Forced Air? TURBO? Options

[bob91403]

Could someone tell me why a scoop can't increase air pressure, as you go faster, and create the same kind of HP "boost" you get from turbo or superchargers? Excuse me for being ignorant. But, isn't it just a matter of increasing air pressure to the intake, and pumping in the right amount of gas for mixture? What about a pressurized tank of air, or both air and propane tanks? Couldn't you use a small compressor for boost, or as a source to refill a "boost" tank? I really don't understand this obcession with tubocharging. Nitrous systems have been around for a long time, and are much simpler. I was told, by my top rated Porsche mechanic, that, "Yeah, higher compression heads, turbocharging, supercharging, nitrous oxide, will all increase horsepower. But, anything you do to increase the horsepower will seriously lower the longevity of the engine." He doesn't even recomend european compression heads for a rebuild. I do understand, tubocharging a smaller engine gives you increased horsepower, plus the weight advantage of not having to put in a 3.2L six. But, if you have to rebuild it every 50K, instead of 150K miles, doesn't conversion cost less? Curious to hear your replies.

[airsix]

Could someone tell me why a scoop can't increase air pressure, as you go faster, and create the same kind of HP "boost" you get from turbo or superchargers?

You can't compress air against a surface (scoop) unless the velocity is supersonic (your car would have to go about 700mph). Below supersonic speeds the air just moves out of the way without being compressed.

What about a pressurized tank of air, or both air and propane tanks?

Ok, there is about .07 cubic feet in 2 litres. I have an 80 cubic ft scuba tank (big heavy tank, 3,000psi). If you only provided air to a 2.0 engine at atmospheric pressure that's good for 80x.07x4cycles-per-revolution = 4,571 revolutions of the engine. If you're averaging 4,571 rpm then you're good for exactly 60 seconds. That aint much, and you were'nt even using "boost", just suppying air at atmospheric pressure.

Couldn't you use a small compressor for boost

This comes back to the "electric supercharger thread. How are you going to power the compressor? It takes serveral horsepower to power a pump with enough capacity to provide forced induction. It doesn't matter if that pump is powered by exhaust gas, direct drive, or an electric motor. All of those methods require the same power INPUT give or take, and you can't supply several horse power with your alternator. Even if you could it would be much more efficient to use direct-drive. Any time you convert one form of energy to another you loose a bunch of energy. So going from mechanical engergy (belt drive) to electrical engergy (alternator) and back to mechanical engergy (pump) your losses are huge.
Look at how race cars make power. Cubic inches, high rpm, and forced induction via turbo or supercharger. If electric fans or compressed air tanks worked they'd be using them.

-Ben M.