Should be an interesting experiment Paul, can't wait to hear
results.
I tried a very short and now a medium-short manifold and find
that it works well IF it is very "clean" (proper diameter runners, no change
in cross sectional area, well matched to ports, etc, etc) The very
short runners gave up some power at climb rpm (FP prop) but did OK at cruise
& top end. The Medium-short version works about as well as my long
(so-so clean) manifold (~17" runners) and real good at top end.
FWIW, my guess about your dripping throttle body is condensation on the
runners & throttle body walls. Gravity does the rest.
Agravating the problem is the "cool side injectors". Someone called
this arrangement the "Holy Grail" of intake design. I'd call it
the "Sacred Cow".
Tracy ( eat sacred cow for lunch).
Cut
Hi, Tracy....I have tried the short manifold,
and I love it. I left everything undisturbed except the manifold, a
shorter throttle cable, and longer wires to the injectors/throttle
position sensor. The engine started fine (as it did with the longer
intake runners). That's where the comparison ended. With the same
factory default settings on the ECU, the transition from idle to midrange
was oh, so smooth. I used to think the long intake manifold had a smooth
transition...until I tried the short Atkins intake manifold. A world of
difference. With the long intake runners, I could not advance above
1/2 throttle without the engine bogging down. Now, I can go to full
throttle, and the brakes will not hold. Smooth from idle to full
power. The best part....no after shutdown fuel drips at
all. With my 3 blade 64 x 78 prop, on three trials, my static
rpm's were 4800, 5000 and 4800 rpm's. Don't know what rpm I will get
once the prop unloads in flight, but it is such an improvement over my
long intake runners that always dripped fuel after shutdown. I am
finally excited about this aircraft. It's climb performance was more
like a Cessna 150 with the 4200 rpm's I was able to obtain on it's first
flight, and downwind only provided 140 knots (didn't retract the
nosegear). I am optomistic that the additional static rpm's I am now
getting should make a pleasant increase in performance. I have to run a
few more wires around and away from the alternator belt, put adel clamps
on the new fuel lines and finish installing a shorter throttle cable, then
I will be able to fly it and see how much of an improvement I get.
There is no doubt that I have a lot more power (since I can now go to full
throttle). Take care....Paul
Conner