# Thread: Ring Size and Prop Pitch effects on RPMs

1. ## Ring Size and Prop Pitch effects on RPMs

Which is the best ring size for top speed...it seems 81 mm with the prop pitched for the correct rpm is the norm but does this cost a great deal in acceleration to 'ring down'...?

What does a change in ring size typically net in rpms? 1 mm = (x) rpms

I realize bigger ring equals more rpms and these questions are assuming back to back changes with the same conditions...

On a related subject...what does a mm change in pitch of a prop translate into rpms...with all other factors remaining the same.

2. 1 mm in the prop usually is about 100 rpm's. The rings are about 80 rpm's difference, at least on mine.
Everybody has an opinion on this, but this is my take. Pitch the prop to the perfect RPM with the 82 ring in it when the temps are in the 75-80 degree range. When it gets into the 90's you install 83 ring, when it cools off to the 60's you go 81mm ring. This is the most convenient way, so you are not bending the prop up and down. I have hit my best top speed with a 82mm ring.

3. ## rings

the thing that i have noticed is the diff in the "pull". when you have the 83 or 82 you get better bottom end than with the 81.

most have found there best top speeds with the 81 .....that may be just how it works out but most would agree on this i think.

4. And each of these rings cost about \$40 each...right?

What are the approximate temp/rpm ratios....? 10 degrees = (x) rpms

So I could dial with a 81.5 mm...kit comes with 81, 82, and 83
I could buy 80 and 81.5 to have about 100-125 rpms for 'cold weather 55-60 degrees or so', which is rare in MS and even more rare for me to ride in it, I would then have 82 and 83 for the much more common (constant) heat/humidity!

Ideas and suggestions...?

I wish I could also add the AAT (adjustable shuttles) but it is unknown if it can be ran with the Triple Bearing Pump mod...? Anyone know?

5. Originally Posted by DIGGS
the thing that i have noticed is the diff in the "pull". when you have the 83 or 82 you get better bottom end than with the 81.

.
I agree with this.

6. In my case going from a 83mm nozzle short shuttle{summer time}to a 80mm nozzle longest shuttle in the winter. I really dont think just the nozzles would do it w/o the shuttle kit unless I bent the prop. i usually dont ride long at all in the cold just top speed runs and on the trailer. BRRRRRR!!!! Thank goodness fer de Crown Royal

7. Originally Posted by RXP Steve
Everybody has an opinion on this, but this is my take. Pitch the prop to the perfect RPM with the 82 ring in it when the temps are in the 75-80 degree range. When it gets into the 90's you install 83 ring, when it cools off to the 60's you go 81mm ring. This is the most convenient way, so you are not bending the prop up and down. I have hit my best top speed with a 82mm ring.
I agree I would do the same. Much easier than having to props and pumps.

Originally Posted by DIGGS
the thing that i have noticed is the diff in the "pull". when you have the 83 or 82 you get better bottom end than with the 81.
Yep i wouold always put my stock size 83 ring back in to have the fun factor of the pull when you hit the throttle, but if I needed a little more up top for a speed run I would go 81mm ring. But IMO the 83 was more fun.

.