Here's a new option in our Gas/Glow endeavors; a Super Tiger .90. It is being offered converted for gasoline use by Keith at BME engines. However, I decided to run mine on Gas/Glow.

It runs great!! However, it comes supplied with a ZAMA carb that I had troubles with regarding the Gas/Glow fuel. The engine ran excellently at first, but after a day or two exposed to the Gas/Glow fuel, I started having problems. I tore down the carb and found the fuel pump diaphragm severely distorted. I tried another diaphragm with the same results. These were clear plastic diaphragms. Keith says he has run ZAMA carbs on glow fuel without problems in the past, but perhaps there has been a change in the diaphragm material.

Anyway, it took a touch of grinding here and there but I put a Walbro carb on it, (the Walbro is physically larger than the ZAMA), and now after several days and many runs, no more problems and it runs really great! Nice slow idle, easy starting and handling. It turns an APC 13 x 6 at over 11,600 rpms.

I've not had any problems with the Gas/Glow mix on any of the different types of diaphragms that come with the Walbros, but watch out for those ZAMA carbs when using this system.

I'm really pleased with the BME Super Tiger .90 though, and recommend it!
Here's some pics...

As an interesting side note, even though this engine is only 15cc, it comes with an 11mm venturi. No problems with transition, etc. nor any other signs of being "over-carbureted". It handles like a *****cat.

AV8TOR

I can't believe the system bleeped out "p u s s y cat"... []

AV8TOR

Besides the carb, what changes were made?

I didn't take it apart to check, but I believe he puts roller bearings on the con rod wrist pin and crank pin, makes the adapter for the carb, etc.

Sure handles nicely. It's got me thinking about a 2300 or 3250 Super Tiger on Gas/Glow.

Keith might see this and jump in here...

AV8TOR

I have found only two engines that were not amenaable to operation on glow/gas fuel. Sometime back I discussed the problems I was having with a Stihl 35 cc and a Shindawa 23 cc. Both of these engines had an "effective compression ratio of better than 13/1. I tried several fuel mixes to get the highest octane possible that would still run without constant battery power on the glow plug and in addition several different glow plugs with heat ranges from cold to hot. I was never able to get either of these engines to run without significant vibration in the 4000-5500 rpm range. These problems all pointed to signification ignition advance in this rpm range. I am flying both engines currently, but am operating them on EI syncrospark. Operating in this manner both engines are well behaved and mid-range vibration is minimal.

The reason I mention these two engines is that they both have significantly higher "effective compression ratio" than other engines that I have operating of glow/gas. The engines that I have operating on glow/gas are: Homelite 25cc, Mac 28cc, Mac32 cc, Echo 38cc and a Zenoah 40cc. All are well behaved and quite powerful, but all have an effective compression ratio of less than 10/1.

In retrospect, I wonder how those higher compression engines would have worked out with a higher percentage of the glow fuel in the mix? Maybe 50/50?? The increased effective octane of more methanol might have helped. (Yes, that would have made the oil content richer as well...) Just a thought in passing...

AV8TOR

After some consternation over how much combustion chamber volume I should put into the glow head I was making and making a pest of myself by being lazy, I went back to the beginning and started reading. Three hours later, (its 2 AM here) and only at page 15, I started to skip ahead. At page 39, I found much appreciated info from Ringwinger and others. Thanks guys, it was all there.

Then I come here to post my thanks and MORE good info. Thanks Will and AV8tor.

Pictured is the result. Using EFFECTIVE CR, I've done it up a shade overcompressed at 13:1. I was concerned over losing the benefits of squish band but it appears that it's not that important. So, I'm overcompressed to start but I won't start there. I've made up multiple shims of aluminum in various thicknesses and will use them to affect a much undercompressed condition. Based on all the good info on this thread as to what to expect, I'll be running the engine on various fuel mixes, glow lit, not lit and varying the compression ratio to see what we can learn. I'll pass on anything I come across of interest. I suspect though, that I'll just be confirming much of the great research that's already been done.

Many thanks to all,,, hey it's been over three years.

But Global Warming has become a fickle mistress. Two days ago, we had zero snow on the ground with temps in the mid 60s. Yesterday, we got dumped on to the tune of 18 inches and temps are 10 below with wind chill down to 20 below. Not gonna run this engine again for a while it seems.

AV8TOR,

One of the runs was on stright methanol 2% oil and no nitro. Another run was 50/50 methanol/gasoline 2% oil and no nitro. The only mix that came close to being acceptable was 25% methanol, 25% gasoline, 25% ethanol, 23% toluene and 2% oil. If I remember, and calculated correctly, that mix should have had an octane rating of about 118. I could have used this mix, but the cost of the ethanol and toluene made it come out near the cost of glow fuel, so why bother.

