Balance tube size

Hi Rusty,

The results aren’t science based or confirmed by instruments able to show an improvement. They’re all just based on supposition from running the engine. I’d like to see real instrument and science proved results. Maybe a cheap and dirty way is to use a Chadwick or Ace prop balancer on the engine and just record the vibration level. Then install your 1” tube and then run it again and see if the vibration changed.

Just a thought

Hi Rusty,

Purely speculation;

I would doubt there is a downside, except to your pocket and a miniscule weight increase.

As for up side; cant see one. The inlet air/fuel column "pulses" are caused by the piston/inlet valve action, are inherent in all piston engines and will not be overcome by a change in balance tube dimension. More cylinders, turbo or super charging and a single inlet manifold, may result in a smoothing (to some degree) but it is always there.

"It's pretty hard to believe that all the reports I've ready were just from wishful thinkers"

You have heard of Fashion? Trend? Movement? - just because a group of humans do the same/similar thing, may have little to do with fact /logic.

I agree that users impressions of mods aren't the most scientific.  I'd love to see some instrumented testing of various size balance tubes, but for now, user impressions are all we have.    

Rusty

I would also agree with Sean that there doesn't appear to be any downside except cost, time, some weight, and possibly loss of warranty. If it makes you fly happier in your mind then go for it. Only one caution in my mind is that if you do major welding on the inlet manifolds, make sure you check and correct any loss of flatness on the manifold to cyl head surfaces due to possible warpage from welding.

It just isn’t necessary. I would like to think that Rotax over the years has tested things like this. May someone from Rotax here will respond.