest and most curious crowds around a single vehicle at this past SEMA Show.

Showcased in a ’57 Pontiac Chieftan, the 6.0-liter LS engine was assisted by an E-Charger system developed by Johnathan Goodwin, a well-known figure in the green automotive movement who has handled conversion projects for entertainment stars like Neil Young and Arnold Schwarzenegger. Prominently protruding above the Vortec manifold was a 50 kW AC motor turned by a supercharger pulley and Gilmer belt drive. Walk around to where the truck lid was open and there was a battery charger and 35 lithium-ion battery cells.

“I had people tell me that I build cars for famous people, but what can you do for me,” says Goodwin.

The 50 kW motor will add up to 150 lb-ft of torque to the main engine.

The system Goodwin developed has just three components: motor, controller and battery pack, along with the necessary wiring. Immediate goals include working with suppliers to get costs down and design bolt-on kits for popular applications that traditionally struggle with fuel economy — and that vehicle segment is usually driven by full-size trucks and SUVs. Not only do they have the worst gas mileage — aside from a few supercars — but they have the real estate under the hood to support the motor and the GVWR to handle the extra 220 pounds of batteries.

The motor is connected to the crankshaft via 1:1 belt drive and provides up to 150 lb-ft additional torque. It’s also regen capable, so during braking or off-throttle events the motor turns into a generator and puts energy into the batteries where it can be used later during acceleration.

“Which is your biggest cost factor when driving a vehicle,” adds Goodwin.

There are 35 3.32-volt lithium-ion batteries behind the cover in the trunk. Note the 3 kW battery charger that can be plugged into a household outlet or a standard EV charging station.

The E-Charger system is also designed as a plug-in hybrid. There’s an electrical port mounted in in the right rear quarter panel that allows charging from a household outlet or standard EV charging station.

“It costs me 75 cents a gallon equivalent to charge at home,” says Goodwin. “That’s a two or three hundred percent savings on my fuel source, it’s way cleaner.”

This 6.0-liter LS engine came out of a H2 Hummer. Full-size trucks stand to gain the most benefit from such a bolt-on hybrid system.

The controller features a proprietary power map that looks at engine functions such as manifold pressure, inlet airflow and throttle position. There are two driving modes: city and highway. The city will apportion the battery power more aggressively than the highway to provide the best mileage for the condition. Goodwin is also working on a phone app that will let the user dial in the projected driving distance to maximize efficiency for a specific distance.

The engine and system shown here originally came out of a .05 H2 Hummer that never drew much attention while on display at previous SEMA shows. Officials suggested building a different type of vehicle.

“So I snatched that motor out and put it in an old car to see if I could get some love,” says Goodwin.

The pulley system runs at a 1:1 ratio. The motor is also the starter for the engine, and the system is start-stop capable.

While in the Hummer the LS engine recorded an average of 12 mpg. With the E-Charger system the average fuel economy jumped to 30 mpg for a 30-mile range.

“With the system off, it’s just a big old heavy Hummer,” quips Goodwin. “With the system on it feels like it has nitrous.”

Those mileage numbers are not certified by any means; however, the car is currently at the emissions facility in the SEMA Garage undergoing tests.

Goodwin won’t announce pricing as discussions continue with suppliers, but “under $5,000” was stressed.