Hey guys I got a 30cc homie from a garage sale brand new for $20.never was started.bad news is when I was working on it I pushed the piston up to far in the head and when I tride to pull it out it was stuck,you know what happend then,busted the top out trying to get it out.well new piston .I do have all the porting ,chain saw carb,and block done nitro/gas .I should have known but all I have had was 25 cc without the top ring.Good news is my sig 1/4 piper cub is almost done windows and covering the landing gear and mounting the tank down.Just in case the lawn shop dosnt want to sell a piston,where is a good online shop?

Hey Varn!!!
the testing you have just described was performed with a glow plug or EI?
We ranned the glow/gas fuel (1/3 glow fuel, 2/3 91octane gasoline) on a ryobi 31CC and it increased about 500 rpm's compared to just gasoline and oil at 40:1 ratio, I know for a fact that the addition of methanol increases octanage but then you have the 2-3% nitro on this fuel which would help improve performance: what's your opinion?

Check your local repair shop's scrap pile, you should beable to come up with a free bee.

Aero Nut,

The testing was on glow plug. I had intended to use one of these engines on a plane which would have a lot of electronics and I didn't want any potential interference from an ignition. Both the Shindawa and the Stihl produced great power on the gas/glow, but had extremely bad vibration in the 4000 to 5000 range. After a lot of reasearch and comments from others that have been posting on this thread, I came to the conclusion that the problem was ignition timing due to very high compression ratio. The mixes I used were intended to increase the octane rating of the fuel to offset the ignition problem. I finally setteled on a Homie 25cc on gas/glow and it works great.. The other engines did not have the mid range vibration when run on EI with syncrospark. I am using the Stihl on a H9 Ultra Stick and the performance is great on EI.

Would it be possible to gut the sparkplug cavity, gas braze the void with bronze rod, drill and tap for the glow plug?

Horizon Hobbies has glow adaptes for about $7.00.

They are listed in the Zenoah parts list.

Yes it is possible to make your own.

Dad and I used to rebuild antique engines. We put a grease zerk in the plug hole and pushed them out. Works good, gives even preasure and a lot of it. Put if the ports are exposed then you have to do something else.

Did any one ever get a Stihl to run good?
And theres been a few test with a weedy 18...what kind of results?

Any idea where I could find one of those s 2000 needle valves. Now for a stupid question. Can you run nitro fuel thru a walbro?

this thing finally die?

Thread seems to have slowed down, but I presently have 5 airplanes flying with the Gas/Glow system. Everything from the Super Tiger .90 conversion up to a 42cc Poulan. I'm working on a 48cc twin that will also be Gas/Glow.

TWIST 60 3D -- Super Tiger .90
FOKKER TRIPLANE -- Echo 23.6cc
KATANA 140 -- Echo 23.6cc
78" TIGER MOTH BIPLANE -- Ryobi 31cc
GIANT BIG STIK -- Poulan 42cc

All on Gas/Glow....


AV8TOR

Hi Bob
How is the supertigre 90 runs with the gas/glow configuration???
I'm thimking on running my Magnum 1.80 on this fuel but with at least 6-8% oil, what do youy think??
Aero Nut.

How much vertical does the Kantana 140 have? Thanks Capt,n

Maybe not. I've got a converted Tanaka that does 7,500 on a Zinger, 18 X 6. This one has a reed assembly attached to the bottom of the case instead of piston induction. Works real well at full bore but dies at anything under 3/4 throttle. Plus, it's using a standard RC throttle carb. On just methanol and 30:1 Klotz Benol, and on a mix of 50/50 gas/methanol, it runs strong and smooth with the edge going to the gas mix. I added nitro and it didn't like it becasue I'm running 14/1 compression ratio, rather than the usual 7/1. Adding a couple of headgaskets helped. The interesting thin is, that when I deliberately overcompressed it with some alterations to the original head, the result was a no start, even with an electric starter. I had to add shims to the modified head and bring the CR back to where it was on the original run.

Once I get some of this sorted out, I'll try some straight gas/oil mix and play with compression to see if we can eliminate the glow igniter altogether. This has likely already been covered but maybe with higher compression, we might get ignition purely from the glowing element and not really needing the catalyctic action.

Anyway, here's that run. http://www.youtube.com/watch?v=noH_SOBe0YE

Whoa, a 48cc twin? Please elaborate.

Please, no. I don't have time lately to play with my engines as I'm on the road almost every week, but I hope this crazy time will end soon. I have Seagul Harrier 90 still in the box waiting for gas/glow Poulan 25. As soon as I make it happen I will report.

Hey RIZ....it is good to hear from you..."YA TURKEY" I hope life is treating you good. Take Care Capt,n