It would be neat to have the Glow plug, but also have a contra piston (like some model deisels have) to vary the compression ratio while a Gas/Glow engine is running. Can it be done? Capt,n[:-]

Yes, I'm in the middle of doing that now.

Another thought. Way back before glow, purpose built ignition engines as in O&R and the like had a very small spark plug not unlike glow plugs of today. What if the heads on our conversions used that sort of spark plug? Increased efficiencies due to smaller threads exposed to the combustion chamber? We may find out.

Captain,

Oh wait, I see what you mean. Adjust the compression while the engine is running. I've done that, (on glow at least) on a Norvel .15. That revealed that the .15 and possibly the .25 and the .40 are undercompressed.

See,

http://www.youtube.com/watch?v=_pN6-rgXEFk

Something to consider doing with the Tanaka.

OK, that makes four heads to make. Got to stock up on some large diameter aluminum bar. [X(]

Capt, i am building a 18cc feather lite right now that i will be able to adjust the compresson while it is running, it is also gas & glow. This is all R&D and lots of fun and if is does not work i can alway say been there and done that.
Ken

AV8TOR,

Using the "Corrected Compression" determination given in the links RingWinger posted I belive is the same as the "effective compression" you were refering to since it takes the exhaust timing out of the picture by using the swept volume above the exhaust port.

Using this method, I determined the CCR for the Stihl, Shindawa, Echo 38 and McCulloch 25. Both the Echo and the Mac run well on the glow/87octane gas mix. The CCRs are as follows:
Stihl -- 10.61
Shindawa --9.85
Echo -- 7.89
Mac -- 7.14

The most significant differences between the similar engines is the shape and volume of the combustion chamber at TDC, with the Mac and Echo having about 30% more volume than the Shindawa and Stihl.
I ran the Stihl on EI with fixed timing at 20, 25, 28, 32, and 35 deg BTDC. The Stihl began to show some vibration(shaking) at the 3 to 5 krpm range at 28 deg. At 32 deg it increased, but was still tolerable. At 35 deg the vibration was unacceptable. I never heard any sounds like detonation, but the could have been masked by the prop and exhaust noise.

From this information I believe that my conclusion of needing to increase the octane value of the mix for the Stihl and Shindawa is valid.

Andy,

Regarding the head volume. I believe that I would shoot for a Corrected compression ratio of between 7 and 8. For my 23 cc Shindawa this would translate to a head volume of about 2.7 to 2.8 cc.

Next step, try some octane addatives and see what happens.

Another thing you could try is to leave the nitro out of the mix. At those compression ratios, they should run well without nitro in this case I believe. However, I think you will probably find max power by lowering the compression as you say, and leaving in the nitro. It will be interesting to see if any additives you try will "play friendly" with the glow plugs...

Another thing to consider of course, is the exhaust timing. Do those engines have "room" for more exhaust timing. If the exhaust timing is low, consider running it up to around 160 degrees to lower the effective compression ratio a bit, gain power, and possibly run ok on this fuel mix. Much over 160 is getting into tuned pipe territory on the exhaust timing.

Just so everyone has all the info possible, altitude, barometric pressure, temperature, and to a lesser extent humidity also affect "glow timing" and compression. An engine that is overcompressed at sea level for example, may not be at higher altitudes.

It was a common "trick" of mine to advance the timing on cars I tuned that remained at higher altitudes. They wouldn't ping, and had better power and throttle response. I've also had glow engines that would tolerate for example, 15% nitro at a field elevation of 4500 feet, but not when run later at sea level....

AV8T0R

CaptinJohn, You was right. The engine has allot of compression. I cut the nitro down and it doesn't vibrate hardly at all now. Now It will run good wide open and then it would just die it was doing this before the vibration as well. I keep the heat on with the glow plug. Any suggestion?[sm=confused.gif][sm=confused_smile.gif]

Hi guys,
I have been grappling with how to get a combination of large capacity engine, light weight and cheap fuel consumption. Generally speaking gas engines are more complicated, more expensive and heavier but cheaper to run. Conversely large glows are cheaper to buy, simpler, lighter but dearer to run.

