Tom Sixkiller wrote:

[snip]

CMIIW but Lycoming's have tuned INDUCTION, not tuned injectors.

This is manifestly not true with _all_ Lycomings, but it may be true for
four bangers (but even then perhaps more as a function of marketing spin
than concerted engineering effort).

Tuning an intake system usually implies two goals: Near identical
mixture distribution and tweaks to manipulate the torque curve. For
engines that do not use port or direct injection the former more or less
requires identical runner lengths, something that may be a happy
accident on four bangers but certainly isn't the case on my O-540.
Manipulating the torque curve consists of futzing with the length and
diameter of the runners such that one of the pressure peaks in the gas
column (the gas column has inertia but is perpetually being asked to
stop and start as the intake valve opens and closes, resulting in
standing waves in the gas column) coincides with the intake valve at the
time the valve is open for a particular engine speed, such that there is
a relative overpressure during some portion of the intake valve being
open. I _might_ believe some of that was done, but lacking intake
balance pipes and other weird juju I'd be skeptical of the efficacy of
same -- and even then it wouldn't contribute to mixture distribution.

Don't even get me started on Lycoming plumbing the intake runners
through the oil pan to "improve" the mixture. If the runner design is
so bad that the intake manifold needs to be heated to assure that the
mixture from the carb remains vaporized the only reasonable conclusion
is that the runners are too long or have too many kinks and that the
overall intake system blows hairy goats. It's the mechanical
engineering answer to documenting a bug and calling it a feature.