Tanaka conversion
01-02-2007, 01:24 AM
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Tanaka conversion
Hello gassers,
I'm in the process of converting a used Tanaka 23 and also a new 26cc, to diesel. Both appear to have the same bore with the latter being a bit of a longer stroke.
The head of the cylinder has been trimmed off and a clamp down, diesel button has been made. Along with this, a button for a stock glow plug and a button for a spark plug will also be made.
The idea is to compare the merits of the various fuels on the same engine. It's been twenty years since my Quadra days and things sure have changed a lot.
I note that the O'Neill folks offer some interesting performance enhancing products. Reed kits, stuffed cranks, porting mods and the like. None of this is for aircraft but I wonder if anyone has had any experience in this area.
I'm not a power demon but the idea is to have the best power to weight ratio engine. This allows you to run a lighter engine on the same aircraft and that makes for a lighter and better flying airplane. The diesel converted engine along with the special head comes in at 32 ounces. The stock engine with all the ignition bits weighs 48. Anyway, a couple of questions come to mind for those more experienced.
The reed kits offered are meant for the stock intake. I can imagine some inefficiencies here. What of adapting the kit to the bottom of the case and plugging the stock intake? This has been done to Cox .049 reedies with improved power and smoother running.
The Tanaka comes with a 14mm spark plug. Any advantage to going to any other size, thread wise. How about heat range etc.?
I'm contemplating converting to a ringless engine. Why not an AAC engine in these large sizes? All I need is a piston a bit larger than 33mm. The Tanaka's chrome bore appears to be more than just a thin, sprayed on layer of chrome. I'll check with them first, but with diamond paste on a homemade lap, it ought to be doable to apply a little bit of a taper. Same with a modified or even custom made piston.
These engines are meant to resist a gritty environment. Do we need double lip, spring loaded seals? Why not a single lip with the spring taken out? Or leave them out altogether and just install sealed bearings. They're sealed for life, after all. And these have virtually no load/drag. So with AAC and no drag from rings or seals, would all of that do much for power?
The second hand Tanaka is in excellent shape inside. But is there any value to cleaning up the bore with a mild lapping compound to introduce some fresh crosshatching?
Then there's the throttle. Pictured is the one that came with the new engine alongside a K&B .60 carb. The bore in the barrels is the same. And hey, the Walbro has a drum valve that moves laterally to affect a leaner mixture at idle. Just like a stock, RC carb. Last I remember, gassers came with butterfly valves.
I understand that glows need more fuel air mix than gas and diesel uses less than gas. A standard carb can have various barrels made to accommodate and hey, look, a real, easily adjustable needle valve. Fuel delivery? Muffler pressure? Or how about case pressure through a check valve. Is a check valve needed?
The original idea for the diesel conversion was to eliminate the ignition components for a lighter engine. Plus, diesels give you more punch, at least more than glow, so we might swing a bigger prop with more efficiency. But I note where some of you guys have been running gas and or gas/methanol mixes on just a glow plug, energized or not. Neat and that does the same thing. Except for the torque aspect. I've read most of that thread, I don't recall seeing discussion about prop sizes when converting gas to glow. Any thoughts on that?
Pictures below.
I'm in the process of converting a used Tanaka 23 and also a new 26cc, to diesel. Both appear to have the same bore with the latter being a bit of a longer stroke.
The head of the cylinder has been trimmed off and a clamp down, diesel button has been made. Along with this, a button for a stock glow plug and a button for a spark plug will also be made.
The idea is to compare the merits of the various fuels on the same engine. It's been twenty years since my Quadra days and things sure have changed a lot.
I note that the O'Neill folks offer some interesting performance enhancing products. Reed kits, stuffed cranks, porting mods and the like. None of this is for aircraft but I wonder if anyone has had any experience in this area.
I'm not a power demon but the idea is to have the best power to weight ratio engine. This allows you to run a lighter engine on the same aircraft and that makes for a lighter and better flying airplane. The diesel converted engine along with the special head comes in at 32 ounces. The stock engine with all the ignition bits weighs 48. Anyway, a couple of questions come to mind for those more experienced.
The reed kits offered are meant for the stock intake. I can imagine some inefficiencies here. What of adapting the kit to the bottom of the case and plugging the stock intake? This has been done to Cox .049 reedies with improved power and smoother running.
The Tanaka comes with a 14mm spark plug. Any advantage to going to any other size, thread wise. How about heat range etc.?
I'm contemplating converting to a ringless engine. Why not an AAC engine in these large sizes? All I need is a piston a bit larger than 33mm. The Tanaka's chrome bore appears to be more than just a thin, sprayed on layer of chrome. I'll check with them first, but with diamond paste on a homemade lap, it ought to be doable to apply a little bit of a taper. Same with a modified or even custom made piston.
These engines are meant to resist a gritty environment. Do we need double lip, spring loaded seals? Why not a single lip with the spring taken out? Or leave them out altogether and just install sealed bearings. They're sealed for life, after all. And these have virtually no load/drag. So with AAC and no drag from rings or seals, would all of that do much for power?
The second hand Tanaka is in excellent shape inside. But is there any value to cleaning up the bore with a mild lapping compound to introduce some fresh crosshatching?
Then there's the throttle. Pictured is the one that came with the new engine alongside a K&B .60 carb. The bore in the barrels is the same. And hey, the Walbro has a drum valve that moves laterally to affect a leaner mixture at idle. Just like a stock, RC carb. Last I remember, gassers came with butterfly valves.
I understand that glows need more fuel air mix than gas and diesel uses less than gas. A standard carb can have various barrels made to accommodate and hey, look, a real, easily adjustable needle valve. Fuel delivery? Muffler pressure? Or how about case pressure through a check valve. Is a check valve needed?
The original idea for the diesel conversion was to eliminate the ignition components for a lighter engine. Plus, diesels give you more punch, at least more than glow, so we might swing a bigger prop with more efficiency. But I note where some of you guys have been running gas and or gas/methanol mixes on just a glow plug, energized or not. Neat and that does the same thing. Except for the torque aspect. I've read most of that thread, I don't recall seeing discussion about prop sizes when converting gas to glow. Any thoughts on that?
Pictures below.
01-02-2007, 11:32 AM
#3
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RE: Tanaka conversion
In fact, an ad right on this page for their reed kit alerted me to their existence, here,
http://www.oneillbrothersracing.com/
http://www.oneillbrothersracing.com/
