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November-2017
MauricioB's

"Cox Tee Dee .010"



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COX TeeDee 09 cylinder booster ports

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COX TeeDee 09 cylinder booster ports

Post  balogh on Mon Nov 21, 2016 5:04 pm

I am the happy owner of 3 COX TeeDee09 engines that I purchased on ebay to support my Cosmic Wind project. 2 are all-new, the 3rd one I currently run in the Cosmic Wind is almost new with apparently low runtime on it.

I checked the cylinder design of the 3 engines and found by surprise, that 2 out of the 3 does not have any booster ports in the bypass ports, while the 3rd one has double boosters machined in the bypass ports on both sides.

Pictured here are the 2 new cylinders, 1 with boosters (the bottom one, the boosters do not seem to have been nicely machined, but their length does not overhang that of the bypass port so it must be alright), the other without (the one on the top) , plus I checked the  the 3rd cylinder of the engine mounted on the Cosmic Wind by removing the glow head, and found no boosters there either.



The oldest of the 3 without flats machined on the top fins, and a younger one with flats for the wrench on the top fin (the one on the Cosmic Wind) do not sport the boosters. Another "young" with flats on the top fin is where I noticed the boosters.

We all know COX engine specifications often varied in order to keep the engines competitively priced, but thought I will ask CEF if anyone knows the above deviation between the 3 cylinders is just a usual variation or there was a certain period of time from when all TD09 engines came with the boosters? Or, instead, the boosters may have been the results of some garage-tuning by the previous owner?
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Re: COX TeeDee 09 cylinder booster ports

Post  Surfer_kris on Tue Nov 22, 2016 12:49 am

It looks home made to me.
I don't remember seeing any booster ports on my own .09 engines, and the ports you show are done after the blackening of the cylinder (which cox would not have done).
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Re: COX TeeDee 09 cylinder booster ports

Post  balogh on Tue Nov 22, 2016 1:10 am

Thanks Kris you must be right it is home made. As iit does not overhang the bypass flutes and thus does not change timing I hope it will have rather positive than negative impact on performance. What do you think?
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Re: COX TeeDee 09 cylinder booster ports

Post  Surfer_kris on Tue Nov 22, 2016 7:14 am

If it is well done, i.e. no errors in the de-burring of the bore etc, then I guess it can only help by enlarging the transferport size. I have never tried anything similar on these engines myself though...
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Re: COX TeeDee 09 cylinder booster ports

Post  KariFS on Tue Nov 22, 2016 7:55 am

There is an old saying, dating back a long time, since it was an old saying already during my moped-hopping-up days:

"The performance modification is considered succesful if more than 80% of the original power is retained" lol!

Anyway, it would be interesting to see an rpm comparison between the original and the modified cylinders Huh...

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Re: COX TeeDee 09 cylinder booster ports

Post  balogh on Tue Nov 22, 2016 8:17 am

Kari,

you from Europe may know the late Czech novelist Bohumil Hrabal, who wrote about his uncle in his renowned book "Capriccio of the Brewery"...old K und K stories from the early 1930-s.

The uncle had a motorcycle that was perfectly operating, but he dismantled the engine into its smallest pieces every Saturday just to check why it was working so good...
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Re: COX TeeDee 09 cylinder booster ports

Post  balogh on Sun Nov 27, 2016 1:39 pm

Surfer_kris wrote:It looks home made to me.
I don't remember seeing any booster ports on my own .09 engines, and the ports you show are done after the blackening of the cylinder (which cox would not have done).

I have just read in the COX Model Engine Handbook (see page 41) that normal TeeDee 09-s with SPI cylinders did not have booster ports, while the Tee Dee 09 R/C engine with non-SPI cylinder had 3 flutes= 1 bypass+2 boosters on each side.

My 09 engine with the boosters has SPI design, so it was not made for the R/C version, and the boosters must really have been added by the previous owner.

Still have not tached the engine - its performance remains unknown until I swap it with the one running on my Cosmic Wind. This latter is getting better the more I use it, leaving no reason for the swap for the time being.
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Re: COX TeeDee 09 cylinder booster ports

Post  Surfer_kris on Sun Nov 27, 2016 3:06 pm

Didn't think of the RC one before, good call.

I've now taken a better look on mine and it is indeed different from the regular TD .09 cylinders. The exhaust port doesn't go as low and there is one additional boost port to each of the transfer port. As said before, theses ports are all made before the blackening of the cylinder surface, and they are all black.

I only have one of the Cox .09 RC, so I don't know if there are others with two boost ports around as well...




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Re: COX TeeDee 09 cylinder booster ports

Post  MauricioB on Sun Nov 27, 2016 9:17 pm

Friends, I have a Dee 09 RC Tee, two Tee Dee 09 and a 09 medallion, I'm going to see the cylinders. I want to highlight the quality of the photos that you are placing, very, very good!Very Happy Thumbs Up
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