tooter's manifold adventure... - Toyota Yaris Forums

CrankyOldMan · 06-17-2012, 10:30 AM

One other solution to the side-mount TB is to use a tapered plenum:

As far as runner length, all of the material that I have read insists that longer runners = low end power and vice versa. This is all based on the Helmholtz resonator theory. If you look at the first equation (relax, you don't have to solve it) you can see that the mass of air in the neck is in the denominator, meaning that larger masses of air (longer runners) will decrease the resonant frequency (RPMs). Increasing the cross sectional area will increase the frequency, as well as have a slowing effect on air flow velocity in the runners. The variables for the 'cavity' refer to the cylinder, not the plenum.

tl;dr - science says long runner = low rpm boost. Unless this article has empirical evidence to back up their claims, treat it as snake oil.

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06-17-2012, 10:30 AM	#11
CrankyOldMan 2ZR swap. DO IT! Ask how! View User's Garage Drives: 09 Meteoric Metallic HB Join Date: Feb 2011 Location: West Michigan Posts: 2,333	One other solution to the side-mount TB is to use a tapered plenum: As far as runner length, all of the material that I have read insists that longer runners = low end power and vice versa. This is all based on the Helmholtz resonator theory. If you look at the first equation (relax, you don't have to solve it) you can see that the mass of air in the neck is in the denominator, meaning that larger masses of air (longer runners) will decrease the resonant frequency (RPMs). Increasing the cross sectional area will increase the frequency, as well as have a slowing effect on air flow velocity in the runners. The variables for the 'cavity' refer to the cylinder, not the plenum. tl;dr - science says long runner = low rpm boost. Unless this article has empirical evidence to back up their claims, treat it as snake oil.