bascho

I was having two thoughts at once....sorry for the confusion. Electrical generators driven by air create completely free electricity (windmill). However, you are correct, a generator driven by engine exhaust gases is created at the price of back pressure.

The heat issue is less of a concern because I am talking about the exhaust-driven turbine having a pulley on it which would drive the accessories in the same fashion that the crank does. The question is, would the gain from no parasitic accessories on the crank overcome the loss created by the increased backpressure. I am not smart enough to figure that out.

cekim

Well, its not "completely free", but the cost is not measureable in meaningful terms, so I'll give you that one Put enough of them up and you start screwing with the weather - but that's a pretty big wind farm...

If you already had a turbo (and therfore got the benifit from it on the combustion side), than this might be interesting in the academic sense...

That said, "pulley" and turbo don't go well together for a number of reasons...

1. heat - rubber and turbo temps don't get along - so you'd need some sort of shaft (anyone who has heard "shaft" and "turbo" same sentence before feel free to cringe now)...
2. speeds - impeller speeds of turbos are very high - so you'd either need to gear it down or have a very inificient pump mechanism that did little per revolution - in either case - lots of loss...

Back pressure is a big issue on an N/A motor and even without goign through the specifics, I would be willing to bet that the loss there would be significantly larger than the loss from accesories...

On a forced induction motor backpressure still matters, but in percentage terms, loss/optimization there is less noticeable in the face of drastically improved combustion efficiency...

So, to even consider this, I think you have to assume you have a turbo, not just a gas driven accessory bundle. Then you have to get past the speed/heat issue which is profound...

bascho

You make some great points....like I said, I was just brainstorming. I'm sure someone somewhere along the line has thought of this, tried it out and determined it to be not worth the effort. Thanks for the insight!

cekim

People have been patenting or trying to patent "perpetual motion" machines since the first days of the patent office - it seems E=mc^2 is still in effect for now...

Conservation of mass and energy has beaten up a lot of well intentioned noodlers...

Not a horrible idea to keep looking for inefficiency though - so many things are driven by near-term costs and materials science rather than theoretical maximum efficiency...

MBDiagMan

Here you go again, refuting the laws of physics that you SAY that you learned in High School! If that windmill is attached to solid ground then the energy is indeed not costing any torque from the engine. Of course, dragging the power wires from that, lead to that windmill will certainly provide resistance to motion. Oh, you mean attach the windmill to the car? If that's what you're saying, then again you are ignoring laws of physics, because that would create vehicle drag which must be overcome with? You guessed it, engine torque.

An exhaust driven turbine, if done correctly COULD provide free energy, as long as the use of the word FREE is in the context of engine torque, not greenback dollars.

Before everyone gets COMPLETELY wrapped around the axle over all this, let's go back to the original context of the original post. The original poster was apparantly under the impression that using an electric water pump would decrease parasitic crankshaft torque loss and again apparantly did not realize that this would increase the torque drained by the alternator for a net loss given the efficiency losses of the alternator and the electric motor. My original intention was only to point this out.

There is a way that this could work for a net gain, and that would be to use a switch to disconnect the alternator for power runs. It's not something that I would pursue for such an infinitessimal gain, but it would provide a net gain. I do believe, however, that there are many more cost effective methods of gaining fractional torque improvements.

billyjo

ok i have an idea, and if i missed someone saying this i am sorry. IF you add an electric water pump( which i was thinking of doing) why dont i at the same time add a more power producing alternator to compinsate for the added drain of electrical power. You add this when you add larger sound systems. Any comments on that. thankyou

CrazyAl

...a larger alternator still doesn't help.

You still have to generate the electricty to run the electric pump. A larger alternator still has to generate that electricty the same way a small one does. In both cases the energy comes from the crankshaft.

Remember, an alternator doesn't magically create electricity. It is a tool for converting mechanical power into electrical power. And it is neiccisarily less than 100% effecient.

For every watt you want out of it you have to put more than one watt into it.

MBDiagMan

Crazy Al is very patient and courteous.

Suggesting a larger alternator indicates that you still don't get it. If anything, it would potentially drain even more torque from the crankshaft

Whether you have a tiny alternator, barely capable of charging the battery on its best day, or something out of a Stewart and Stevenson power generator bolted onto the engine and driven by the crankshaft, it STILL REQUIRES TORQUE TO TURN IT!!! That torque THEN is used to charge the battery. There will be a drain from the battery that will turn the electric water pump. IT IS THE SAME AMOUNT OF ENERGY MINUS THE EFFICIENCY LOSS OF THE ALTERNATOR AND THE ELECTRIC WATER PUMP MOTOR!