I just finished reading this entire thing and now my head hurts. What George is saying is simple physics if you just stop to think about what happens in your turbo. Now I don't have years of experience working with turbos, compressors, turbines, fans or anything close, but I do have a good understanding of physics (without all the fancy lingo
).
First off George is in no way saying that your run of the mill electric (or gas for that matter) leaf blower is going to come anywhere close to doing what your low end/cheap/stock/high end/whatever turbo you've got on your car will do. He is simply saying that increasing the airflow (and therefore the manifold pressure) will help no matter how small it might be.
Now lets cover some of the arguments that have been made here. We need to keep in mind that we are comparing apples to oranges here, so when trying to make a comparison it helps to try and equalize the equation. Realize that your turbo has been designed to do everything much better than the leaf blower. It is much more powerful, built with much higher tolerances, built to last much longer and therefore it also costs much more.
Could an electric turbo be made that makes the power that your current turbo does? Sure it could be. Replace the impeller that sits in the path of your exhaust gases with a big electric motor and bingo, you're golden, right? I suppose advantages would be that you have more control over the speed of the compressor and you could locate it in a more convenient place. The downside is it's FAR less efficient than your traditional turbo. You need a larger alternator to supply the current needed (weight and energy loss via heat), larger wiring to carry the current (more weight + heat + energy loss), and then the large electric motor on the turbo (even more weight and energy loss via heat). The question is why would you want to do that when we already have a better alternative?
Now for a new way of thinking about the solution that George is offering with the leaf blower. We have a 350 that flows ~500 cfm at 5k rpm. That puts the manifold pressure at some negative number. Instead of putting the 400cfm leaf blower in the already existing intake, lets just add another hole right on top of the intake manifold. Now the leaf blower isn't going to get in the way. Hey I have a better idea! How about instead of your normal intake, we change it to ram-air! Now you have your extra pressure at low rpm and at high speeds. ghetto rigged? Well yes, maybe =) But we don't want to spend the money on a turbo to do it right now do we?
It's late so forgive my rambling. One more thing to address though.
Lets talk about pressure. What is pressure? Everyone here seems to be thinking of pressure as something bottled up. Pressure in a hose, pressure in a tank, pressure in a bottle, pressure in the intake manifold... Well, when a fan is spinning, why does the air move? Because as the vanes move through the air on one side the air is compressed, while on the other side there is a slight decrease in pressure. The weight of the air in the atmosphere pushes air in to replace the air behind the fan blades, while the higher pressure air in front of them expands to equalize, creating that nice breeze you feel. Sailboats use pressure from the wind to move. Extremely low pressure over a very large surface area equals a very large force. See what that low pressure difference making a 60 mph wind does to a sailboat.
Centrifugal fans work differently, they spin the air and use centrifugal force to move it. As the air is 'slung' outwards a negative pressure is created in the void where the air used to be. Again, atmospheric pressure forces air to replace it, which is then slug outwards and the process repeats itself, creating the airflow you feel.
There was a lot of talk about 'stalling' blowers and turbos. I think covering the outlet of your turbo with your hand is a bad example. You've got a lot of force driving the turbine that is pushing the air out and I don't think anyone is going to be strong enough to stop that. I think it would be better to imagine what would happen if you COULD stop it. For the sake of the argument, lets forget that we want to use the air coming out of the turbo to make our engine perform better. Lets just say the engine makes 200 hp without the turbo, and we just hooked one up to it to see if we could stop it. Without a waste gate (that also messes with my theory) if the engine has enough power the same thing would happen with your turbo as happens to the leaf blower when you put your hand over the outlet. It will reach a maximum pressure and then fail to make any more pressure. If your engine isn't strong enough to continue to drive the turbine at this point it's likely you'll stall it due to the lack of a place for the exhaust gases to go. I imagine having that happen depends on many different factors such as engine speed, angle of the turbine blades, and some other things I can't think of right now - but it would be an interesting experiment!
And finally, for the original poster - Why not just invest in Nitrous for the power on demand application your looking for? Cheap, lightweight, fairly safe and big horsepower gains.
If anyone has made it this far I commend you! I will end my ramblings here. Good night all!
-Randy