For those of you who love speed, S&S has come out with a new product. It's not for me as my bike goes as fast as I need but for some this product may be of interest. By the way, I have nothing to do with S&S.


http://www.sscycle.com/feature/featureview.php?s_id=58

 

From looking at the dyno chart they show, I see no value added unless you like to drive around at >5000 rpm.
Below that, it is much the same as the stock throttle body, if fact slightly less TQ through most of the RPM range.
They only gain 1 ft/lb of torque and 5 hp in the upper ranges.

Am I missing something here?

 

the reduced low rpm performance is typical of "too large" a TB- the velocity of the incoming air is lower than other wise.

possibly resulting is less cylinder fill, less turbulent mixture in the cylinder.

but gains from 4800- 6500 RPMs.

for any performance gee-gaw the question must be asked "in what rpm range do I do most of my riding"


unfortunately S&S does not give other details of the motor build dyno'd

the "too big" was often a problem on carb vehicles as well whether a harley or a car, in this case the air velocity was too low to draw fuel from the float bowl- so oversize jets were used to supply more fuel- which would not atomize and would burn unevenly. Once the rpms were up and the air moving the jets would now be too ;large and the mixture over-rich.

(the beauty of the constant velocity carb like the SU or Keihin CV is in the design)

 

I have a SE 58mm TB that I'm not using right now because I was told by the builder I would loose some low end torque, funny thing is I paid less for my TB than S&S wants for exchange, go figure.