[Christ]

Mech - Please, don't think I was attacking you personally. If you've come up with a way to use a generator in the intake stream, please, by all means, go for it.

As with any new technology, there will be nay sayers. In this case, I'm one of them. Mathematically, there just isn't that much energy to be extracted from the intake's volume at ANY RPM, let alone at idle, as I calculated.

There is another formula that I can use to show you exactly how much energy a given cross section of wind contains:

P = 0.5 x rho x A x V3: Power in the area swept by the wind turbine rotor: (This doesn't necessarily imply that you're using a wind turbine, it's just the power contained in the cross section of flow.)

Once again, we'll assume as many ideal circumstances as we can, to give the best possible chance for a good result. We're also going to use the influx of an 8.0 liter engine at 6,000 RPM, assuming 100% VE, for exaggeration's sake:

P = 0.5*1.225 kg/m3*0.008 m2*0.4 m3/s (847.552 CFM)

0.00196W - This is the total amount of energy contained in the volume of air that is necessary for that engine at the quoted RPM and displacement.

For simple comparison, a 10 foot blade span (20 foot diameter swept area), using the same CFM figure, contains:

P= 0.5*1.225 kg/m3*29.2 m2*0.4 m3/s

P= 143.08W, or 0.2 HP.

Remember - air is a constant in science, and wind is a battery. Air holds potential energy, wind contains kinetic energy - kinetic energy had to be given to the wind by something else, so the wind is a battery of energy which can be extracted. Air is not very dense, thus, requires very little energy to move a given mass at a given speed. Per Conservation of Energy, when very little energy is passed into an object, very little energy can be extracted from it.

According to Albert Betz, no more than 59.3% of the energy in the wind can be extracted by means which require the energy of the wind to move an object to convert energy. If no conversion can successfully be more than 60% efficient, of the 143W in the second example (20 foot diameter), you can only successfully get ~57W. On top of that, there are generation losses from heat and friction, further reducing the amount of energy that can be extracted.

Adding to all that - If you extract the Betz Limit of energy from 800 CFM, you're only left with a flow rate of approx 320 CFM, which is much less than the requirement to keep the 8 liter engine at 6,000 RPM and 100%VE.

While the project in question would be able to operate as an engine brake by extracting energy from the intake stream, very little power would be generated by it, and almost none that would be useful over a short period of time.

Keep in mind - I'm not saying that you can't use a positive displacement pump to charge the intake air, thereby creating forced induction - I'm just saying that the process won't work in reverse, according to currently understood physics and fluid dynamics.