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Cox Engine of The Month
Compressor charged TD049
Page 1 of 1
Compressor charged TD049
I thought this weirdo topic title will attract some attention and more importantly, opinions:
With properly set and fixed propeller, the blade passing the air intake extension that I have added will (?) force additional air and thus charge into the crankcase through the crankshaft opening. Just like with real size engines, this may add power - and fuel consumption for sure.
I used a plastic shrinking conduit (I am not sure if this is the proper terminology) that electricians add to cable ends then heat it by hot air to shrink and seal. So I did not vandalize any part of the engine (I would never do), and I will simply pull it off in case I am fed up with it because it does not have the desired effect. I think I will tach it tomorrow with and without the weirdo black thing.
The options I expect:
1. Brute power increase, maybe 1k additional rpm with the same prop
2. Excessive engine wear...I am particularly concerned with the crankpin and conrod balljoint longevity
3. Overheated engine...to avoid it, I will add one more shim under the glowhead.
4. Nothing will happen and I will be ashamed of having tried to kill this little jewel
But I cannot help my curiosity...
Your opinion, please.
With properly set and fixed propeller, the blade passing the air intake extension that I have added will (?) force additional air and thus charge into the crankcase through the crankshaft opening. Just like with real size engines, this may add power - and fuel consumption for sure.
I used a plastic shrinking conduit (I am not sure if this is the proper terminology) that electricians add to cable ends then heat it by hot air to shrink and seal. So I did not vandalize any part of the engine (I would never do), and I will simply pull it off in case I am fed up with it because it does not have the desired effect. I think I will tach it tomorrow with and without the weirdo black thing.
The options I expect:
1. Brute power increase, maybe 1k additional rpm with the same prop
2. Excessive engine wear...I am particularly concerned with the crankpin and conrod balljoint longevity
3. Overheated engine...to avoid it, I will add one more shim under the glowhead.
4. Nothing will happen and I will be ashamed of having tried to kill this little jewel
But I cannot help my curiosity...
Your opinion, please.
balogh- Top Poster
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Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Compressor charged TD049
Interesting. I added a forced air intake to my reed speed plane this year. I don't know if it helped performance but it certainly didn't hurt it either. I'm curious to see what tach numbers you come up with.
Jim
Jim
JPvelo- Diamond Member
- Posts : 1972
Join date : 2011-12-02
Age : 57
Location : Colorado
Re: Compressor charged TD049
I vote for #4. If you were using bladder pressure I can see an increase possibly in economy due to not losing fuel out of the venturi. A engine on draw is only going to take in so much air. The only real way to see a benefit of this is to open the venturi. The downside is that opening up the venturi is going to compromise fuel draw. There's no need for a venturi to run this engine. I run TD's with the venturi completely removed and only a spigot directing fuel into the crank. This certainly yields more rpm's but not 1000 more. Ken
Last edited by Ken Cook on Sat Nov 22, 2014 11:49 am; edited 1 time in total
Ken Cook- Top Poster
- Posts : 5637
Join date : 2012-03-27
Location : pennsylvania
Re: Compressor charged TD049
Ken Cook wrote: I vote for #4. If you were using bladder pressure I can see an increase possibly in economy due to not losing fuel out of the venturi. Ken
You maybe right..COX may have found the optimum air intake inclination for the TD-s 50+years ago...will see...
balogh- Top Poster
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Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Compressor charged TD049
Its a DORK TUBE! As in if you crash it should prevent dirt from going into the engine.
Tach it with a straight tube on the intake too, and a straight tube cut at an angle...if you are willing to experiment some.
Phil
Tach it with a straight tube on the intake too, and a straight tube cut at an angle...if you are willing to experiment some.
