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Cox Tee Dee 049 High Performance Cylinders

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Old 04-07-2011, 02:35 PM
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Cox International
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Default Cox Tee Dee 049 High Performance Cylinders


For those of you looking for a replacement Cox .049 cylinder/piston, we have modified a cylinder/piston assembly to suit. See here:
Specifications:
· Exhaust ports: Open style
· Bypass flutes: 2 (one per side)
· Boost ports: 2 (one per side)
· Piston: SPI (shortened and lightened)
The porting inside is the same as Cox used in their later-year Tee Dee engines. However, instead of cutting the exhaust ports lower (to induce SPI) we opted to shorten and lighten the piston instead. The reduced mass makes for a higher performing setup.
This cylinder/piston assembly should equal or exceed OEM performance and can be used on any Cox .049/.051 engine, whether Tee Dee, Medallion or reed valve engines.
When used in conjunction with reed valve engines we recommend the use of our Killer Bee/Heavy Duty crank to minimize crank failure.
Bernie
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Old 04-07-2011, 07:45 PM
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GeorgeG97322
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Bernie,

Here's a good cylinder cut pattern for a high performance TD 049/051

I would be interested in some of these...


George
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Old 04-08-2011, 06:09 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Thanks George,

What you seem to be referring to is the porting in some of the early-version TDcylinders. However, contrary to popular belief, the newer 2-port version actually outperforms the version you show. Here is a copy and paste from an email I received for a former Cox engineer who was instrumental in developping the TD engine:

We found the two boost port version ran higher rpm than four. The reason is that it introduces a swirl to the mix that enhances combustion. Four ports are too symmetrical. This trick was used in the Killer Bee, Tee Dee and Venom. I picked up the hint from the “Two Stroke Tuner’s Handbook”, a long out of print 2-stroke bible.

This was the reason that we decided against making cylinders with the 4 ports. I realize they can sell for more $$'s because some modellers believe that 4 is better than 2 but still...

Bernie
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Old 04-08-2011, 07:03 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Bernie,

Will these TD cylinders / pistons work well with the Ace throttle sleeve's?

I remember seeing the SPI makes the sleeves not as effective.

I use the Ace throttle sleeve TD .049 / .051 setup on all my 3-channel scale models.

Thanks,
Brian
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Old 04-08-2011, 07:23 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Nice work!
Is the cylinder bore tapered?
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Old 04-08-2011, 07:53 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

SPI has no bearing whatsoever in regards to using throttle rings so, yes, they can be used.

And, no, the bore is not tapered.

Bernie



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Old 04-08-2011, 08:40 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Very nice Bernie,

The cylinder pattern I provided was the Dale Kirn/Jim Wade 1/2A Proto record engine spec. from 1976. It was a high rev capable Tee Dee on very high Nitro fuel.

I do understand the idea of fuel swirl from a schnural type engine, but does having two exhaustports negate the swirl effect? Most modern engines have two intake ports, one boost portand only one exhaust port.

George
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Old 04-08-2011, 09:09 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

I think those are similar to Reggie's with the 2 boost, 2 port, machined piston setups (Except Reggie left the exhaust side with the little "anti-burn" strakes)

I think I have bought those from you Bernie as well. Are they different from the machined piston setups you sold in the past?

I've been using those to in combination with a Galbreath head and HD nelson plug (1 shim) with pretty much all my 049's with excellent results. The performance is outstanding and the light piston might actually help on the ball joint resets as I have not had to mess with any of mine more than once or twice once they "settle" as long as I run 6 X 3 props to keep the revs sane. ( 16,000 RPM with the Black Widows, 18,500 Medallion static on a 6 X 3)

At those RPM's I have not had any issues with the crankshafts outside of wearing-out a couple crankcases (After several hundred flights ) The throttling effect is fine with the exhaust rings.

I have another question: Bernie, did you guys try to use those on the SuresStart throttle combining an exhaust throttle ring with the throttle valve? I was thinking about purchasing a throttled Surestart and experiment with the setup. Since the SPI somewhat negates the intake throttle effect, the ring should make-up the difference? I though it would be worth a try since this is such a "Step-up" above the non-SPI performance of an 049..
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Old 04-08-2011, 09:10 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Yes, George, that is what I was referring to as well, the old Cox drawings (we have them all here). What the engineer was referring to is that by removing 2 of the channels it induced a swirl and increased performance.

It was Larry Renger who improved Dale Kirn's design and came up with the 2-port version. I have not run comparison test myself but Larry is known for his competence, as is Dale Kirn, of course.

