Worth changing prop from 64 to 66 for cruise speed boost?

[N754TA]

So I purchased my model A sonex with a 3300 Camit this past winter. Currently I only have 22 hours on it. Going to do some upgrades this spring come annual, Rotec TBI being the major one.I really bought this as a cross country machine and would like to do whatever I can to bump up cruise speeds.

Currently the prop is a Sensenich W54SK-64G that was originally mated to the jabiru 3300 the plane was built with. But the builder swapped out the engine for the Camit 3300 about 179 hours ago. Current Prop: 735 TT, 285 since overhaul at factory.

On the Sonex website they recomend the 64 for the Jabiru 3300, but the 66 for the Camit 3300 which I find really strange...

NOTE: I am not married to Sensenich, so any other recomendations for a cruise prop would be appreciated! Maybe an IVO ground adjustable? I had one of those on a Kitfox 3 I owned previously.

[DCASonex]

The Jabirus with their hydraulic lifters were not putting out their rated 120 HP. My CAMit (solid lifters) was dyno tested before shipment at 127 HP. Retrofitting Kevin's forged pistons with improved "Squish area" seems to have boosted output by about 10% which would mean it is now producing about 140 HP. I am flying as a sport pilot and maximum cruise speed to remain LSA legal is determined by that 64" prop turning at 2,850 RPM If the expected increase in LSA cruise speeds passes, I intend to go with a steeper pitch perhaps from 64" to 68".

David A.

[N754TA]

Dave,

Yeah so whats weird is if you look on the Sonex website they recomend the W54SK-64G for the Jabiru 3300, but the 66G for our Camit 3300. Pretty strange... I emailed them about it but they are on break till after Labor Day so I will have to wait for an explanation.

I am learning towards the idea of an IVO ground adjustable prop so that I can tweak it to my fancy. I had one of those on a Kitfox 3 I used to own. I emailed them with my application and waiitng to hear back currently.

[Skippydiesel]

Ground adjustable is the way to go - this way you can "tweak" the prop for your particular preference/mission.

"....I intend to go with a steeper pitch perhaps from 64" to 68"."

Out of curiosity - since when was prop pitch measured in inches??

[Bryan Cotton]

Out of curiosity - since when was prop pitch measured in inches??

Probably a hundred years ago or so. It's the theoretical distance the prop would move forward if there was no slip, like if it was a screw going into metal.

[N754TA]

Ground adjustable is the way to go - this way you can "tweak" the prop for your particular preference/mission.

I am starting to think along the same lines. IVOPROP ground adjustable comes to mind first, but that’s only because I have one on a Kitfox 3 with an 80hp 912 I owned previously. I emailed them yesterday asking about one of their products for my Sonex/camit 3300 combo. Waiting to hear back.

[Skippydiesel]

Bolly - Australian brand, has extensive experience with Jab/Camit engines. https://bollyaviation.com.au/oem/
Then there is the French maker EProp, thats getting a lot of press. https://www.e-props.fr/

[DCASonex]

Just make sure the new prop's moment of inertia is less than the max specified in Jabiru's manual be it a Jabiru or CAMit engine. There are posting on this forum on how to measure the moment of inertia for unknown props.

David A.