GeraldRosebery

My Feedback: (14)

I am about to install a CH ignition on a brand new Zenoah G26. This involves removing the flywheel which weighs over 1/2 lb. My question is general in nature and I am asking for input from those who have done this sort of thing, not just on a G26. Do the engines run rougher after conversion due to the removal of the flywheel effect that tends to smooth the engine out and improve idle? I know it is not a problem, I am just curious as to whether the effect is noticeable.

Thanks.

karolh

Though I've never had a conversion done to any of my engines, the weight of the flywheel is required in a magneto system to provide momentum to generate ignition current.

Changing to electronic ignition, makes for a lighter, easier starting, smoother and more effecient running engine.

Flypaper 2

Actually the run smoother at idle because with the mag ign. they idle at full spark advance. With batt. ign the spark is around 5 degrees advance, as opposed to around 28 deg. A composite prop will help both run a little smoother as you say, because of the F.W. affect.

GeraldRosebery

My Feedback: (14)

What you are saying then is that the retarded ignition timing has more of a smoothing effect at low rpm than the benefit to be gained from having the flywheel?

Flypaper 2

Yes. Quite a big difference. Very much easier on the airframe.

Flypaper 2

Another thought. They also idle reliably at 1200 rpm as opposed to 1800 to 2000 on mag ign.

WilsonFlyer

My Feedback: (13)

Yes. As a matter of fact, that's one of the major reasons many of us do the conversions to begin with. Timing based on RPMs smooths out the running of the engine at ALL speeds as opposed to being locked into one set timing.

As far as the weight of the magneto helping balance the engine, let me expand on something mentioned above. The magneto is so big and bulky because magnets (used to trigger the spark) must be made of steel (obviously I guess). The excess aluminum is a necessary evil to balance out the weight of the steel magnet. In the end, the big magneto is just excess weight and real-world load that the engine is forced to deal with in order to run that brings nothing to the table for you, per se. That's why you see top-end RPM increases (among other technical reasons too) when electronic ignitions are used to replace magneto systems.

Lose it. Get an electronic ignition and be MUCH happier with your gas engine. (Flame suit on for this one) I really don't understand why anybody in this hobby would run a magneto system at all unless there simply wasn't a complete conversion for that particular engine. Some of the early Quadras come to mind. Unfortunately for me, I have one of them.

Hobbsy

My Feedback: (102)

The prop being much greater in diameter is the real flywheel. I did this to my G45 and it is markedly smoother. I take it that you're putting the Quick Mount on it.

Tired Old Man

My Feedback: (1)

FYI, A true magnet is made from iron. Not to nit pick, just clarify.

Boss248

I have a question that comes to mind when getting rid of the flywheel, can the engine now run on glow fuel? I remember some time ago there were a lot of engines that started out life on gas but there was a sizable increase in power when converted to glow. Is it because of the cost of the glow fuel that I don't see that much anymore or are there other down sides to it?

Boss

Antique

My Feedback: (4)

16 years of testing with Zenoah conversions shows NO increase in rpm..If the spark is in the right place with the mag a conversion won't change anything except the weight...Running glow fuel shows 600 more rpm and much less weight..A glow converted G23 weighs 2 lbs, rpm is 8000 with a Mejzlik 18-6........
Yes, glow fuel at $15 and gas at $2 is a big reason to run a gasser...

Volfy

My Feedback: (23)

Bear in mind that not all electronic ignition systems have automatic spark timing advance. Tthere are systems that are fixed timing. In fact, most weedie conversions are low CR enough to run reasonably well on fixed timing.

Boss248

RCIGN1...maybe I am reading your post wrong but at first you say there is "NO" rpm increase in a glow conversation then in the last sentence you say there is a 600 rom increase and a G26 turning an 18/6 @8000...that's more than a G38 on gas.
I must have missed something...anyway...can you help me find a carb for a 3.5 BME(real old) or a carb for a G62.

Antique

My Feedback: (4)

All tests with a Mejzlik 18-6...What I meant to say was a conversion makes no performance difference over a stock mag using gasoline....
A G26 with a conversion runs the same using gas, picks up 600 when running glow fuel ..You need a WT499 carb to do this....But if you run glow fuel you don't need the weight of the ignition system and battery...
G26 stock or converted using gas, 9000 rpm..I just converted 9 of these, all ran the same...I used a Dale Abell muffler, the stock muffler runs about 8200....
G26 glow, 9600 rpm, glow plug or ignition conversion, didn't try it with the stock mag...
G26 with a Mac's Products tuned pipe, 10,000 rpm gas, didn't try it with glow fuel, maybe later..
G23 stock, gas, 7200 rpm
G23 glow, 8000 rpm..
Most G38s run a 20-8 or 18-10, a G26 won't work very well with one of those.

A prop with an 8 pitch will not reach anywhere near the rpm of a 6 pitch on these engines..
I haven't tried other Zenoah engines using glow fuel.....Imagine running glow fuel in a G62 at $15 for a gallon....
A G62 HDA 48 carb is about $65 retail..A WT76 should work the same, cost about $42.00..The HDA 48 has the pulse hole offset in the base, so a WT76 would need to have the pulse hole relocated or if it's on one of my conversions a fitting in the back cover to connect the pulse hose would work....

Volfy

My Feedback: (23)

About engines running smoother with the heavy magneto flywheel, well... yes and maybe. Yes it does smooth out power delivery in the sense that the added angular momentum does smooth out the power pulses of these singles. This may be more evident in a road vehicle, where the driver may feel the propulsion produced directly by the crankshaft. In an airplane application, however, the thrust is generated indirectly through the propeller, so I doubt the effect is felt at all.

The other facet of smoothness is in regards to the vibration generated by the inherent imbalance of the single cyl engine. Though some have claimed an external flywheel purposely off-balance to counteract single cyl's primary imbalance can actually reduce the "felt" vibration, I have yet to see a convincing case of it. It might improve things at some RPM ranges, but it cannot possibly smooth these thumpers out overall.

Most of the smoothness gained with the electronic ignition conversion is because of the automatic timing advance.

Antique

My Feedback: (4)

A heavy engine will feel smoother because the extra weight soaks up some of the vibration..
The Precision Eagle 4.2 engines felt pretty smooth, but they weighed about 6 lbs..There was no attempt made to balance the crank..I have seen the insides of enough of them to know....[8D]