Bernie
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Old 04-08-2011, 01:57 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

We had some testing done (see below) and, as a result, will now be supplying our new cylinders with a regular piston (instead of the SPI one) as that combination produces the highest RPM, even outperforming the later-year #4 stock TD cylinders.
We will also run tests with a reed valve engine and suspect that SPI will actually make a difference with those.
Bernie,
Engine used was my stock TD.049 with stock Hi-Comp Cox Glow Plug and Cox 5x3 “flexible” Black Prop. Fuel was Wildcat 25% Nitro with 18% Caster/Synthetic Oil Blend of which I added Castor to bring the oil to 23%.
1) Stock Cox TD .049 (this is with the original Cox #4 TD cylinder)……….19,650 RPM
2) TD .049 with stock piston and modified cylinder….………………………20,000 RPM
3) TD.049 with SPI piston and modified cylinder…….………………………18,600 RPM
The SPI piston was very hard to start and didn’t compare with the stock piston BECAUSE it was cut too short. The SPI gap with the modified piston in either the stock or modified cylinder was almost “three times” greater than that of the stock TD piston and cylinder. Too much air was allowed under the cylinder. I also think the large gap affected the engine’s timing.
I am not sure SPI actually does much based on my testing. The modified cylinder with a stock piston, gave the best performance, even better than the TD cylinder.
Mike
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Old 04-08-2011, 02:07 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Phile,
We have not tested that setup but I am not so sure it would work as intended.
The rear-mounted throttle definitely does not work with SPI.
Adding a throttle ring would reduce top-end RPM, negating the SPI setup.
Would it lower the low-RPM? Dunno but doubt it. I think the higher pressure would actually force more air into the crankcase, further raising the low-RPM.
If one wants high power and a throttle it may be best to use a TD engine with a throttle ring.
Bernie
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Old 04-08-2011, 05:36 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Bernie,

Very interesting reading about your testing results in combination with SPI.

I use exactly the combination you posted last... "If one wants high power and a throttle it may be best to use a TD engine with a throttle ring."

For the sport flying 3-channel scale I have done this combination worked great. I could takeoff, do touch-and-goes, etc. with plenty of extra power available. I used 10% Cool Power fuel with no issues. It did not provide top RPM's, but I did not need the extra power and would rather save the engine life.

Other things we did in the setup was use 2-3 gaskets in the cylinder, do not use pressure tap and a piece of fule tubing over the needle valve to prevent leaking air.

Brian

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Old 04-08-2011, 07:24 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Brian,

Stay tuned for an OEM Cox R/C carburetor retrofit for TD 049 and 051 engines... ssshhh...

Bernie
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Old 04-09-2011, 07:13 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

      Next der muffler even tuned pipes wooot... = )~
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Old 04-16-2011, 04:40 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Any release date? Looking forward to this product.

Toshiro in Tokyo
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Old 04-18-2011, 08:25 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Toshiro,

The muffler project has been pushed back to after the Summer due to high capital cost investment.

Bernie

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Old 04-20-2011, 07:03 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Bernie, I did one of those retro-fit carbs years ago with an 074 queenbee carb , still runs sweetly but I may have to order one of yours for a back-up for future use just like I need to order a hand fupp of piston/cylinder kits and various other bitsyou offer that im low on my personal stock of lol

Thanks for helping keep our litle buggers running btw
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Old 04-29-2011, 10:55 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Well, I got one of the new cylinders, mainly out curiosity. Figured I could try one on the 05RC since they have no SPI.
They look rather strange in the bore to me, seems like they have been honed twice? The cylinder is very nice above the ports (if you put the piston in from the top) but around the ports and below they are very rough and the piston is also catching at the edges of the exhaust ports and remnants of twin exhaust ports. Are these re-machined in some way, or are they meant to be honed in two steps like this?

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Old 04-30-2011, 01:30 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Okey, I'm beginning to understand what I have now. Looks like it was a twin slit exhaust cylinder (just like the surestarts) where the center of the exhaust was removed. The lower part has then been de-burred with a regular stone, hence the coarse lines in the lower part of the bore while the top part still has a nice cross-hatched pattern. One of the ports needs some more deburring it seems. Is this really the new production cylinders?
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Old 04-30-2011, 07:20 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Mr Cox,

You are correct. They are the cylinders that had the dual slit with the 'bar' in the center removed. Any marks in the inside resulted from the need to remove any burrs. Some of them do look like they need to have additional de-burring done.

Matt.
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Old 04-30-2011, 07:41 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Okey, thanks for the info. Maybe that could be put on the website too. It might be a language problem I have, but when I read "Brand new current production item" next to an image of a cox #4 cylinder I do not expect to get a sure start cylinder. I thought the center bar shouldn't effect the performance anyway...

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Old 04-30-2011, 08:50 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Yes, you would have to talk to Bernie about the language in the listing. We bought these cylinders from him and are selling them in our own eBay store as well. Some potential customers expressed the same concerns about the language, and I'll make sure its updated in all of our ads.

Bernie is on vacation until the middle of May, but I'll make a note to let him know as well.

Matt.
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Old 04-30-2011, 06:06 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

Hello Zenalook!!,

I can't tell you how much I appreciate you firing up the old Cox line of engines!! In regards to the cylinders, I once purchased a Kustomkraftmanship engine (which I still have) and I believe it had a tapered cylinder. It really moves out!! Does this make a difference in engine performance? How hard is it to taper a cylinder?

Thanks again for all you have done!!

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Old 04-30-2011, 08:55 PM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

The "New" cylinders are more "tapered" from the deburring than the TD cylinders used to be....
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Old 05-01-2011, 11:10 AM
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Default RE: Cox Tee Dee 049 High Performance Cylinders

As I recall, with the original metalurgy of the piston and the cylinder, the hotter the engine got the tighter the fit became. Thus the taper was introduced to keep the bottom end friction down. My old speed engine I could drop a piston in from the top and it would drop through the cylinder when dry. How ever it takes a high RPM starter to start the engine. I think Bernie and his support group have the metalurgy better accounted for now.

George
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