Re: i want2 do this 2 my 15 montegomery ward
Since the tuned pipes work on the same principle as sound waves, there is a formula which you should be able to find somewhere that would give the proper length. Basically, a tuned pipe REFLECTS the pressure pulse from the exhaust back to the ports while they are still open. Since the bypass ports close before the exhaust, there is a mild supercharging effect as the pressure pulse blows excess scavenged fresh charge back into the cylinder.
However, since the pipes can only be one length, they function at only a narrow band of RPM. Generally, to keep pipe length manageable, the length is about 1/2 or 1/4 of the frequency (RPM). The exit of the pipe must be smaller than the inlet so the pressure wave is reflected.
These pipes generally work better on loop charged engines but will work on crossflow too.
Once you figure the rpm you want the effect at, you go to a physics book and find the wavelength of that frequency sound wave. Then take 1/2 or 1/4 of the wavelength, whichever is easier to make. Just for example: If for example the rpm you want is 5500, the wavelength of a 5500 hertz sound wave would be 4 feet. A 4 foot pipe is too difficult to have hanging off the engine so you would go to 2 feet or 1 foot. That would get the same effect from the half wave or quarter wave overtones. Now, remember, I don't know the wavelength of various frequencies so you need to look them up.
You also need to be absolutely certain that the engine is capable of reaching that rpm and must prop for it.
However, when the pipe does " come on" you will hear and feel it. But don't expect miracles: You won't gain 5 more horses and depending upon the hull, you may only gain 1 MPH. In racing though, 1 MPH can mean the difference between winning and losing.
Remember: This is not esoteric engineering. Model airplane engines have been using pipes for 40 years. They were developed by a Polish racer named Ted Wisnieuski who built upon the works of Polish physicist Felix Coanda. Technically, it should be called the "Coanda Effect." For years, Ted was unbeatable and set numerous speed records. He also developed loop charging for model airplane engines
Japanese dirt bikes borrowed this pipe technology from model airplane engine design very soon after it was developed so they have been using pipes for about 40 years too.
AND: Since air has mass and tends to keep moving at the velocity and direction it is moving, you can tune the length of the carbs and manifold for a mild supercharging effect. Remember the long and short ram Chrysler 413 engine of the 60s and 70s with two big 4 barrel carbs? It really works, but again, no miracles. Look under the hood of most modern autos. Multi-port fuel injected engines almost certainly will have tuned length intake runners. That's one of the ways the engineers get more power out of a smaller engine.
Remember the Beach Boys? --or was it Jan and Dean? Fuel injected Stingray and a 413---"He follows ram induction but it's understood: I have a fuel injected engine sitting under my hood. Shut it off, shut it off, buddy now I shut you down."
