Quote:
Originally Posted by mike-y
But you are right on the 3 stage, that there aren't alternate paths for air (like on a honda). The air still goes thru the same path, but the valves open up the different chambers and use acoustical wave pulses created by engine frequencies to increase the air moving thru the manifold.
kinda like how some cool air intakes will get a big torque bump at certain rpms, when the engine reaches the pipe's resonant frequency.
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Yes Mikey! It's all about the resonance! The single stage offers one resonance point, which I believe is about 4k RPM based on all the dyno plots I've seen on here. Now take a look at Bren's dyno on page 7 of this thread
http://www.e90post.com/forums/showthread.php?t=453274
You can clearly see the three distinct torque peaks at each of the three resonance points of the 3-stage manifold. Why would anyone want to modify this beautiful piece of engineering? Such a nice broad torque curve with great low-end response and top end power. No single stage manifold can offer such a wide torque curve. Now, I suppose if one had some big duration cams and wanted to do some serious racing, that a short runner, large diameter manifold may be preferable, but that would kill low end torque. For 99% of us, the stock 3-stage is all we need.