Hi Somebody
i did bought a new os 46ax engine for my 40-50level plane. i like speed fly.
but all the friends here said i am stupid, why not but OS55 ax engine .
my opinion is 55ax may be will over temperature(too hot) and the stroke is longer than 46ax, so i think 46ax is much better for speed.
not i am very confuse, which one is better for speed fly, my fight is always 40-50lever. it means 2200-2600g weight.
thank you for answer

nobody can advise me?
somebody help me .please.

What airplane are you flying? The short answer is yes, the 55 will put out more power than your 46. Is your 46 worthless? No. It's a great engine and more than likely will power your airplane with aplomb. Want more power than is necessary? Get a 55.

Another consideration is prop size. Will the gear tolerate the props you are likely to use on the 55? Is fuel tank size an issue, the 55 does sip a bit more.

For a 2.6kg plane, I would have thought that the 46 is ideal. The 55 is definetly more powerful, but it might not translate into more speed on the plane. Depending on the plane (high wing, low wing, wing surface area), it is likely that the 46 is already maximum speed for the airframe. Using a 55 can't make the airframe go faster in this circumstances

thanks for answer.i always blast my plane, so i change my plane all the time. some time i fly 40size, some time 50size, so i just worry when i fly a 50size the OS 46 can't provide enough power to fly. and i always like speed fly, as my friends opinion is OS55 can take a bigger size prop. and with the same RPM as OS46, so OS55 will fly more speed than 46.
now i am going to use 10*8 and 9*8 on OS46 for speed fly.

There's not THAT big of a difference between the two that a plane will be unflyable with one and fly well with the other. The 46 with a good tune and and trying a few props would outperform 55 with a random prop and a tune that just runs.

Originally Posted by Ira NZ

There's not THAT big of a difference between the two that a plane will be unflyable with one and fly well with the other. The 46 with a good tune and and trying a few props would outperform 55 with a random prop and a tune that just runs.

I agree, they're pretty similar engines. I think the 55 will outperform the 46 in most configurations, but not by much, and certainly not to a ridiculous degree. A tuned pipe on your 46 would DEFINITELY put it over the 55, however.

thanks all. it look like i bought OS 46 is good. and it can fly 50size airplane well. that's great for me , and i already bought 8*8. 9*8 10*8 11*8 12*8 for this engine to try

You might be better with some lower pitch bigger props, like 12X5 if it's a fairly draggy plane.

Hi Ira NZ
why i always choose high pitch props, because i like speed fly, i prefer the props size smaller but pitch higher.
do you agree?