----- Original Message -----
Sent: Friday, September 19, 2003 8:13
AM
Subject: [FlyRotary] Re: Whats good for
Racing is necessarily good for aircraft was Re: Intake questions
This may be just side commentary and a useless
data point, but for what it's worth here is another somewhat different
comparison. Also I've copied Jon Lauter on this because he must have some more
knowledgeable input. I have one of Jon's Rotary Power Marine engines in
a boat. (Cut that laughter right now). He rated it at 175hp and has a short
manifold to a carb just above it on the intake side of the engine (also
distributer ignition, turbo block and rotors).
My "dyno" comparison is with the previous engine
a 150hp johnson outboard (Will you guys cut that out?) The current
installation must be well over 100lbs heavier due to the conversion from an
outboard to a stern drive but turning only 4500 I'm the same speed as the 150
hp so I feel pretty comfortable that should I let this get up to 6500 I'd have
that 175. Pretty scientific, I know.
Hopefully Jon will respond.
By the way, it is really nice cooling a boat
engine!
Peter
I agree, Peter - Jon sells an excellent
product. At one time (when having problems with my initial 1986 block) I
contacted Jon and was on the verge of buying one for my umm errr Air Boat
{:>) I have NO Doubt that at 6500 rpm you are getting 175HP. At
that RPM with a good intake and right air/fuel mixture you could
possibly get in the 190-200HP range. However, I am willing to bet
good money, that if you took that engine and my prop and 2.17:1 gear box, you
would never see 6500 rpm. You would probably see in the 5900-6100 rpm
range.
I repeat - there is no doubt that short fat
stacks are good for High RPM power (<7000 rpm?). But to produce
that power at that RPM you have to be able to get to that higher rpm. If
you have gears or low loading from a low pitch prop then you can probably do
it. However, if you do not have gears and have a heavy load then its
likely that your will find your load = your HP being produced at some
point long before those High RPMS, which if that happens - you will never see
the higher rpms and the HP they promise.
Ed Anderson