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Ken, my calculations indicate that a 2 rotor (13B) would need to turn approx 8800 RPM to produce 250 HP at sea level. Now if you use a turbocharger and run modest boost say around 5 psi you would still need to turn the engine around 7200 rpm to get 250 HP. Getting 250 HP in an automobile installation is much easier (you have gears) than getting 250 HP with a fixed pitch prop. Even Mazda has reduced their initial HP claims (250HP) on the Renesis to a more realistic 237 (and even that is at its max rpm nearly 9000).
My personal opinion is that if I were going to put a rotary in an RV-10, I would go with the 3 rotor. You can get 250HP with a 3 rotor at less than 6000 rpm and none of the complexities of turbochargers and at that rpm the rotor is quite happy (loafing really). Yes, they are more expensive, but by the time you turbocharged a 2 rotor properly, you would have nearly the cost of a 3 rotor.
My 0.02 worth on the subject
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message ----- From: "Ken Peck" <kenbpeck@comcast.net>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, January 06, 2006 7:59 AM
Subject: [FlyRotary] Horsepower - 2 rotor vs 3 rotor
Having read a bunch of stuff on this forum and other places, one question still nags in the back of my mind.
I'm building an RV-10, Vans recommends a Lycoming 540 producing 210 - 260 HP. When considering the possibilities of a Mazda rotary, obviously the ultra sexy choice is one of those 3 rotor 20b's. But in a recent post Bill Dube pointed to a Renesis RX8 13b 6 port engine on e-bay where the seller states 250HP.
You know where I'm going....
Can a 13b built and configured to put out that HP in a RV-10 last, be happy, etc.?
--
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