My 601 has now flown twice with the corvair.  The first time it flew, it did not climb very well at all.   I have the warp drive prop that I bought through WW.  It was set at 8.5 degrees, as recommended.  Static RPM was at 2900.  Once in the air you had to basically maintain full power to keep it from loosing altitude.  The manual said that a flatter pitch would get you in the air but it would not be a comfortable trip around the patch.  That is what it was like.  I changed the pitch on the prop to 9.5 degrees to see what that would do.  I have static RPM of 2750.  it climbed at about 700FPM at 2800 RPM.   It seamed a bit better in the air, but still had to keep near full RPM, to maintain level flight.   Does anyone have any thoughts.

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Comment by Louis W. Ott on June 14, 2013 at 3:33pm

Hi Dave,

I have a 2700cc Corvair powered 601XL B. I have a bit over 60 hrs on it now and I have the Warp Drive prop I bought from WW. I think it is 68" in diameter. I started at about 8 deg pitch and had around 2900 - 3000 static rpm. Take off and climb was good. Better than I expected. Cruise wasn't so great because the RPM was too high. I think top speed was about 118 mph TAS at 3300 RPM. I then changed pitch to 10 degrees. Take off was acceptable and climb was around 500 - 700 fpm at near sea level at maybe 2800 rpm. Higher altitude operation wasn't acceptable with take off and climb not enough at airports with density altitude around 5000'. I settled on 8.7 deg pitch which works out ok at near sea level and at higher altitude airports too. Full power TAS is around 128mph at 2000' and still 3300 rpm. Cruise is around 115 TAS at 7000' and 3000 RPM and WOT. I use full power almost all the time take off, climb, and cruise if cruise is above 7000'. In the traffic pattern at my home airport at 240' MSL, I use full power for takeoff and initial climb (75 mph) to about 700' AGL, then throttle back to 25" MP and continue climbing to TPA at 1000' AGL. Then throttle back further to 20" MP and about 90mph IAS, until I am abeam the threshold. Then back to 18" and slow to 80, then back to 15" and 75 mph and extend flaps as necessary. When landing is assured, I throttle back to idle. I find it easier to use manifold pressure rather than RPM for partial power requirements in let down and traffic pattern.

My opinion is that the 2700cc Corvair is rather underpowered in the 601XL for any use where density altitude is going to be above 5000'. Otherwise, I love the engine and will stick with it, but with bigger bore and/or longer stroke. You'll save weight too with the larger bore.

You might want to check your ignition timing to be sure that is correct if you still think you are lacking a great deal of power.

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