Quote:
Originally Posted by stugray
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That's an electric turbine without the compressor side. At full throttle on a naturally aspirated engine there is ~7% or so (depending on the engine) extra power to be picked up by placing a turbine in the exhaust, but at less than full load it will be pretty much dead-weight.
That said, essentially what this turbine picks up is the sound energy coming from the blowdown at each exhaust. It would provide a muffling effect to the exhaust so if it allows you to shed resonators and mufflers while providing a small bit of power, that's a win-win. Unfortunately, that doesn't seem like it could ever be very cost effective lol.
Most of the energy going out the tailpipe is in the form of waste heat. You have to use a heat exchanger of some sort to capture this waste heat because if you try to convert it to pressure to drive a turbine, that pressure will be pushing back on the engine. Notice how that TIGERS thing produces 2kW maximum. BMW's "Turbosteamer" concept produces
10kW peak and well over 2kW in regular driving. Extremely inefficient low temperature thermoelectric generators hooked up to the exhaust will be giving you a constant 300W while barely using much of the heat from the exhaust at all. Experimental high efficiency, high temperature TEGs could provide way more power than a modern car's electrical systems could ever use for free from exhaust gas.