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| Turbocharger power input (consumption) |
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| langwadt:
--- Quote from: Circlotron on March 25, 2020, 10:32:41 pm --- --- Quote from: langwadt on March 25, 2020, 09:38:41 pm ---it is not quite so simple, the turbine is driven by the kinetic energy of the exhaust stream not just pressure --- End quote --- It sure isn't simple! I've often wondered about the effect of having a large plenum right at the inlet to the turbine similar to one commonly used at the compressor outlet where the inlet pipes branch from. That would spread and reduce the amplitude of the kinetic energy of the pulsating waves to more of a smooth flow, similar to the effect of a series choke with rectified DC current flow. The turbo might have to be resized to suit the new circumstances, but I wonder if there would be any benefit. Somewhat similar to a transformer not having to handle the peak currents of a capacitor input filter? Far fetched maybe, but sometimes physics has some interesting parallels. --- End quote --- kinetic energy is velocity squared so I think it'll reduce power |
| joeqsmith:
--- Quote from: Circlotron on March 25, 2020, 08:47:57 pm ---Also, I wouldn’t say the power to drive a turbo is free. If you have pressure at the compressor outlet then you are also going to have pressure at the exhaust turbine inlet. This exhaust back pressure is something the rising piston has to push against on the exhaust stroke, therefore stealing crankshaft power. Of course, this might be partially countered by the inlet boost pressure helping to force the piston down on the inlet stroke. To get it right is engineer’s stuff, not a shade tree mechanic. --- End quote --- I try to match this at 1:1. So 30 PSI on the intake, 30 PSI in the exhaust. To measure the exhaust pressure, I use about a foot of stainless tubing to connect the sensor. With higher pressures, I have had the valves want to open. Of course there have been many other problems to solve along the way. |
| NiHaoMike:
In the realm of racing, how does a turbocharged/supercharged engine compare to a jet engine? |
| langwadt:
--- Quote from: NiHaoMike on March 25, 2020, 11:11:54 pm ---In the realm of racing, how does a turbocharged/supercharged engine compare to a jet engine? --- End quote --- jet engines are powerful for their size and weight, but thirsty and only really efficient at +90% power |
| Someone:
--- Quote from: NiHaoMike on March 25, 2020, 11:11:54 pm ---In the realm of racing, how does a turbocharged/supercharged engine compare to a jet engine? --- End quote --- Mechanically they have a lot of similarities. Scrapheap challenge showed at least 2 DIY jet engines based around turbochargers: https://youtu.be/z0iigOmActU https://youtu.be/9GCBCdMOFpE Rudimentary antilag systems basically use the turbo directly as a jet engine... --- Quote from: unknownparticle on March 25, 2020, 04:47:06 pm ---Guy in the UK, can't recall the name just now, used an interesting method of eliminating turbo lag on his Ford BDT (If I recall correctly) powered hill climb special. He used a jet turbine APU to assist driving the turbo, so the turbo had a constant feed of exhaust gas, therefore boost was constant!! The thing is crazy fast off the line, as it is also AWD, and everywhere else!! Not exactly practical or fuel efficient for road use, but for it's intended use, amazing. I've watched it run a few times and it's quite an experience, with the sound of a jet engine and a 4 cylinder turbo motor. Oh yeah, he built it all himself!! --- End quote --- Antilag has many implementations: https://en.wikipedia.org/wiki/Antilag_system |
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