turbo accesories

it's be a tad anoying everytime you let off the power to loose the power steering, battery charging and coolant circulation, and especialy as when your sat in a traffic jam, with the engine ideling, so the turbine is only just ticking over, you have no power to anything driven off it,

Then you have hte problem of getting an alternator rated at 100k rpm and the likes :)

BTW, i'd imagine the 'turbo' connected to the crankshaft of prop aircraft is really a super charger??

The message from snipped-for-privacy@btopenworld.com (Smokeyone) contains these words:

The difficulty (OK, /one/ of the /main/ difficulties) would be the expense of reducing the speed of the turbine to a useful speed for ancillaries. Gearing would be noisy and expensive etc.

More sensible would be to eliminate the starter and alternator by combining them into the flywheel. One of the French firms was playing with this idea = you can use electric power as boost at low revs to reduce stalling and improve short burst acceleration (across lights, that sort of thing).

You can also allow the engine to stop since starting it is far quieter with a direct motor built as part of the crankshaft/flywheel unit. There's no particular reason once the engine's warmed up why it shouldn't stop each time you're in neutral with the clutch up and restart seamlessly as you dip the clutch.

Also you can use the same wotnot as a very high power alternator with none of the belting troubles.

Sadly - it was a French firm playing with it - which given their reputation for reliable electrics leaves me only vaguely glad it wasn't the Italians.

I think that you would simply be swapping a direct power drain on the engine (belts connected to cam/ crankshaft) for an indirect one (restriction in exhaust system) resulting in no net gain. Whilst a conventional turbo setup does drain power, it is used to supply more air to allow more fuel to be burned.

Regards, Jim

There's this common misconception that turbos use 'free' energy, otherwise lots in the exhaust. This is just *not true*. Most of the energy which drives the turbine comes straight from the engine, as pumping losses. Only a very small portion of it is in fact 'recovered' from the exhaust, and would otherwise be lost.

I'll drop that idea then

Smokeyone

PS The old piston engines had a supercharger as well for the intake. The turbo was on the exhaust side and transfered the power to the crankshaft through a fluid coupling.....

Smokeyone ( snipped-for-privacy@btopenworld.com) gurgled happily, sounding much like they were saying :

Sounds more as if it was taking power from the crank, and using it to help evacuate the spent mixture.

The message from Adrian contains these words:

I'd be surprised if it was necessary at high altitude - particularly with the stub exhausts on things like the Merlin.

The turbos do pick up 'free' energy or 'work' against the turbo blades from the exhaust gasses. The gas is of medium high pressure that otherwise would just expand and cool into the atmosphere. Similar to a power stations that have three stages of turbines for extracting energy from high, medium, and low pressure steam.

Or more likely, same air and fuel to be burned but at lower rpm; less engine stress and noise, more relaxed driving.

The message from Johannes H Andersen contains these words:

But in doing so increase the back-pressure of the exhaust system - so it ain't free.

But the big pressures are there to begin with at the end of the combustion cycle; it takes time (and space) for the gasses to expand into the free surroundings even without a turbo attached. There may be some back pressure, but major part of the exhaust energy is 'free'. Our disagreement is perhaps a matter of degree about how much energy you can recover.

Cheap would be better word