Alternator on a turbo
in [Toyota]
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From: Scribe on 25 May 2010 14:44 I read that an experimenter fitted an alternator onto a turbo and got free charging from the exhaust. This seems like a very logical and obvious thing to do, and must raise mpg and no fan belts to snap. A beefier alternator and a larger battery could run electric a/c as well, by using waste energy from the exhaust. Has anyone ever seen such a conversion?
From: C. E. White on 25 May 2010 15:53 "Scribe" <Scribenospam(a)nospam.com> wrote in message news:hth5qj$37u$1(a)news.eternal-september.org... >I read that an experimenter fitted an alternator onto a turbo and got >free charging from the exhaust. This seems like a very logical and >obvious thing to do, and must raise mpg and no fan belts to snap. A >beefier alternator and a larger battery could run electric a/c as >well, by using waste energy from the exhaust. > > Has anyone ever seen such a conversion? I've never seen one. The energy derived from the turbo won't be entirely free. Adding the turbo will increase back pressure and potentially lower performance and mileage. Turbos don't run at a "fixed speed" relative to demand or relative to exhaust gas volume available. When electrical demand is very low and exhaust gas flow is very high (like at wide open throttle when accelerating hard), the turbo might spin at very high RPMs. If the electrical demand is high and the exhaust gas flow is very low (like at idle) the turbo might spin very slowly (so slowly it won't charge at all). The normal rpm range for a belt driven alternator is maybe 10 to 1 (high to low). For a turbo driven alternator, it might be 100 to 1. This makes for a difficult design. To overcome this you could introduce some sort of waste gate or governor to regulator the speed of the turbo, but now you are making things much more complicated. I think you would need a specially designed lower speed turbo (current turbos spin at high speeds to more efficiently drive the attached centrifugal blower). I also think you will need to include some sort of governor or waste gate to prevent the turbo from turning too fast. The presence of the turbo will increase back pressure which will reduce mileage and maximum power. In the end I think you will end up with a very complex system that won't improve your mileage by any measurable amount. But, if you design one, let us know how it works! Ed
From: Hachiroku ハチロク on 25 May 2010 15:55 On Tue, 25 May 2010 19:44:26 +0100, Scribe wrote: > I read that an experimenter fitted an alternator onto a turbo and got free > charging from the exhaust. This seems like a very logical and obvious > thing to do, and must raise mpg and no fan belts to snap. A beefier > alternator and a larger battery could run electric a/c as well, by using > waste energy from the exhaust. > > Has anyone ever seen such a conversion? It still takes energy to turn the rotor. This means it's taking away from the efficiency of the turbo. Also, it takes a fair amount of exhaust pressure to spin a turbo. What happens at stop lights, grid lock, etc? I think this might fit the Urban Legend category, unless the guy lives in an area like I do with not a lot of congestion, and only drives during the day...
From: C. E. White on 25 May 2010 18:53 "Hachiroku ハチロク" <Trueno(a)e86.GTS> wrote in message news:iXVKn.21674$mi.9405(a)newsfe01.iad... > On Tue, 25 May 2010 19:44:26 +0100, Scribe wrote: > >> I read that an experimenter fitted an alternator onto a turbo and got >> free >> charging from the exhaust. This seems like a very logical and obvious >> thing to do, and must raise mpg and no fan belts to snap. A beefier >> alternator and a larger battery could run electric a/c as well, by using >> waste energy from the exhaust. >> >> Has anyone ever seen such a conversion? > > It still takes energy to turn the rotor. This means it's taking away from > the efficiency of the turbo. > > Also, it takes a fair amount of exhaust pressure to spin a turbo. What > happens at stop lights, grid lock, etc? > > I think this might fit the Urban Legend category, unless the guy lives in > an area like I do with not a lot of congestion, and only drives during the > day... Here is an idea - use the exhaust turbine driven alternator to power the electrically driven supercharger...that's the ticket! Two scams packaged into one awesomely worthless creation! Ed
From: Hachiroku ハチロク on 25 May 2010 21:37
On Tue, 25 May 2010 18:53:43 -0400, C. E. White wrote: > > "Hachiroku ハチロク" <Trueno(a)e86.GTS> wrote in message > news:iXVKn.21674$mi.9405(a)newsfe01.iad... >> On Tue, 25 May 2010 19:44:26 +0100, Scribe wrote: >> >>> I read that an experimenter fitted an alternator onto a turbo and got >>> free >>> charging from the exhaust. This seems like a very logical and obvious >>> thing to do, and must raise mpg and no fan belts to snap. A beefier >>> alternator and a larger battery could run electric a/c as well, by >>> using waste energy from the exhaust. >>> >>> Has anyone ever seen such a conversion? >> >> It still takes energy to turn the rotor. This means it's taking away >> from the efficiency of the turbo. >> >> Also, it takes a fair amount of exhaust pressure to spin a turbo. What >> happens at stop lights, grid lock, etc? >> >> I think this might fit the Urban Legend category, unless the guy lives >> in an area like I do with not a lot of congestion, and only drives >> during the day... > > Here is an idea - use the exhaust turbine driven alternator to power the > electrically driven supercharger...that's the ticket! Two scams packaged > into one awesomely worthless creation! > > Ed There was a guy around here that had an older Cadillac with what looked like a jet engine on top of it. He had cut a hole in the roof, and the 'fan' from the contraption turned a shaft, and a belt through the hole in the roof spun and alternator set up in the back seat and charged a spare battery... Yup. It looked just like it sounds... |