liquid TR, were you able to try the evo carb Sunday??

I tried the whole system today - with HUGE success! YAY!





Here is the tuned pipe data:

Fuel: 95 Octane gasoline with 10% mineral oil. (castrol Scooter 2T)
RCexl Ignition: 1 cell 1500mAh LiPo
Propeller: JXF Wood 18x8W
Tuned Pipe: MVVS 26CC original
Header: Just Engines Custom Manifold
Carb: Walbro Evo 26CC original (9.53mm throat)

With original length header:
7500 RPM MAX
1900 RPM IDLE

With 1 inch chopped off of header:
7800 RPM MAX
1850 RPM IDLE

With 1 cm more chopped off:
7920 RPM MAX
1800 RPM IDLE

With 1 cm more chopped off:
8040 RPM MAX
1750 RPM IDLE

Incredible transition. No overheating and very quiet.
Actually I could gain a little more from the engine by cutting the header even more, but this was satisfactory enough for today.

This concludes that OS 160FX is a primary candidate for a gasoline conversion.

That's excellent!

I'm glad to see this too. Would you say using the walbro carb is worth the change or is stock carb good if one can adjust the needles?? Also on first post you are turning 18*6W on gas with more oil than needed 8450rpm with no pipe. 8040 on 18*8W with pipe and less oil so do you feel pipe is more power or pitts muffler about as good. I have 2 of OS160fx on planes and don't want to change exhausts or carb unless necessary(cowl unavailable for one plane). I also have 2 OS120AX and wonder if they would convert as well. I think the conversion would be worth it on engines already installed in planes as a lot of the cost of converting is offset by cost of new gas engineAND cowls,firewall changes etc THANKS,RACJ

In my opinion, any engine can be converted to spark ignition and gasoline. The questions is how much oil is needed, and whether or not the stock carb will be acceptable. I would use a Walbro where space and weight allow it. If the stock carb tune well a Walbro is not needed.

Liquid, I like to see a viscosity of >13cSt at 100°C. I would use a more robust oil, especially with a pipe.

the original glow carb is totally acceptable as it ran very good with it. But this engine is going into a critical airframe for F3A competition. The tank is located at CG so its necessary to have a pump of some sort. since I was going gas, I wanted to try the walbro on it as its even easier to set than the glow carb. (plus it has integrated pump and regulator, and not to mention its alot easier to choke)

Im sure the 120AX would also make a nice conversion, thou I sold mine before having a chance to try it on gasoline.
If you have an airframe for sport flying there is absolutely no reason to go with the walbro IMO. (although I never tested it that way on an airframe)

Im sure the pipe adds more power than the Bisson Pitts muffler if tuned to the prop load you will exert on the engine but Bisson is also very good for its size and price. I'll be using my pitts on the other 160FX conversion for my Sebart Katana 120 airframe for full on 3D.

I am considering to change my oil from very clean burning Castrol scooter 2T to full synthetic Mobil1 2T Racing Oil at the same ratio or abit lower (8%)

10:1 ratio seems more than enough and I'll be sticking to it for a while.

Ive also recorded a video of the engine running, I will be uploading it very soon.

congrats on the success, now someone kit the upgrade so I can get my 1.60 converted!!


matt

Thanks Matt, such a conversion kit may emerge soon - CH ignitions or similar company can provide such a kit. Its just looking at a walbro carb, flange and modified backplate. thats all.

WM Spot On 120 flight ready:

Looks like your gaining about 120 rpm per cm of cut header. As long as your in this range per cut you can go a bit more. When the amount per cm starts to drop then quit.

