Is there a link that lists RPM ranges for certain props? I have a APC 12x4 on it right now. Ive been trying to tune it and with my digital tach Im getting about 12700 at full throttle, should I be able to tune it higher?

I would be happy wit that. RPM can depend on the prop, fuel, elevation, weather conditions, etc. You also have to be careful and not get too focused on squeezing maximum RPMs out of the engine. For racing that might make sense but you don't want to over-stress an engine in day to day flying.

I would think that is about right for the prop, if you droped down to a smaller diamater prop you would get higher RPM's

What plane do you have it on?

The guy I am working with has a new Mag. .46 and he is running a 11x6 and getting around 12k rpm. Its no a trainer and we don't want speed, just slow and power.

I get 2100 at low end and 13000 tuned down to 12,400 for high end with my 46AX. You shouldn't need any more RPM than that.

State your prop size else you're post is useless.

I spin a 11x6 prop on my 46and it's 2800 or so at idle and about 12,200 at full open. this is a LOT of power for my 4*40..



Don't make things more complicated than they need to be. Tune by ear or Tach but the method is the same.

open throttle, and start leaning out the engine till it peaks and starts to drop off in rpm. This is a VERY noticeable change and you just can't miss it when it drops rpm, now you want to go back to the peak again and then richen the needle 3-4 clicks from peak.

now let it idle for a while, if it loads up and dies, lean the low speed neddle 1/8th turn and let it idle. now, increase the throttle (after it's been idling) and you should get VERY VERY little to no hiccups. if so, lean out the LSN a little more. Now go back and recheck our High speed needle settings.

I've tuned a few engines at my club (been tuning RC Car engines for a while and you guys in that hobby know ho tricky those can be). OS 46AX is a breeze to tune and it stays that way. I think it's pretty much THE set it and forget it engine.

12x5. Lots of pull, and still lots of speed (everyone says my Dolphin is a rocket!)

Also how new is the engine (how much fuel through it)? Mine, after 7 or 8 gallons this summer is still increasing RPM's. When I put the 12x5 on it sounded bogged down a month a go, now it's up to 12000+ and screaming.

What are you looking for? Power or speed? Smaller pitch numbers give you more RPM and more power, but lower speeds.

But, just remember that noise does not relate to speed nor power. The RPM numbers that show up on spec sheets for various engines are not really useful nor practical. The RPM range you are working with is probably where I would keep it at for good practical flying. If you want more power, go to a bigger engine.

Tune the engine so that it is below peak RPM so that it is slightly rich. If you are not sure how to tune the engine at full throttle, ask. We will be glad to 'walk' you through this.

CGr.

Unless you are trying to point straight up and hang on the prop type of stuff I would suggest that you go down a size to an 11-5. I think you would find the all around performance to be better suited for most other types of flying. [8D]

The OS 46AX along with the 12x4 is the recommended engine and prop for the Pacific Knockabout.

Again.. what are you looking for in performance? The recommended prop size wll give you one optimum RPM range and that's probably within the limits of that engine. Trying to get more out of it will actually give you less performance and more wear and tear on that engine.

Stick with the recommendations and go with the RPM you are getting. That's just fine.

Or, as I said, get a bigger engine. An OS 55 AX has the same footprint.. and will have that thing standing on its tail from the ground to the clouds without difficulty.

CGr.