Phil
pkrankow- Top Poster
- Posts : 3025
Join date : 2012-10-02
Location : Ohio
Re: Compressor charged TD049
2-stroke tuners often play with intake lengths, both before and after the carb. Maybe you could make some different (length, taper) velocity stacks? Or even shim the carb so that it is further from the crankshaft port? The air volume in the intake resonates as the port opens and closes, so with an optimal intake length and intake air velocity you should get more air and fuel into the crankcase. Just make sure that the pressure wave is right at the port area at the precise moment the port opens, and that the wave lasts just a little longer than the port is open. Easy as that
The ram air effect that you are looking for should work too since you are running "wide open throttle", so there is no problems with low rpm throttle response and such.
EDIT: I meant to say SHIM, it was bleeped so I may have accidentally said shi*. Sorry, that was the autocorrect fellow inside my iPad speaking, must have a little talk with him
The ram air effect that you are looking for should work too since you are running "wide open throttle", so there is no problems with low rpm throttle response and such.
EDIT: I meant to say SHIM, it was bleeped so I may have accidentally said shi*. Sorry, that was the autocorrect fellow inside my iPad speaking, must have a little talk with him
Last edited by KariFS on Sun Nov 23, 2014 1:54 pm; edited 1 time in total
KariFS- Diamond Member
- Posts : 2044
Join date : 2014-10-10
Age : 53
Re: Compressor charged TD049
As a follow up to this topic, I mounted the TD049 with the air intake extension on my SEED and tried it in flight...I did not tach it because I was alone with no co-pilot and wanted to make use of the time while people walking their dogs and getting mad at a non-silenced COX were still breathing heavily in the corner of their bedrooms after some heavy Sunday lunch.
While I have not tached it my impression is that option No 1 occured: brute power...no engine damage..no overheating...not fealing ashamed...It is a replavcement now of my TD050 RC and the difference in speed is quite obvious.
While I have not tached it my impression is that option No 1 occured: brute power...no engine damage..no overheating...not fealing ashamed...It is a replavcement now of my TD050 RC and the difference in speed is quite obvious.
balogh- Top Poster
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Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Compressor charged TD049
In theory at full throttle in the air you should now be able to open up the needle valve richer than if you didn't have the extra ram air going into the intake. So its a no brainer more fuel and air over stock set up equals more power.
The venturi is isolated from heat some what with the use of a plastic carb body keeping the incoming fuel cooler for a hair longer. I wonder if you had a ceramic carb body with a built in intake as shown if there would be even further gains. The car guys have some aluminum pre coolers with built in filters to gain an edge / about twice the length of a normal filter with cooling fins.
The venturi is isolated from heat some what with the use of a plastic carb body keeping the incoming fuel cooler for a hair longer. I wonder if you had a ceramic carb body with a built in intake as shown if there would be even further gains. The car guys have some aluminum pre coolers with built in filters to gain an edge / about twice the length of a normal filter with cooling fins.
1/2A Nut- Top Poster
- Posts : 3537
Join date : 2013-10-20
Age : 61
Location : Brad in Texas
Re: Compressor charged TD049
I have not replaced the ventury this is the original aluminum stock item that was on this TD049 when it came out from the maternity home Santa Ana California .
I guess it is the air and not the fuel than we want to keep cool so that with an equal volume of air gulped by the engine more mass of air enters with which more fuel can be burnt thus more power generated.
The fins on the air intake you mentioned are similar to the turbo-charger cooler on diesel engines serving the above purpose.
I guess it is the air and not the fuel than we want to keep cool so that with an equal volume of air gulped by the engine more mass of air enters with which more fuel can be burnt thus more power generated.
The fins on the air intake you mentioned are similar to the turbo-charger cooler on diesel engines serving the above purpose.
balogh- Top Poster
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Posts : 4958
Join date : 2011-11-06
Age : 66
Location : Budapest Hungary
Re: Compressor charged TD049
Right the plastic carb body isolates the aluminum venturi from the rest of the metal engine keeping it cooler my nature big plus. If cooler fuel is mixing with the air doesn't warm up the mix prior to entering the combustion chamber. Cold air being more dense mixed with the fuel helps to reduce heat in crank case and crank all a win win.
1/2A Nut- Top Poster
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Join date : 2013-10-20
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Location : Brad in Texas
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