Sent: Wednesday, September 17, 2003
11:01 AM
Subject: [FlyRotary] Intake
questions
Greetings,
I'm probably about to
prove that I haven't paid any attention to any of the intake construction
threads, but here goes... I know there's special length that will tune
the intake to make more power. Ed knows what this is, but if he tells
us, he has to kill us (a slow painful death, involving 60 slides)
:-)
power band, so I started wondering if I could
"tune" it with individual pipes on the inlet side of the
TB.
Thanks,
Rusty (Scotty, I need
more power!)
Hi, Rusty.....I
purchased the short intake manifold from Dave Atkins. He claims he has more
than adequate power with his, and that idle is also good. Look at all
the race cars and racing motorcycles that have the carbs or throttle bodies
right next to the engine. They seem to generate a lot of power that
way. For what it's worth.
Paul
Conner
Paul is correct. There
are any number of intake configurations that will produce adequate power for
the RV-6. I am told that Dave Atkin's intake permits him to generate
approx 160HP which is certainly adequate for an RV and could even provide
thrilling performance in a low weight RV
I'll have to
say I've flow an RV with adequate (whatever that means)
performance while producing as little as 120HP. The cruise
was around 180 TAS which was adequate because even today I generally
elected to cruise at 170 TAS to conserve fuel, but take off and climb with
120 HP in my somewhat heavy bird were agony!
Paul, not
disputing what you say at all, but you have to consider the different
application. you are making the same assumption that I made
with my first intake. Yes, I listened to the Racing guys and I'm
certain that their advice was just peachy for racing - if you are turning
over 7000-8000 rpm. Than rpm range means short runners and large
diameter inlets are the cats meaow.
But, I can tell you
from personal experience that if you think you are going to put a curise
prop on your RV-6 with that set up and think you are going to turn 7000-8000
rpm with a 2.17:1 PSRU you are going to be sadly disappointed. Tracy
Crook turns as high an RPM with that set up as anyone I know (has hit 214
mph TAS) and maxs out at around 6400 rpm. His tubes are 1.25 and 1.5"
in diameter as best I recall and wrap over the top of his engine so that is
air intake sits on the top middle of his cowl. So the tubes are not
short.
The auto and
motor cycle guys have one advantage - they have gear boxes which permit them
to wind the engine up into those higher rpm ranges with a lighter load
(lower gear) before shifting to the next ratio (where you do indeed generate
more power), but we can't wind our engine and then shift gears (at least not
yet).
Bill Eslick initially
use a very short induction system which provided very disappointing
performance results. His report (earlier on the list this
week) indicates that once he went with a different (read - longer
intake, copied after Tracy's as was mine) his performance improved so that
he now keeps up with the 160 HP Lycoming powered RV-6s.
You have to select the
induction system parameters that is realistic for your
application! What sucks for us - works for the race guys, what works
for us -would suck for the race guys. Its like apples and oranges (so
to speak) {:>)
Now, I will be the
first to say, if you want to experiment or if you find for cost,
configuration or convience reasons you want to try some particular intake
configuration, please do so. I've been wrong before and I am certain
will be in the future - but, do it with your eyes open and understanding of
what performance might reasonably be expected.
Best
Regards
Ed
Anderon