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Comment by Michel Therrien on October 18, 2016 at 7:23am

Forgot to ansswer your question on performance:

- takeoff RPM is 2350

- seems best climb rate is approx 75 mph, 900 to 1100 fpm at 1200 lbs loading (my gross limit is 1400)

- cruise is : 107-111 at 2400-2500 rpm.  On some days I got more: 115 mph. 

- I made the integrated elevator trim tab shorter than specified in XL plans.  I regret as my tab is too small. 

- stall speed is still around 47mph

I believe that if I use a 55 or a 54 inch pitch prop, I would get the same cruise speed.  However, I would obtain better climb performance.  I would like someone to testify this for the CH601-HD.. I think this plane has so much drag that we face a diminishing point of return quickly with the prop.

For EGT, at 2400 rpm, EGT span is approx 90 degrees.  It will be more at full throttle (150 degrees).  Cruise EGT is between 1320 and 1420.  Interestingly, at 2200 rpm, it goes up and at full throttle, I have two higher and two lower EGTs (higher above 1450 and lower in high 1200s).  It really seems that mixture is not linear.  I added a grill in the carb intake and this helped. (before, results were much worse).

My CHTs are low... I was not able to have them much above 285 yet.  Before making more changes, I wait for my spinner to be back (I returned it as it was not centered).

Comment by Michel Therrien on October 18, 2016 at 6:59am

Hi Joe,

This is not the Sport 4... it is the 4A-235-B31 with the spider manifold below the engine.  I will try posting pictures of my exhaust system.   Which prop do you use?  I use the W68ZK57 and I feel it is too coarse for this CH601-HD aircraft. 

Comment by joseph aloof on October 16, 2016 at 7:04pm

hi mike..hows the performance with the engine?  its the sport 4 franklin?    are you monitoring the cht   egt?? what prop are you running,i also have the franklin 115 hp with a wood prop still getting things together,,,your exhuast do you have any pics   my exhaust are j pipes straight out   very very loud thx    joe

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