Have you guys discussed or thought about adding needle bearings to a glow motor so it will run with a much lower oil content in the fuel mix? Say 40 or 50:1.
This would allow for a simple methanol/oil mix compatible with the existing engine's parts/fuel lines etc and would alleviate the need for plug conversions, presumably timing issues would not exist and there would be no need for 'exotic' fuel mixes.

I realize this solution would be limited to about 35 cc (the largest glow motors currently available). The Moki/Mark 2.10 springs to mind as an option.

Your thought would be appreciated [8D]

Air Hobbies offers conversion services for installing needle bearings on the ST and Moke connecting rods. If I recall correctly, Ralph Cunningham (rcignition) has performed this on the ST in the past, but does not any more. I believe the reason given, at least for the ST is that the crankshaft metal is too soft to run needle bearings directly on the crank pin. I also have read that some have ground down the crankpin and pressed on a hardened sleeve for the needle bearings to run on. I don't know how successful this approach has been.

Yes, here,

http://www.rcuniverse.com/forum/m_45...page_23/tm.htm

We have discussion about running diesel engines on a no ether based fuel. Later posts include various oils and low oil mixes. The issue is the plain bushed rod. The bushed rod at the crank is not so much an issue maybe because this end gets LOTS of fresh fuel/lube and the pin rotates through 360 degrees for effective distribution of lubrication. the pin at the piston end only oscillates through a shallow angle and does not get a lot of fresh lube circulating. This is really where we need a needle bearing. Illustrated is a rod from the old Webra .60 Blackhead. Note the needle bearing at the piston and not at the crank. This worked very well for many, many gallons of fuel. The piston pin wear is non-existent but note that there is ALSO no wear at the crank end. And the crank end is plain, brass bushed.

So the solution to a 50:1 mix, glow, gas or diesel seems to be in getting that piston pin a bearing of some sort. Here, http://store.microgroup.com/catalog/...talog_5-16.pdf you can get very small, thin wall tubing. The idea is to use the right size as the outer race along with needles made from .015 piano wire running directly on the pin. This would be full complement, without a cage and free floating. Maximum number of needles in a compact space. As such, we can make up a needle bearing for an engine as small as the Norvel .15 as discussed. But the problem is getting the tubing. An attempt to do so was met with minimum quantities, minimum billing etc. Am looking for another source.

But the Tanaka, with bearings all over, will be dieselized and 50:1 diesel fuel mixes will be tried along with exotic gas and glow fuels. I've even had luck in running an all Biofuel mix in the small .15. That's with NO added lubrication, only 100% Biodiesel acting both as fuel AND as lubrication. Sure enough though, the rod wore out at the piston end but there was no wear whatever at the crank end.

Hello Andy,


Micro Needle Bearings:

I don’t doubt you skills to be able to create a needle bearing, but I think you’ll find that it is much nicer to buy this product.

There are many sources for these bearing and I have attached a PDF showing a listing of micro needle bearings.

Micro Needle Bearing PDF: http://www.impactbearing.com/brochurepg30.pdf

Store Front: http://www.impactbearing.com/needlebearings.html

Note the smallest on this PDF is for a 0.118 shaft and the outer dimension is 0.256. It would be extremely unlikely that you could make such a precision bearing without complex grinding equipment to create these various components. This bearing is rated a 46,000 RPM.


You can look here for more Micro Bearing store locations: http://www.thomasnet.com/nsearch.htm...sec=prodsearch

I completely agree with you on the need for a needle bearing on the piston end of the rod. This will allow for the use of low cost fuels and much reduced oil content.


Various fuels:

I have run a mixture of 20 methanol and 80 Coleman Lantern fuel mixed with Cool Power oil. I found that the Cool Power oil is low cost at $7.50 per quart in the USA.

I purchase the oil from Horizon Hobbies at this location:
http://www.horizonhobby.com/Products...?ProdID=COO500

I had difficulty finding a cost effective synthetic oil that would hold methanol and Gas/Lantern fuel together. To my great delight Cool Power Oil does a wonderful job and it leaves my engine and airframe clean after extended runs.

I have run this mixture in both my gas conversion engines and my glow engines. It does run much hotter than plain methanol. The fuel has a very high energy content, burns clean and has a very pleasant odor that reminds me of nice evenings reading by a Coleman powered lantern.

I also use the Wal-Mart brand of lantern fuel called Ozark Camping fuel and it cost about $3.80 per gal USD.


