| serialk11r |
10-09-2020 11:43 AM |
Quote:
Originally Posted by Dadhawk
(Post 3374402)
I would love to have a car that was pure generator driven, no massive battery pack. OK, it's not "green" but it would have the performance of an electric without the compromises.
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That's called a series hybrid. Doesn't really work if you want performance because the generator has less power than a normal engine because it's supposed to represent the average load. You would need an intermittent power source (small battery or capacitor pack), and the car would only be barely faster on the track than something powered by the same engine.
I guess on the street you only need short bursts of acceleration which is maybe what you were getting at. In that case yes, you could end up with a lightweight car using a tiny generator, though it would struggle to climb a mountain since the battery would be quickly depleted. At the end of the day though, if you're hauling around say 100lbs of battery (with today's technology this actually isn't enough, you would only get around 200hp out of this), 100lbs of generator (this is being very generous, even a single rotor wankel generator is probably going to be more than this all in), 50lbs of gasoline, then another 200lbs of electric drivetrain, you could easily have a gasoline engine putting out similar power for the same mass.
A mild hybrid runs the engine less efficiently but has less drivetrain losses, and it can produce near peak power continuously. The gasoline engine's low end torque can be completely ignored, making it better at producing max power, and you get the benefit of hearing glorious engine revving noises.
I've posted about Freedom Motors a few times around here, their ideas are surprisingly simple, but the ceramic seals are probably the dealbreaker cost-wise. 1.5hp/lb is an underestimate because that's rated at only 4500rpm (the power should be climbing past 8000rpm). You'll notice that the "high power configuration" is more like 2.5hp/lb, and that's at 7500rpm. If Mazda is getting into this game though, then there's hope that they've made more affordable long-lasting apex seals and reduced oil consumption.
Wankels really are a great fit for racing because they're mechanically simple, compression ratio is geometrically limited (so it's naturally biased towards high-load efficiency) and high-rpm efficiency is good if you add more spark plugs (much easier than adding spark plugs to a piston engine or jet ignition or multi-point laser ignition).
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