We have left the 1/4x32 full shielded spark plug lead out of our price list.I have to hand build these and do not have much time to make them. I still have the parts and build them when I can find the time. I thought XuLaing at RCEXL was going to build these caps but he is ill and has not been around for a couple of months. Does anyone no what he is ill from,they will not tell me what the nature of his illness is.
If you use just the little silicone boot it will create a lot of RFI If the ignition has a stranded copper core it will be much worse. RCEXL has tried to find a good 5MM resistor wire but I guess they don't make this in China.There 10MM-CM6 ignitions with resistor wire has gave them a lot of problems. Now he is using solid core copper with a 5K resistor added in the metal cap. Even using a good resistor wire The ignition is very noise with a none resistor spark plug. The NGK CM-6 -10MM is non resistor but they have a full shielded cap for these.
There is probably room on the OS-160 cylinder head to drill and tap for the 10 MM spark plug.This is what we do on the ST 2300.Much tougher and lower priced spark plug. We use two spark plug gaskets on this Mod. I will look into having a Walbro carb adapter built for OS 160.
Do not use much less them 10% oil with a bushing type rod.Do not ask me how I no . The ST 2300 ran for about 10 min when by mistake I put in 40 to one mix in the tank.
I still do not think these conversions are worth the cost and agrevation ,when there are so many good little gas burners available. I no they do not make the power of the OS
but what ever.Terry(TKG) has a Zenoah G-20 on a mini pipe that turns 8800 on a 16x8 APC. Sounds like a glo engine. Maybe this is not good. I do not own a tach,so I do not have all of these RPM problems.
BCCHI

Well, here is a video of the engine setup on test stand, just after I cut the header down by 1 inch.
I forgot to re-adjust the needles after the header mod, both high speed and low speed needles were a little rich.
I know this is not the best video clip - with too much zooming and not focusing well.. lesson learned

[link=http://www.youtube.com/watch?v=k2jBulFVUmc]http://www.youtube.com/watch?v=k2jBulFVUmc[/link]

Oh and, Ive maidened the Spot On 120 and 160 FXG with 17x10 JXF. But this time I tried a new fuel mix - 8.5% oil.. Ran like a clock - no sagging or overheating.
This is probably the max safe zone for oil content - for this engine.

Now its time to complete the conversion of my other 160 FX to 160 FXG.. which will power a SebArt Katana..

thanks to all for the inputs and observance.!

As you know, Ive been using the RCExcl ignition for glow plug thread and 1/4-32 spark plugs.




These are not the best options for reliability as the silicone plug boot keeps sliding out and results in an arc between the boot and the spark plug head. - HUGE RFI!

to overcome this, Ive put a couple of layers of heat shrink on the boot then used a thin wire to crimp the boot in place (without damaging the silicone underneath)

It works for now.. But Im thinking about modifying the 160FX head, to accept standart 10mm CM-6 plugs.



But before doing this, I wanted some feedback. Would the head have enough material, do i need to make other mods other than enlarging the hole to 9mm and tapping with M10 tap?

Would it likely fail in flight? any ideas?

BCCHI - could you post some photos of the ST head?

I always wanted to do this to one of my 160fx's and compare the performance to my Evo 26. It looks like you are getting nearly 1000 rpm more out of the OS! The 8700 rpm quoted by Horizon for the Evo is with a tuned pipe and low load Mejzlik 18X6. The glow 160FX spins that prop at 10,000 rpm.

My concerns for long term use would be the wrist pin seizing in the piston and faster wear on the crankpin and con rod. But then again gas has better lubricity than methanol so maybe the reduced oil won't hurt anything. You could add a couple oz of castor per gallon for additional protection or run Pennziol at 8:1 vs. 10:1.

Too bad nobody makes a sheilded McDaniel Style twist lock plug cap for the ignitions. Installing a cm-6 plug will change the chamber volume and lower compression.

CH Electronics makes a 1/4x32 McDaniel plug cap. It must be built on the plug lead and the 1/4x32 spark plug is $18.

Do you have any pics and details on how it installs on the plug lead?

If it were going to sieze or show signs of wear and performance drop, i guess it would have shown it by now.

