almost free horsepower!!

Yesterday, the guy that does dynamic balancing of your engine/prop combo came down from Billings, Mt. for an airshow here in Sheridan. It was a good opportunity for me to finally do that balancing thing that I had always wanted to do but never seemed to get the opportunity. After all was said and done the engine was really, really smooth at all rpm's but the amazing thing was that I gained 50 rpm! He said he has seen this a number of times in 4 cylinder lycos. Don't know what that translates to in horsepower but its gotta be something. I gained it all the way from static to cruise.
One other thing for you guys that have been putting it off. My engine, when he started was .5inches/second out of balance. I guess that is in the upper range and I thought mine was rather smooth. When he finished, it was below .1 inches/sec. He said (and this could be just sales talk) that anything over that and the oil loses its ability to provide a film between the front crank and front main bearing. He said this should really make a difference in the longevity of the engine.

Dave Mader
2nd rv6 75 hrs.
Sheridan, Wy
ngSheridan, Wy

Cost? how much

I waited, but no one asked so I am curious, what does this cost?

Jeff H.
Austin TX

lsu-rv said:

I waited, but no one asked so I am curious, what does this cost?

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Depending on who does it/where, between $100 and $250.

free horsepower

Many benefits can be gained from dynamically balancing a prop. As noted an increase in HP, substantial gain in engine reliability, less crew fatigue and the list goes on. The maximum vibration level should not exceed .2 IPS (inches per second), with modern balancing equipment there should be no reason why levels can't be brought below .07 IPS.

As far as cost goes I think the average would be about $150.


Brett

He was giving an "airshow special" and it was $100. I was waiting for an engine/math guru to tell me how 50 rpm translates into horsepower......anybody?

RPM Vs. HP

It's about a linear relationship until the engine can't breathe any faster I believe (where the HP/RPM curve starts to bend over the top).

who to call

Any suggestions to get prop balanced in Central texas or closest suggestion? (since it is an rv, I will travel!!)

jeff h
austin tx

Indeed, there are many benefits to having your prop dynamically balanced. Be advised though that the newest generation of computerized balancers do a far better job than the old Chawick-Helmuth equipment. Our EAA Chapter has purchased a $6,000 MicroVib II setup and we've done over forty member's props so far. More info on our chapter web site...

http://www.eaa105.org/Programs/programs.htm#PropBalancing

Check our "Results" page compared to the this table...
The standard we use is .02 IPS and we've made it in 99% of the cases. This is a great program since we only charge members $20 for supplies/reserves. Other chapters might want to consider it.

Hey Randy,

When you guys do the balancing, do you used the holes in the ring gear plate to mount weights? I tried it, because I saw an A&P do it that way, and it worked great. Nothing like having built in mounting holes for the weights (bolts/washers/nuts) every 30 degrees.

Cheers,
Rusty (finally departing Cleveland after 4.5 weeks)

wyoflyer said:

He was giving an "airshow special" and it was $100. I was waiting for an engine/math guru to tell me how 50 rpm translates into horsepower......anybody?

Click to expand...

Dave,
Since torque is probably pretty flat over the 50 rpm change, horsepower will vary by the same percentage as the change in rpm. For example: If the rpm gain was from 2500 rpm and now is 2550 rpm, the horsepower change would be (2550-2500)/2500 or 2 percent in this case.

-mike