The problem with that much extra air rushing into the engine all at once is that you need a way to meter it so that your injectors can match the air/fuel ratio so the engine doesn't detonate.

When you have a forced induction setup you need to increase the fuel into the engine with either longer injector pulses, increased fuel pressure, or the activation of another fuel injector in the intake manifold. Because of the complexity of the former two systems and the idea that you want to build the cheapest system possible (the reason you have a tank of air rather than a compressor attached to the engine), I would go the route of another injector in your intake manifold that is controlled by the same switch as your "boom goes the dynamite" switch (if you catch my meaning).

The other problem is that on a compressor-type FI system there is an air filter where the air comes in, it then goes to the compressor (where it's compressed), then goes to the engine. Right now your idea is to dump pressure into the intake manifold. Because there isn't that compressor in the intake system, most of the air will blow out the wrong end and pop your air filter out of the truck rather than go into your intake manifold, so you'll need a way to keep the intake pressurized while the tank is blowing.

Another problem is the neck on the bottle of the air tank. If the neck isn't big enough, the air (although of great pressure) won't come out fast enough to give you boost. Assuming you had an air tank with the neck roughly the size of a fire hose and the capacity of say a septic tank, you might get away with it. come to think of it, you might get away with an oxygen tank. Just like the one grandma has only a lot bigger.

If I made it, here's how I'd do it:

1) Take your septic tank-sized air tank with the neck the size of a fire hose and put it in the bed of the truck.
2) Get a sweet valve to attach to your air tank that is capable of instantly opening.
3) Get a T for the system with a pressure valve.
4) Hook up the intake manifold to one part of the T, the air filter to the other, and the air tank to the third, making sure that the valve is set such that when the tank closed the intake gets air from the air filter side and when it's open the filter is blocked and the tank is open.
5) Know the airflow from the tank when it's open and how much more that is from the N/A air flow. This is going to take calculus to figure out the right answer because it's not a constant pressure. As all the air rushes out of the tank, the pressure will change over time. The reason say a stock MAF won't work is that it probably can't meter that much air. If you got say a wideband O2 sensor you'd be in good shape but you'd need a computer system to take the input from that sensor and deliver the correct amount of extra fuel.
6) Put another fuel injector in the intake tube after the air tank, before the manifold and set it so that when you hit the button it delivers the extra fuel needed so the engine doesn't explode.

If you did that and got it all set up right, you should be able to hit the button and rock. You should be able to pretty easily figure out if the engine/drive train can handle the added stress when you figure out the answers to the fuel equations, they'll pretty clearly tell you exactly the power you'll make. Seems easy enough. Good luck finding the tank, that's really the only hard part.

 

You would need a trailer to carry an air compressor with you to keep the tank pressurized.
Just spray it and go have fun.

 

You sound like you know what your talking about with the turbos, other then how expensive they are to buy and install(unless you do all the fab work yourself)
But I think you should do some more research on supercharging. Because your way off on the positive displacement blowers.

"Little to gain"? OK

 

There is a lot to gain but, most people do not have the ability or money to build a proper engine to be used with a good Roots system. Most just want to slap something onto their engine and go drive the crap out of it. The 6 71 and 8V 71 blowers require a good bit of prep before they are used such as clearancing and friction proofing and then they use anywhere from 25% to 50% of the hp produced just to operate.

A roots type blower is a great modifrication if you don't need to concern yourself with space for the humongous Gilmer drive belt, other drive belts for all the accessories that we all feel is neccessary, like a.c. and power steering. The lowest buck way to go for a power adder is Nitrous as long as you don't over stress the engine. It's fairly easy to install and in some cases needs little more than a tune to be safe for modest use with up to a 150hp shot But who among us can resist using all the power we have available when we're feeling sporty? The reason Nitrous has a reputation for blowing engines is that often it is installed on engines that are in poor condition and not up to the task of the sudden burst of hp that it gives. The engine blows, often horribly and the nitrous is blamed, not the idiot that was overusing it.
My idea of an engine that I would like to build and have in a hot rod would be built with a steel crank, titanium H beam Carillo type rods, forged pistons, roller cam and rockers, titanium valves and retainers, direct port fuel injection with dual injectors, 8V 71 Huffer, with a pair of huge turbos blowing into it and maybe a little spray. Just in case the afore mentioned engine ever needs a little more. That would be a good street engine for me.

