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Cox Engine of The Month
November-2022
cmulder's

"Throttle and muffler contraption"



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Post  DaveyMo Sun Apr 24, 2022 3:37 pm

As you can see, this motor is outfitted with an exhaust extension. What model might this have powered?

The snout might make the motor run quieter, but I'm not sure. Am thinking of taking it off to see if there is a boost in power and for easier priming, but that would require fashioning a tool for cylinder removal. The engine turns a 6 x 3.5 prop at 11,000 rpm, though not completely broken in. I think I'll go ahead and give removal a try unless someone suggests otherwise. I'll wait for responses here.

Thanks!

Dave Mo...

Medallion 049 snout Medall12
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Post  balogh Sun Apr 24, 2022 4:00 pm

This muffler was used in some COX cars.

The top fin of the cylinder has flats on which a COX wrench will fit and the removal is easy.

https://coxengines.ca/tooling/cox--049-wrench.html

The muffler causes the performace to drop especially if the cylinder is the so called sub piston induction design. You can verify that if you reassemble the engine without the muffler and check if you see a gap under the piston skirt when it is on top dead center.
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Post  davidll1984 Sun Apr 24, 2022 6:37 pm

Its posible that the use of this exaust collector Raise the cylinder so as to cancel the sub piston induction and lost a bit l compression To i use spécial hi compression glow plug adapter  and I use those on tee dee rc modified engine i use the same parts on this litle rc truck wit rc tuned pipe Medallion 049 snout Img_2319
This parts i use it To rc the engine
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Post  sosam117 Sun Apr 24, 2022 8:15 pm

Watching that video of that Cox crawler was so cool!

I never saw one before.
I would have begged my parents to death to have it after seeing this video (when I was young).

Thanks for a great video and to see you having a great time with the crawler in the snow.

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Post  GallopingGhostler Sun Apr 24, 2022 8:51 pm

balogh wrote:The muffler causes the performance to drop especially if the cylinder is the so called sub piston induction design. You can verify that if you reassemble the engine without the muffler and check if you see a gap under the piston skirt when it is on top dead center.

I haven't done my own personal tests yet, but my personal thoughts are that say, a Medallion .049 with muffler or throttle muffler would benefit from a Sure Start dual bypass with boost ports cylinder and matching non-SPI piston. My impressions were that my late 1970's R/C Bee with only dual bypass muffled performed admirably, similar to a Golden Bee.

Otherwise, the Medallion's standard SPI and single boost port cylinder is at a power disadvantage when muffled.
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Post  getback Mon Apr 25, 2022 5:29 am

The instructions sheet says ( 2 bypass, 1 boost port on each bypass, top fin milled. no SPI (RC version ground for use with throttle ring) https://www.coxengineforum.com/h23-cylinder-identification I would suggest using a Hi comp. head and 3 head gaskets You may get a few more RRRS from removing the pipe and should prime through the venture anyway . Smile
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Post  GallopingGhostler Mon Apr 25, 2022 9:19 am

getback wrote:The instructions sheet says ( 2 bypass, 1 boost port on each bypass, top fin milled. no SPI (RC version ground for use with throttle ring) https://www.coxengineforum.com/h23-cylinder-identification I would suggest using a Hi comp. head and 3 head gaskets You may get a few more RRRS from removing the pipe and should prime through the venture anyway . Smile

Reason why I mentioned 2 boost ports was the last of the Sure Start cylinders being sold by Bernie and Matt had 2 AFAIK, e.g.,

https://coxengines.ca/top-end/cox--049-cylinder-and-piston.html

Cox Engines CA wrote:Features:
Non sub-induction
Dual bypass ports
Dual boost ports - extra power
Slit exhaust to lessen burn risk
Brand new  Original Cox item
(Piston & conrod are current production)

The engine forum listing may be out of date. The extra boost port would provide a slight improvement in power. However I agree with you. On a car, a slight loss of power by the smaller muffler chamber helped to keep the oily exhaust from coating and compromising cooling by keeping it off the cylinder fins and head. A smaller chamber allows more flexibility in a tight engine compartment to not detract from scale appearance. Cox went with the larger muffler with greater expansion chamber on their aircraft, which tells me it was designed to keep power losses to a minimum.
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Post  DaveyMo Mon Apr 25, 2022 12:36 pm

Many thanks to all who have responded. I took Balogh's advice and removed the snout extension no problem. It does have sub piston induction and a single bypass port. I'll give it another run to see if there is any improvement and let you all know soon enough. Will consider the other nifty suggestions. Thanks again!

Dave Mo...
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