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Old Mar 11, 2012, 03:24 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
Quote:
Originally Posted by Chophop View Post
You may want the carb to be a bit warm. On cool damp days ice can form in them and cause the motor to stop or melt down from a lean mixture. Full scale airplanes have a carb heat lever that diverts air over the exhaust to heat it. Part of the landing checklist to open carb heat. The problem is worst at lower throttle.
The small throat of model engines may greatly intensify the ice problem.
HI CHOPHOP,
You are right
I know exactly what happen in Ice Carburetor condition. I'm a licenced JAR pilot with Single Engine Piston (all type) and fly with General Aviation airplanes. We have in the cockpit an instrument temperature carburator intake air to check it.
With heli or airplane model is also easy to avoid carburetor ice, need only to check site temperature, umidity and dew point..
As the aircraft carburetor vaporizes fuel, it cools the intake air by evaporation. The carburetor venturi also cools the air by adiabatically expanding the intake air, known as the Joule-Thomson Effect. If the air temperature drops below the dew point, moisture in the air condenses into water droplets. Thus, water can be present in the carburetor even when flying in clear skies.

Ice forms near the aircraft carburetor butterfly when water droplets strike parts of the carburetor (typically the butterfly and venturi) that are freezing. Freezing is determined by: the outside air temperature, the temperature drop, and heat absorption from the engine. With the throttle partly closed, such as in a low power descent, you may have a 10" Hg or more pressure drop across the throttle butterfly.
Regards
Claudio
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Old Mar 30, 2012, 04:50 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
HI,
another t-rex 600 converted to gasser: motor OS50 with TT90 Carburetor.
This is the 2nd or 3rd fly to test.
Trex con motore os50 alimentato a benzina verde.mp4 (9 min 25 sec)
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Old Aug 13, 2012, 01:47 PM
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104 Posts
I-FELN

would you be able to post a picture of your TT56 Redline motor ignition sensor location and setup please?

Can you confirm if you are using 40 or 28 deg before top dead center of piston.

What thickness extra spacer did you use on your cylinder head to reduce compression - or are all the spacers the same thickness and you jsut used 2 instead of one?

I'm very keen to have a try of convering a TT56 to gas..so any help appreciated.

Now you have done it - what would be your best choice for ignition system?

Many thanks..
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Old Aug 17, 2012, 03:21 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
Hi JOCKSTRAP

would you be able to post a picture of your TT56 Redline motor ignition sensor location and setup please?
---------
Difficult casue I must desembraque the motor. In any case the first I had the magnet on the cooling fan. Now is located as NCH9 gasoline motor on an alloy ring under the fan.
--------------------
--------------------
Can you confirm if you are using 40 or 28 deg before top dead center of piston.
---------
28 deg if measured from the inner diameter of magnet and sensor, 40 if from outer diameter. look at: http://www.justengines.co.uk/acatalog/info_CDIINST.html
_____________
What thickness extra spacer did you use on your cylinder head to reduce compression - or are all the spacers the same thickness and you jsut used 2 instead of one?
---------
Used two: the stock spacer plus another of 1/10
______________
I'm very keen to have a try of convering a TT56 to gas..so any help appreciated.

Now you have done it - what would be your best choice for ignition system?

Just look at my post 16 for these items.
________________________

Remeber to use tygon tube for gasoline in the tank and the lines to carb.
The cooling system is an important factor in these conversions. T-rex 600 system is more efficient than mine on Titan (add a carter but not so good). wherefor by now I stopped the tests cause high summer temperature till 34C and waiting for better weather in september..
At call if you need others help.
Best wishes for the conversion.
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Old Aug 22, 2012, 08:28 AM
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Thanks kindly for that info..

Looks like a t-rex600N frame is the best to use due to it's efficient cooling..

Last question - did adding the ignition ring under the fan like the NCH9 increase the length of the engine and so the clutch is too high?

Did you have to lower the engine mount by the ring size to allow for this?
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Old Aug 22, 2012, 10:18 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
Quote:
Originally Posted by jockstrap View Post
Thanks kindly for that info..

Looks like a t-rex600N frame is the best to use due to it's efficient cooling..

Last question - did adding the ignition ring under the fan like the NCH9 increase the length of the engine and so the clutch is too high?