Have fun,

Kelly

RingWinger,

I just bought 2 gal of Cool Power oil for $15/gallon. Shipping was $14 so that comes out to $22/gallon. The web site is: http://www.tommyskarts.com/Cat.Oils.htm

Guys...Want to measure oil ratios the easy way. I seen a neat little gaget at Menards. It is a clear syringe type of thing. All you have to do is suck the oil of your choice up to the mark on side. There is a mark for any ratio you may need. It is based on one gallon of fuel. I should have bought the darn thing! Capt,n

Wvarn/Will

Hello Will,

Which version of the Cool Power oil did you buy at the Cart Shop you listed above?

I thought others maybe interested in this data too.

Kelly

Kelly,

I bought the CoolPower Medium (CP 1001MGO) /with castor. They have 3 grades, light, medium and heavy. I just took a guess and split the difference with the medium.

Will

Hi Kelly,

Yes, the bearing people know their stuff and do it right. And a needle bearing that'll handle 46K is impressive. I've been in the bearing business for some 35 years and am familiar with most types and their potential. In our case though, at least for the test bed Norvel .15, an OD of 1/4" is a bit too big. You also still need some meat in your rod to carry the bearing so it looks like the best you can do is to needle an engine the size of a .40 or a .60. I'd do that but for experimenting, the little .15 presents the biggest challenge and also is a lot easier on the fuel bill. I suppose what I mean is that if it can be done with a .15, then everything follows from there. My thinking is that for an oscillating application, a less precise bearing may at least prove the concept.

And as luck would have it, I finally found a source for Cool Power oil at a LDHS. It cost me 12 bucks a quart plus 6 dollars shipping but I was still glad to get it. On a rare warmer day I gave it a try at 20% with store bought methanol at 80%. NO nitro. To my delight, the Norvel .15 really liked it, idle was good and top end was very smooth. Didn't jot numbers down (fingers numb) but I then went and ran 20% nitro Omega and found I only gained 300 RPM at the top. And, get this, the idle was lower and a tad steadier on the simple, Cool Power mix. I AM A BELIEVER. That is some quality oil. Many thanks.

I was about to try CP oil in diesel fuel but found that my head had once again, developed a stress crack. Got some redesigning to do,,, again. [>:]

But this IS a gas conversion forum so here's what's happening there. I just received a brand, spanking NEW Tanaka for conversion. This little beauty just OOzes with quality. No weed whacker of unknown pedigree here. This one will be converted to be a gas runner with stock ignition and it'll be interesting to see how it compares to the other. A big plane is being contemplated. As I haven't flown a biggie for twenty years, I'm looking for suggestions. Something basic as a test bed but something that'll also do some decent aerobatics. Maybe just another big Ugly Stik but this time LIGHT. No door skin ribs this time. (That was the thinking back then).

So we now have Klotz Benol, a castor that will mix with gas, kerosene AND methanol. And we also now have a synthetic that will do that as well. We have tremendous potential here, I think. I like your mix and it'll be the first one I try but what percentage oil are you using? My thinking is a blend of the CP and the Benol.

Cappie,

Seen one of those at the new Home Depot. Guess I gotta get me one. Neat.

Andy, Will, et al

Cool Power Oil selection:

Thanks Will for telling us about your selection of Cool Power blends. For clarification I should say that I use the 100% synthetic Cool Power (Green) version. The selection of various blends of Cool Power may affect the ability to mix with various fuels. I don’t know the affects of having Castor oil mixed into the Cool Power oil, since all of may mixtures use the straight synthetic version of Cool Power.


Mixing ratios:

Andy, to answer your question “what percentage of oil are you using�.

When I run glow engines I use 15% Cool Power oil regardless of the kind of fuel I’m planning on using.

When mixing fuel for my gas conversion engines I first mix the methanol and Coleman Lantern fuel together, typically I use 20% methanol and 80% Lantern fuel, but I’ve tried many variations of these two fuels. Then I add the oil as outlined below:

First I mix the methanol and Lantern fuel together in a clear plastic jug, then I slowly add Cool Power oil until to two fuels combine into a clear mixture, then I add just a bit more oil to make sure they stay suspended together. The amount of Cool Power oil required to make this mixture stay together varies somewhat depending upon the quality of your methanol. Since methanol is extremely hydroscopic in nature you must vary the amount of Cool Power oil slightly, but I would venture to guess that this mixture requires 4 to 5 % Cool Power oil. I don’t pay a great deal of attention to the exact amount after I determine that I have exceed the minimum mixture ratio of 2 % total oil required by my engines.