If a turbo is used on the average street engine the power is applied more gently all across the range of useable power insuring a longer life of the engine and will often improve the fuel economy of whatever vehicle it is used on. Most here are more interested in the pulling power and economy of their trucks than the ability do stomp some kid in Camaro in a stop light dig.

By the way, I do have a lot of experience building and running high performance engines and cars as well as doing a bit of research on the subject.

 

Your talking about the old school BIG roots blowers.
It's a hole new ball game now.
There are plenty of simple bolt on kits out there.
Kenne Bell Company Info
Whipple Industries
Manufacturer of Supercharger kits, remanufactured superchargers and supplier of supercharger oil.

Vortech Superchargers
ProCharger Self-contained Superchargers and Intercooled Supercharging Systems
Paxton Superchargers

All of witch run on a small belt system.

Of course, pound for pound, A turbo will make a little more power because you don't need a belt to run it.

 

I'd actually really love to have power estimates from the giant bed-sized tank in the back of a truck, even if it's rediculously ineffecient, it would be funnny and fun to watch.

Someone turn this into a popular myth so someone can get mythbusters to build something like this.

 

Someone could certainly put an equation together that would tell you based on the tank size, neck size and pressure in the tank what kind of power level you can expect, provided you can keep enough fuel in the engine to maintain the extra air. I could get working on one. It might take me a couple days to do the research to figure out the realistic numbers for it since my expertise isn't really engines, but I'll give it a go.

 

this is kinda like an idea i had a while ago.
what if you put a huge (100+ gallon) air tank in your bed, and ran a supercharger.
put the air into the tank, let it cool, then once the throttle hits 90% or so, bleed air into the engine.
basically, you would need to have a valve that regulated the air flow based on throttle position.

i've also thought about the concept of reducing the parasitic losses on a supercharger by putting the supercharger on an electric clutch, like an AC clutch.

neither idea would work, but its fun to think about

 

that has been done already in the movies, with 2 examples being Mad Max's interceptor falcon, and Lone Wolf McQuade's dodge ramcharcer

 

I havent been on here for a couple years, so I pop in and this forum still continues to amaze me with the ingenious hair brained ideas that some people get in it. lol

 

Some of the stuff discussed here could qualify for the "Rube Goldberg" studies at MIT or Rutgers.

 

This is about the same as the LEAF BLOWER idea.
Reaserch supercharging and find out that intake pressure is what is built up "AFTER" airflow has reached flow limit through the head ports and valves.
Any blower type has to produce air volume flow so far in excess of what the engine uses or no 'forced' induction takes place.
Think about it. What does it take to do this?
A unit that is turned at very much over crank speeds be gear or exhaust flow driven against vanes.
Trying air volume flow by a tank cannot nearly provide enough flow for any 'reasonable' time period.
This is only half the operation. You need to add extra fuel to provide the A/F ratio rich enough to make at least 11 or 12 to 1 mixture or you burn the motor up.
Old saying, you play you pay if you don't know much about what you are trying to do first.
Good luck.

 

actually HotRod magazine did a test on the leaf blower idea. they mounted two on a stripped down Vette. it was a interestin read and actually made power gains(not major).gained a few horses, but for the cost of the blowers and supplies to hook them up they decided they could have bought a nos shot and gained major horses

 

I thought about this thread the other day when I used a wall mounted hand drier in a men's room. It was a very near new unit that made a lot of fairly high pressure air. I didn't take a pic or write the name down but instead trusted it to my infallible memory which, of course, failed. In just guesstimating I would say that it produced better than 10psi for the 15 or 20 seconds that I used it. Pretty impressive! It should be good for short bursts of power but would require a tune to richen the mixture when under boost conditions.

 

But it didn't produce anywhere near enough volume to supply an engine with 10 psi.