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Hartzell v. 74RV
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 |
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 |
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 |
200 HP +
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. |
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