Alternators are spun by an engine to generate electricity to run everything from lights to seat heaters, but this puts more load on the engine, limiting power output and reducing fuel economy. Some automakers have tried to address this with 48-volt electrical systems that use a larger battery to provide electrical power, but that adds weight, and you still need to charge it. The mad Russians at Garage 54 have another idea.
These are the same video-producing mechanics that converted a Subaru boxer engine into an inline-four and made a V16 out of chainsaw engines, so they aren’t going to think along conventional lines. They came up with an alternator alternative that’s driven by exhaust gases like a turbocharger instead of a belt, like a conventional alternator. The spinning motion is still used to generate electricity, making this device like a miniature version of the turbines used in power plants. To ensure it generated enough electricity, the Garage 54 crew measured the rpm of a conventional alternator, giving them a spec to design around.
The turbine alternator consists of a round housing and a fan-like wheel made of flat steel blades that gets spun by the engine’s exhaust gases. Those gases enter and exit through ports that had to be precisely located to give the gases a chance to spin the wheel. If they were located directly opposite from each other, for example, the gases wouldn’t have to travel far enough. The clearance between the wheel and housing also had to be as tight as possible to get the most energy out of those exhaust gases, and the entry port and total chamber volume—defined by the housing’s diameter and the number and position of the blades—kept as small as possible to maintain pressure. This required a bit of trial and error.
The finished device is fairly compact, but the installation is not what you’d call OEM-approved. The turbine drives a conventional alternator through a tiny driveshaft, and is plumbed directly to the tailpipe. So instead of sitting under the hood, the entire apparatus hangs off the back bumper on a modified trailer hitch. This is just an experiment, after all.
Exhaust powered turbo-generator for a car – will it work?
But was it a successful experiment? Sort of. The bar was set pretty low; instead of running an entire car’s electrical system, the goal was just to get three light bulbs to stay illuminated. The turbo-alternator was able to do that with about 2,500 rpm from the engine, and made a diabolical noise throughout. The hosts were concerned that too much throttle would cause it to fly apart, but less throttle dimmed the light bulbs.
That’s the problem with turbines. They need to spin at a consistent, generally high, speed to do meaningful work. Anyone who knows even a little about cars is familiar with turbo lag, and while modern turbos and engine management systems have largely eliminated it, doing the same for electricity generation is a bit trickier. That’s why Jaguar had to bail on a turbine range extender for its C-X75 supercar (before bailing on the car itself). A belt is just a more efficient way to harness an engine’s rotation, which is why belt-driven alternators work at much lower engine speeds. Still, the folks at Garage 54 deserve credit for trying.