Did you have to lower the engine mount by the ring size to allow for this?
no any change to engine mount; found the photos. One of my friends with mechanical skill made the job for me. as you see the sensor is locked under the engine mount, the ring with magnet could have some free degree to fix it at 28.
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Old Aug 23, 2012, 03:22 PM
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Pleasant Valley Modelport
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I always thought this could be done but lacked the little spark plug and ignition system. It surely must have a piston with a ring, and one really nice thing to do if not already is to get a chrome or Alusil plating on the cylinder. It may last a lifetime if the piston is not allowed to get junked up with hard carbon.

There are places in the USA that will do the plating for a surprizingly low cost. At least it used to be cheap.
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Old Aug 23, 2012, 03:26 PM
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Never mind, I checked and the price is going to be more than a whole motor here.
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Old Aug 23, 2012, 03:40 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
Quote:
Originally Posted by Chophop View Post
I always thought this could be done but lacked the little spark plug and ignition system. It surely must have a piston with a ring, and one really nice thing to do if not already is to get a chrome or Alusil plating on the cylinder. It may last a lifetime if the piston is not allowed to get junked up with hard carbon.

There are places in the USA that will do the plating for a surprizingly low cost. At least it used to be cheap.
Hi Chophop,
the piston of TT56 has a ring. Eventually do you think having a chrome or alusil plating on the cylinder would also better support the higher gasser temperature?
Up to date my friend's motor TT53 with gasser conversion has more than 25 hours running and is in better condition than a glow run: no corrosion or carbon dirt.

PS: to day may friend tell me he has reached over 40 hours with the TT53 gasser on T-REX 600
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Old Aug 23, 2012, 04:44 PM
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Chrome is MUCH harder than aluminum and will stay hard at higher temps. There is also Nicasil which I think is harder but high sulpher fuel will ruin it. All around wear elimination is the intent, and yes without doubt a plated cylinder will far outlast aluminum cylinders. The plating is very thin but so hard it can wear out many sets of rings.

Maybe you can get it done cheaper at home. Ferrari uses such platings on their engines. Because it's the best.
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Old Aug 24, 2012, 03:44 AM
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Joined Dec 2005
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The TT cylinder in not aluminum, it is a sleeved engine. The cylinder sleeve has what they call a nano composite plating. I would not replate one. You would also need a ring to match the type of plating.
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Old Aug 24, 2012, 01:41 PM
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Good news, I wasn't sure.
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Old Sep 02, 2012, 06:52 AM
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Quote:
Originally Posted by I-FELN View Post
no any change to engine mount; found the photos. One of my friends with mechanical skill made the job for me. as you see the sensor is locked under the engine mount, the ring with magnet could have some free degree to fix it at 28.
Thanks for the pics - some good ideas there...

I have a 2nd hand redline 53 comming soon to play with
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Old Sep 02, 2012, 12:51 PM
T-REX 250 -450-500-600-700G
I-FELN's Avatar
ITALY, PAVIA
Joined Mar 2009
344 Posts
Quote:
Originally Posted by jockstrap View Post
Thanks for the pics - some good ideas there...

I have a 2nd hand redline 53 comming soon to play with
HI,
TT53 has carburetor with insuletor gasket as TT56. My friend run it cool with gasser on T-rex 600 - Best wishes to your conversion and if possible let me know about result.
Regards
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Old Sep 11, 2012, 12:55 PM
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I-Feln,

I just ordered one of these --> http://www.himodel.com/engines/Rcexl..._90degree.html

But just read on the earlier posts that they maybe can only go to about 10,000 rpm? How many RPM's are you running your redline 56?

Nitro motors usually go easily over 10,000rpm so now i am worried as headspeed in a t-rex600 may be low at 10,000 rpm ?
The stock t-rex600N gear ratio is 8.5:1 so to achieve a headspeed of even 1900rpm you need approx 16,000rpm - Have I purchased the wrong CDI now Please tell me this cdi will work ?

Also - what percentage oil did you find works best - 5% ??
And what was the best octane gas - around 92 ???

I have my motor now - need to wait for ignition and spark plug - and need to order the cylinder gaskets so i can lower the compression..

From early posts is low or high compression better when running gas?
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