Paul,

One more thing...

I flew the Lancair on Saturday and ran it WOT in cruise mode to see what
effect the p-port motor might have had on my "economy cruise" speed.  TAS
with the original side-port motor was 158-159 kts burning 11.4 gph; TAS with
the p-port motor was 170-171 kts burning 14.0 gph.  She may have another few
knotts in her as I didn't hold it straight and level for very long.  All in
all, a gain of 10-12 kts is not too bad, if you don't mind the higher fuel
consumption.  Data was taken at 4500 msl at about 75*F, 1700 rpm on
prop/5200 rpm on the engine.  Oil temp was 185*F.

With the original side-port engine, top speed was achieved at around 6800
rpm.  But I don't think my new intake is tuned for making max hp/torque in
that rpm range.  The runners are 27" measured from the bellmouth to the
rotor face.  I would prefer the hp to peak around 6500-7000.  Wouldn't that
necessitate a runner length of around 21 - 23"?  That would be a pretty easy
modification to make.

Mark

Mark S.

159  kts 11.4 GPH 183 MPH 16 MPG
171  kts 14.0 GPH 197 MPH 14 MPG

Beats a sport Ute at 80 MPH :)

My C182 is 150 MPH at 11.5 GPH or about 13 MPG.

If you want max HP. Max HP lags max torque by several hundred RPM.
I think it should be around 21 to 23 but make it adjustable.
That gives max torque at about 6000 RPM and max power at 7500 RPM.

You need to record fuel burn over a wide speed range
....say every 10 kts.... so we can plot MPG :)

Paul Lamar


Assuming no significant aerodynamic changes to the airframe, I believe
that represents a very significant increase in horsepower..  Maybe
about a 24% increase in power to get from 159kts to 171kts - a 7%
increase in speed.  It sounds like you're only burning about 14% more
fuel, so that's a deal, all else being equal.

I'd be interested in seeing the fuel burn at the old 159kts to get a
measure of the improved efficiency due to reduced pumping losses..  Or
said differently, how fast does it now go on the same fuel flow as
before.  For comparison, it would be good if the peak-power RPM were
optimized to be the same as with the old intake..


Matt-

Mark,

I'm curious, what kind of instrumentation are you using to measure fuel burn and do you have a fuel injection with a fuel retun line?
Thanks
C. Smith