Thus it is safe to say that you have to custom blend your percentage of oil to meet the Polar/non-Polar requirements of your fuel. I just happens that not only is Cool Power oil a great lubricant it also does a fantastic job making this tertiary blend possible for us to experiment with in our various engines whether they are gas or glow power engines, and perhaps diesel too.

It maybe possible to mix methanol and Kerosene together using straight synthetic Cool Power oil, creating a fuel that will work in a hybrid engine that uses an adjustable Contra-Piston with a Glow Plug on the tip of the Contra-Piston. Of course this same setup would work well with methanol/gas/Lantern fuel too. This arrangement allows for infinite timing setting selection while the engine is running.


Kelly

Has someone converted their weedwacker engine into a contra piston head configuration??? if so do you have pic's to post so we can see it !!!, what kind of succes have you had with this
configuration ???

WVARN1957 have you tried your gas/glow mix with AVgas for your high compresion engines????

I haven't tried AvGas yet. Just haven't made it by the local FBO to get some. I would prefer to not use the organo metallic AntiKnock (MMT,TEL) because of the potential effect on the glow plug. I got one run on the little Shindawa with 1/3 ST mix and 2/3 93 octane before my wife came back from shopping. The 93 octane here has ethanol (10%). The first run vibration was down significantly, but still not as smooth as it was runninng on EI. I'm going to try the next run with the same mix, but adding 10% toluene to the gas. I also tried increasing the exhaust back pressure with little effect other than dropping the rpm.

Ethanol is also a good octane booster, however with the gas already containing 10% I don't know if more will have any effect.

Regarding the CoolPower Oil w/castor. Iprimarily got it for mixing glow fuel, but this afternoon mixed 2cc oil with 20cc gasoline. It went right into solution. The mix is standing to see if there is any seperation.

Will

Not yet, but I'm working on it. This is an old Tanaka .23 in very good shape. Externally it was a mess. Internally, it was impeccable. When I turned down the top to take a head, I noted that the chrome layer seemed to be visibly thick as in more than a thin, microscopic layer. by the look maybe .010 thick. Is that typical?

At any rate, this engine will get the diesel head, a glow head and also I'm going to look around for one of those itty bitty spark plugs as used years ago on the early MODEL spark ignition engines.

I've seen a number of gas conversions and most of them look good. Some have awkward backplate mounting arrangements. Not this little Tanaka. The pull start carrier is bolted on with four equally space bolts and the flange makes an excellent backplate mount. In other words, it bolts directly to the firewall. All you have to do is trim off the magneto shroud and you end up with NO excess material anywhere.

Kelly,

Thanks for your mixing instructions. Looks like we have two universal oils in organic and synthetic versions to experiment with.

Will,

Here,

http://www.permatex.com/documents/ms...lish/12010.pdf

is an octane booster that has 60% kerosene, some naphtha and Stoddard solvent.

The TDS says it contains MMT, Powertain and,,, nitromethane??

After 4hours in the freezer, the CoolPower Syn w/castor has not seperated. Mixed 2cc with 20cc 93 octane gasoline w/10%ethanol.

Will

So WVarn how did the fuel mixture worked out????? have you tried it on big CC engines??(45 or more)

Aero nut,
Tests on the 23cc Shindawa indicated that higher octane fuel helps. However before I could finish, it developed a carb problem and my wife insisted that I help get things ready for the Holidays. Waiting on a gasket set and finishing the HD list.

Besides the Stihl 35cc I am going to try an Echo 38cc and a Zenoah 40cc that came out of a backpack blower. I don't have anything in the 40 + range but a 75cc poulan and 81cc Homelite.

Will

Thanks for the update, I know is hard to argue with "WIFE" so it's best to keep it in PEACE!!!!!
Let us know your results with the bigger bore engines.
Merry christmas and happy new year for you and your familly.
Your buddy from down Baja.
Bill Pomplun A.K.A. Aero Nut.