Ive run about 4 liters of 8% oil mix thru the engine doing hard vertical 60-100% throttle pattern manuevers with the setup (picture above). And its still incredibly oily inside and a little out. I wipe the oil after every 5 flights with a single small paper towel.. and most of what I wipe comes out of the carb venturi.

It would be like heaven if I could get my hands on those locking type plug caps for these small spark plugs. I use the ones I bought from Just Engines UK for £5.. not that pricey!

So CH ignitions have these locking plug caps in stock? I thought of buying a locking type glow driver and cannibalize it to manufacture a locking type plug cap, but seems like a lot of work.

This way or the other I need a locking plug cap for reliable operation and it would suit me better if I didnt mod the original head.

The CH cap can not to added to a lead. We have to build it on the lead. You have to change the entire lead. The plug lead on most ignitions is not replaceable.
The CH units with aluminum boxes can have the lead replaced. The cap and lead is $14. and the spark plug $18

Does the CH 1/4" plug cap twist and lock like a McDaniel glow driver? This is the design I'd like to see. I've seen an old 1/4" CH ignition on a ST4500 and the guy always had a hard time with keeping the caps on. They may have been abused.

I have well over 80 hours on one of my glow 160fx with no performance drop but the wrist pin had seized in the piston and there was some wear on the big end. It still runs fine and I freed up the wrist pin.

Great to hear your engine is running well.

Hi,
I only have one question, or two,, What is the reason you guys are doing this? Is there an performance gain? Or is it just to save twenty bucks for fuel, (of course the dreaded glow fuel clean-up)

The reason I'm asking, I have an O.S. BGX 3500 on my Pitts.. If there is a performance gain? Then I might like to see what this motor would do..Shouldn't be a problem, Pretty much is the same motor as the 1.60. (sort of)

But if there is no gain in performance, then I will keep cleaning the oil off the bottom..

Thanks,
Don

The gain is lower operating cost. At 8:1 and a Pitts muffler the clean up will be about the same.

The plug caps are not hard to make. I made one from a McDaniel part and it works fine. I don't know how it will hold up in the long run. I hope to make another in the next couple weeks and take some photos of the process.

Thanks for the answer! Maybe I'll try it someday, But I will definitely wait for my warranty to run out!!!

Don.

Actually the clean up has nothing to do with glow fuel.. I wipe a smudge of oil from the bottom with a single paper towel after every 5 or 6 runs.. thats no comparison to any glow engine I had..

Also you guys may be paying 20 or so USD for a gallon of fuel, but I was paying around 40-45 USD for a single gallon of 15% omega glow fuel.. Not to mention 12-14 USD glow plugs..

And after spending around 100 bucks for the conversion, Ive already redeemed all the cost of the conversion.. spending 80-90 USD a weekend is different from spending 10-11 USD for model fuel..

And let me tell you, once you go gas - you cant even think about glow drivers and wiping slimy oil with rubbing alcohol..

I know I will never use anything besides gasoline and electric..

After six, 12 minute aerobatic flights, I would have a thin mist on the belly and tail surfaces. All that is needed to clean my plane is a 1/2 sheet of paper towel. This, flying my Yellow Aircraft 120 size Extra 300L with the 160fx on glow with a Jtec dual snuffler and Hobbico extensions. The same goes for my 1.60 GP Gene Soucy with a Bisson ST 4500 muffler with one exhaust closed and Hobbico extension on my other 160fx. It's a matter of getting the exhaust away from the plane. If I was running a tuned pipe, oil would not be an issue.

Large glow engines get rid of the oil and are not slimers like .40 size slimers.

I still like the idea of flying gas with this engine and would accept the slight drop in performance.

How is your fuel consumption on gas? Have you timed a run at full throttle with a tank of known size? On an APC 18X6 @ 9200 rpm with 5% nitro 20% oil glow fuel I was getting 5 minutes 20 seconds on a test stand and 8 oz tank.