whirlwind 74RV in taildragger?

[RV7ator]

I changed from a 72" Hartzell BA to a 74RV at 75 hours on a IO-375 mounted on a -7. I was concerned about vibration effects on an aluminum club from a ~210hp engine with EI, 9.6:1 compression. What performance comparisons I made did not show detectable, repeatable results between the two. My butt tells me the 74RV is a bit smoother. Prop looks a lot faster than what you'll experience. Don't sweat the inch radius on a TD unless you try to "pin" a botched wheelie. I know a guy who trimmed a BA from 72 to 70 doing this.

John Siebold

[DAS]

thx all,

John, is there any sig problem with the 210 hp in the RV7? I was looking at superior's engine, similar hp....obviously vans "can't endorse that HP, but you're the builder, so you can decide" was their answer..

das

[RV7ator]

More horsepower = better. Too much horsepower = best. You can always pull back the black knob.

Now let's see where this thread drifts.

John Siebold

[RV7Guy]

I had a 200RV on the 7 that I sold and it was great. Smooth and reliable. The new 7 will have a new IO390 with Barrett Precision work done. It is close to 220 HP.

I consulted with Whirlwind and they said the 74 is most efficient with 200+ HP engines. Below that the 200RV is more effective. The 74 has more diameter and a thinner blade.

So, 200 or less go with the 200RV, 200+ consider the 74.