I would suggest all will be roughly the same.In my mind the different engine/cylinder designs have to change effieiency. I want as much speed as I can get with efficiency. Since I am not changing airframe, my engine is the only variable. Lets say all engines can achieve 175 knot in my frame, will one engine type IO360,IO375,IO390 do it for less fuel burn. If the answer is no they will all be the same then it is just a matter of how big I want to go.
Thanks guys. After Your help and 10 hours reading old threads, the cost of a certain speed is the same for all engines. If I have a larger engine I can throttle back and it will cost the same per mile as a smaller engine. A smaller engine cant go faster. I can see a IO-390 on its way
Thankyou all
Ben
Saw it in a post from somone With a red 8 with checker rudder and flaps. It got hit at fun n sun
Can someone please give me bare figures on IO-360 IO-375 IO-390.Fuel burn verses IAS in a RV8 at 75% power