> "Echo Lake Fishing Resort (Georges Boucher)" wrote:

  Hi! I'm a new subscriber and have a couple of questions. I'm
building a STOL Christavia Mk IV on floats (2200lbs gross) using a
1991 13b NA 6 port Mazda engine with RWS's 2.85:1 PSRU as well as
 there EC2 EFI/Ignition & EM2 Monitor. I'm considering a 2 blade
84" Ivopro Prop or a Warp Drive 72" 4 blade . Here are my
questions, I want 200 to 220 hp ( I also want reliability, not a
hand
 grenade), what kind of porting should I do street port? P-ports?
where can I get templates, I was told Mazdatrix but couldn't find
templates on there site. Second I have 38 years  experience as a
 mechanic but never had anything to do with rotaries, please critic
the above combination any suggestions would be appreciated.
 Regards.

 Georges & Gail Boucher
 2126 Creighton Valley Road
 Lumby, British Columbia
 Canada  V0E 2G1
 (250) 547-6434
 www.echolakefishingresort.com
 www.echolakefishingresort.ca

Well for over 200 HP you will need a p-port or a turbo charger.
A p-port is cheaper, weighs less and is more reliable than a turbo.
A Christavia on floats is unlikely to cruise long distances at 14,000 feet
where a turbo charger would pay off big time.

The basic 2 rotor engine is structurally good for 800 HP.

A Warp drive would probably work but a wood prop might be slightly more
efficient. Large diameter is good for low speed thrust but 84 inch
might limit the
RPM and therefore the HP. You want to shoot for about 7500 RPM for takeoff.
My guess for a first cut is keep the prop diameter down to about 76 inches.
Best to use a variable pitch prop with sea planes. An IVO prop is variable
twist which is not what you need. Also Ken Welter has extensively used NOS
in his 3000 pound Coot to get it off the water.

Paul Lamar

Ken Welter wrote:

   I have tried a 72 inch 4 blade warp drive and the one that I am now
running is a 70 inch 5 blade, the five blade will blow away the 4
blade, the best prop I have run is a 6 blade with a 3.16 to 1 redrive
but the 6 blade will not work on the 2.95 to 1 redrive I am now
running but I am working on a 3.21 to 1 redrive and will switch back
to the 6 blade, for a seaplane that needs massive static thrust the
warp drive is the way to go.
  For a 2200 lb Christavia a NA 13b will be more than enough to do the
job but I would still put a nitrous system in for those small high
altitude lakes when your at full gross weight.
  The main benefit of the nitrous is that I can set the prop pitch for
cruise and still get out of the water.
   Ken

 
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