fastball48

Hello all, I have a Zenoah G-38 on my CG 77' Edge 540. I flew it for the first time just a couple days ago. I understand that this isn't the ideal engine for the plane, and it is a little underpowerd for my taste, but being dumb i found that out after the fact that i had already installed the engine in the plane so oh well, nothing i can really do there. My question is that for some reason the engine is perfect up until about 70% power. Then from 70% to 100% throttle i hear and see basically no change in the engines power while flying or on the ground... anyone know what could be causing this?? Its been tuned by me and fellow club members and when i look in the carb at full throttle the butterfly is completely open. Any suggestions??? Thanks

ROGER RUSSELL

My Feedback: (12)

This could actually be in your radio/throttle linkage set up.

While looking at the butterfly, move your throttle up/down so you can see the movemennt, you may be reaching full throttle at 70% of stick movement.

You may need to adjust your throw/our adjust end point travel if you have a computer radio.

Just my thoughts.

Aslo, out a tach on it to see what your top RPM's are.

jack1933

My Feedback: (2)

I don't think you will see a lot more power from 70% on, just my experence.

joseph.batson

I have the goldberg extra 330 w/ the G38, just a couple weeks ago I was having an issue similar to yours. It would run fine but acted like from 3/4 to full thottle nothing was happening. Ended up being the spark plug, added new plug and fixed the problem. I will be converting my G38 to electronic ignition to loose some weight on the front end, should help tremendously.

fastball48

I might have to try getting a new spark plug then and seeing if that helps, i'm also gonna be switching to an electric ignition. How is your vertical currently with your plane??? Mine seemed sort of sluggish.

arobatx

This isn't anything specific to the G38...I think you'll find with most of our gas engines that little increase in power/rpm is noteable toward the end of the butterfly rotation. This is why folks dial in a throttle curve to make it feel linear, or to tune the feel to their preference and/or flying style. If your engine/muffler/prop combo is taching in an acceptable range, take your peak RPM on the ground, split it in half, set your throttle stick to half position on the TX, and ajust your throttle curve to match 1/2xfullrpm. Then from idle to full it will feel and respond in a more linear fashion. Its a good starting point from which to fine tune the feel as you progress and get used to your plane/engine.

...if you really want to play, some engines will respond with a little extra RPM by rotating the throttle butterfly slightly past full open, or slightly prior to full open. There are some engine/carb combinations that respond very little at anything over 1/2 open....

Chad

tkg

My Feedback: (1)

Your prop is to big, put a smaller one on it and let it rev up. Then the throttle will work better.
With a too large prop, a slow turning engine it only needs so much air. Once the carb passes the required airflow for the rpm its running at, then opening ithe throttle futher does very little.

rc bugman

My Feedback: (30)

I agree with TKG. Reduce the prop load and let the engine rev.

Elson

jack1933

My Feedback: (2)

I just said that

captinjohn

REPLY What prop do you have on it now and what is the all up weight ? Try a lower pitch prop. Capt,n

hutchi

Well guys I just flew my 73" edge540 with a converted to EI G-38 using a 18x6 PRO Zinger an it sucks for power or speed , looking for suggestion on what way to go with prop. longer more pitch, shoter more pitch ect.......... thanks hutchi

Whistling Death

Hmm, I have an EI G-38 on my H9 P-47 150 and it hauls a##. I have an APC 18X6 and it slings that 80" warbird around pretty good.

captinjohn

Somebody said on here....if you want a lot of noise and not much performace...use a Zinger!!!

hutchi

ok so what are you saying

arobatx

What top end RPM are you getting on the ground? Have you tuned the engine for peak performance? Zingers are in general not known for being efficient nor performance propellers. There are other alternative wood props that will offer much better performance. My favorite in wood is the NX lately, really great performance from an inexpensive wood prop.

hutchi

Thanks arobatx I just got this back from RC Ignitions with the conversion there is only about 1 gal thru it so I'm still running a little rich an I did not tack Iwill tomorrow, It just seemed so slugish I wright away thought wrong prop,

mrbigg

My Feedback: (21)

I really need to build a test stand, header, and start playing with a tuned pipe on my 38..........

arobatx

Mrbigg, do it man! I never hear about anyone playing with a pipe on a Z38. I've always wondered though. The 26 with decent in cowl muffler and good carbon prop...compared to the 38, similarly equipped, make about the same thrust. The 26 on a pipe with the same carbon prop starts to get insane, not unlike the G62 when you start playing with headers and pipes. The 38's rear exhaust would make for a nice straight header/pipe install....hmmmm, definitely let us know, or shoot me a PM if you start playing with this.

Chad

joseph.batson

I use a ProZinger 18x10 and it spins up nicely, vertical is good, but probably couldn't hover the plane. I think one of the new Evolution 19x8 props might just be better.

karolh

A Xoar 18x8 should work quite nicely here, just remember that engine /model /prop combinations can perform quite differently for each install.

Karol

captinjohn

How many places handle the 18X8 Xoar propeller? Thanks Capt,n

mrbigg

My Feedback: (21)

I'll let you know. That would be a good combo on an OMP 80" Edge profile.

karolh

Graves RC Hobbies, Chief's Aircraft and Abell RC has that size listed in their on line catalogue.

Karol

hutchi

I've order a 18x8 xoar will see how that goes I did try a 18x8 APC an was a litter better than the zinger. then I was going to try an lean out a bit for peak performance an notice my high speed needle was completely closed I tried to call ralph since this just came back from him but he is out of town till the 25 so I have no clue how this motor is running this good