Hi all,

Any idea what size prop this puppy likes and what the max RPM should be? This pic is before the pickup sensor was mounted. I mounted a larger bore carb on it, as this pic does not show the carb on it yet. Got it in a H9 Super Cub.

these are designed to spin! don't overprop it. 15x8 or 16x6 are good and should give about 8,000 rpm. haven't tried it yet but a smaller prop might even be better. in the echo manual it states that the engine should turn between 9-11K in its original application.

go to the "engine conversions" sub-forum and you'll find many threads about this engine like "don't forget echo!" and "echo on a funtana" lots of info and hop-ups.


dave

Thanks Dave, thats exactly what I was thinking, 7-8k. I'm running a 16X8 but its only pulling 5900 thought that was a tad low, Sucker idles down to 1400 with no problem although I don't think I'll let it dip under 2k for flight. I'll check the links, thanks!

FWIW: On 21 Echo just converted CH IGN w/ WA167 carb (11.11mm) APC 16-6 1600 to 6850; Zinger 16-6 the same. It will idle smoothly over 5 minutes and transition nicely. 1.085 Kg.

One observation I can get max rpm at 55% of throttle opening, all additional throttle does is let the carb start blowing fuel back out of the intake. and noticeably more unburned fuel out exhaust deflector. Any thoughts on carb sizing and prop size?

AC2 Have you tried any 15 inch props yet? Results?

I just started running my Echo 21 again. I tached it at 6500 with a 16 x 8 mounted. Static thrust was 8#. My tach started acting up so I did not get a good reading (didn't sound faster) on the 15 x 8, but the thrust was down to 7# and the flight performance was measurably down. I am interested in performance mods so I will check out the referenced threads. A couple of years ago I had about 15 to 20 thou shaved off the cylinder body to increase compression ... seemed to help, but no hard data.

Ain't gassers fun!

Bedford

mikenlapaz, sorry for long delay in answer, been working tons of overtime....
To answer your question I have not yet tried any other props.........

Where are you guys getting your prop hubs from? Are you making your own? I have a P-61 twin fighter bomber project that I would like to use a couple of these little gassers. I would like to get the FPE wrap-around mufflers to fit in the tight cowls better. Thanks.

Shouldn't this topic be more appropriate in the Conversion forum?

Made locally and p washer on drill press. http://www.rcuniverse.com/forum/thum...93/Gb90168.jpg