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30-40 HP gain is a bit of a stretch but, my personal experience is that the right intake/exhaust combination for your operating regime does make a considerable difference in power. When I switched from the racing intake to a more conservative (longer, smaller tubes) intake my rate of climb increased by 300 fpm on the first flight with the new system. My top speed increased from 184MPH to 197 MPH TAS. Of course, once I converted to the 2.85 gear box and large 75x88 prop the equation changed (for the better) once again primarily in the area of take off acceleration and climb out.
So, such things as intake/exhaust, Fuel MAP tuning and ignition timing can make a considerable difference. Needless to say at your stage, I would do a bit of playing with the MAP tuning and ignition time before undertaking any induction rework. I did go through 4 intakes before I settled on the one I am now using as giving the best performance.
In any case, now is the time to find out all those things in the first 40 hours.
Ed
Ed Anderson
Rv-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
Thanx Ed. I have a 64"Dia. x 76" pitch prop. It's supposed to be cruise prop
that is designed for 190HP and 220MPH. But you're right, it's too early to
be cutting on the prop.
What I'm really doing now is creating a game plan to get at least 180HP -
either with this engine or something else. I've got another rotary engine
in my garage that I've torn down and cleaned up for rebuilding...maybe I
will Bridgeport it or P-Port it. But before I go down those roads I'll
explore ways to get the current engine up to where it needs to be.
I wanted to fly down to David Atkins place to have them look at the tuning -
but I couldn't talk the FAA in to amending my Phase I test area by 10 miles
so I could do that. So until I fly my 40 off I'll try some things like
streamlining the intake to see if that helps. However, if I'm really at
140-150 now - it seems pretty unlikely I'm just going to find 30-40 horses
lying around (maybe that depends on how badly I screwed things up!).
I'll keep everyone posted on progress.
Joe Hull
Cozy Mk-IV #991 (In Phase1 Flight Test - 22.4 hrs flown)
Redmond (Seattle), Washington
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