For a given size engine, for example a 331 Chrysler Hemi, what is the
practical effect of a larger throttle body size versus a smaller one; on
a given fuel, how does it affect bypass jet size, and metering valve
setting?
An early Hilborn for the 331 has 1-13/16 throttle bodies, and the
present one has 2-7/16. A big difference! Bound to have a big effect
on the air speed in the TB. If the smaller size was 'big enough' to
supply the engine, would the bigger size give any more power? What
would the bigger size do to mid-range torque?
I come from 40 years of motorcycle engine building, and for a 500cc
cylinder size, a 1-1/2" TB was HUGE and useful only on a pure racing
engine with power and torque only at top revs. I know, of course, that
the carb and injector are not really comparable, since the carb requires
a high air speed to suck fuel through the main jet, and the injector
doesn't.
Bill Hoddinott
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