912 performance question

[Morph]

I think I have the 2.273 ratio gearbox in my 912UL motor. I have been told it is better to have the 2.43 ratio box.

I have been told that the 2.273 ratio runs rough between 4300 to 4800 rpm with the roughest patch being at 4500. which is the rpm that most guys want to cruise at. I have also been told by Pieter De Necker that the 2.43 ratio will swing a fatter prop giving more thrust.

Now apart from this what performance difference should I expect between the two ratios. Obviously I can see the prop will spin faster per rpm on the 2.27. A faster spinning prop in my mind equates to a better climb performance but not cruise

Who of you is experienced on the 912 80HP motor and the two ratios?

[Boet]

Yes the 2.43:1 ratio is the better one. Try it first with the 2.27. It SHOULD be OK with the 3-blade Ivo-prop. It is hellishly expensive to change gears.....
The 2-blade props is very rough on certain ref ranges. True. I have not noticed this on 2-bladers. Get the aerie finished so we can begin test flying!! :D :D

[Morph]

I've taken your advise, this is not a big job, it's a sh!tload of small jobs

See you in the air soon