Some td 0,49 questions

The prop screw on a TD 049/051 is a 5-40 x 1". The 5-40 thread is the same as on the reed valve engines, but as Ron stated the length is longer to accommodate the spinner. The length of a typical reed valve screw varies from 1/2"" to 3/4" depending upon the type of driveplate installed and individual configuration.

From backplate to end of driveplate is 1 11/16" long.

Best Regards, Matt

Hey cribbs74 and ExmodelEngines,

thank you very much for this informations and the considerably database.

I needed this informations for an mhh... I like to say addlebrained project .

EXModelEngines wrote:From backplate to end of driveplate is 1 11/16" long.

Or approximately 43mm, for our europäischen Freunde.

[quote="ahrma_581"]

EXModelEngines wrote:From backplate to end of driveplate is 1 11/16" long.

Or approximately 43mm, for our europäischen Freunde.[/quote

Another question. Does a cylinder and piston of a reed engine fit on the crank and crankcase ?

I think it's possible to fit cylinder from a Tee Dee on a reed engine, so the reverse way is also good.

Thats what I want to hear, thank you .

I was not sure.

Yes, the thread is the same for a reed valve vs. a Tee Dee. I would caution that putting a Babe Bee cylinder/piston on a Tee Dee will decrease power, even though it will fit.

Matt

Just be aware that even though it's possible. Unless it's a #4 cylinder the performance will decrease some.

Oh yes thats to consider.

What do you think = will a td 0.49 fitted with a normal bee style cylinder have more power than a ,,normal'' baby bee?

I think one of the reasons a td is more powerful than a reed type engine is the rotary valve intake or is this wrong?

I know it is not so easy to compare = The interaction between intake and cylinder has to be respected too.

But if it is so ( a slight increase of highest rpm) it would be a great sucess for my project.

You can only force so much fuel/air into a single port cylinder. So it may hamper it considerably. I guess you can try it and see. You can get a #4 pretty easily also at the very least maybe you can use a #1 or a surestart cylinder.

Is the #2 cylinder your only option?

Ron

cribbs74 wrote:You can only force so much fuel/air into a single port cylinder. So it may hamper it considerably. I guess you can try it and see. You can get a #4 pretty easily also at the very least maybe you can use a #1 or a surestart cylinder.

Is the #2 cylinder your only option?

Ron

Good going, Cribbs. You've become a good engine guy. I've seen several of your replies lately with very good insight into engine operation.

coxaddicted wrote:...I think one of the reasons a td is more powerful than a reed type engine is the rotary valve intake or is this wrong?...

That's right. One of the other benefits is the aggressive porting of the #4 cylinder. And the large venturi, through which the flow isn't inhibited by the wasted energy it takes to suck open a reed. And on a tanked engine, there's also the long run through the venturi tube as an added restriction. Some mousers may disagree with that last point.

Hi Ron and Rusty,

thanks for your comments. It was just a general question regarding the cylinder.

The cylinder i would like to use is this one:http://www.exmodelengines.com/cox-.049-medallion-cylinder-piston.html

The reason for this cylinder choice is a muffler with throttle (which fits only with the ground cylinder)

The reason for the questions is, that i am not owning a td 0.49 yet. For me, it would only make sense to buy one if it will fit this ,,ground cylinder''.

I will look for a td 0.49 now and see if it will work.

Who'd have thunk it, I would like to ,,implate'' the td in my kyosho cox car

Thank you for your assistance guys

Ups,

the description says the cylinder does not fit on td`s but on medaillion.

I think I have to go deeper into this ,,dark matter'' of rotary valve engines.

That description is only a performance issue, it will "fit." The Tee Dee and Medallion share the same crankcase, but the Tee Dee is a much higher performance engine. For your purposes any cylinder that will screw into one will screw into the other. The stock Medallion cylinder is considerably lower performance than a Tee Dee #4, but the one you are looking at is non-spi, which is the right one if you use a muffler or an exhaust restrictor type throttle.

Just to clear up a little confusion with that ground cylinder. These were factory ground and fit the older throttle sleeves.

All of the other cylinders we sell will work with the throttle sleeve we sell here:

http://www.exmodelengines.com/cox-.049-throttle-ring.html

This is not to say the throttle sleeve will not work with it, but it will be a little looser.

If you want to you for performance I would recommend this piston/cylinder. This basically equates to the cylinder/piston of a post 1996 TD. You can use a throttle sleeve on it if you would like:

http://www.exmodelengines.com/cox-.049-cylinder-piston-high-performance.html

Matt

Matt, would he be better off with a non spi cylinder and the throttle ring, or does it not have the same issue with gulping exhaust gas at TDC as with a muffler. Forgive the dumb questions, I've never used a throttle ring so I don't know much about it.

RknRusty wrote:Matt, would he be better off with a non spi cylinder and the throttle ring, or does it not have the same issue with gulping exhaust gas at TDC as with a muffler. Forgive the dumb questions, I've never used a throttle ring so I don't know much about it.

I often wondered that myself.
Sub parr performance using a muffler with spi has always been a given, but
what about r/c throttle mufflers and rings?
I'll give it hell and maybe do a comparison test this weekend. (Emphasis on the maybe).
Bob

RknRusty wrote:Matt, would he be better off with a non spi cylinder and the throttle ring, or does it not have the same issue with gulping exhaust gas at TDC as with a muffler. Forgive the dumb questions, I've never used a throttle ring so I don't know much about it.

In the tests that I have done, using a SPI cylinder with a throttle ring did not have nearly the affect that using one with a muffler did. Then again, I only tested this very very little on reed valve engines with a Black Widow cylinder (has SPI). Testing side by side of SPI vs Non-SPI with the throttle sleeve would probably be good to quantify results.

I tend to prefer the throttle control on the carburetor unit for the TD style engines and the throttle ring for reed valve because you do loose a little power with the throttle ring. Again, everybody has their own setup they like, and sometimes these little engines have a mind of their own!

Matt

The first few iterations of the Killer B'stard in the Old timer had spi and throttle ring.
If memory serves it held 18.5 dropped to 7, was 'sweet as' anywhere in between
with instant pickup/better than the TD09rc even.

I think this probably answers a few of the previous questions.....
Again if memory serves this was just before first cox 'powered' flight
running on some really sh/not very good (ie water infused) 15% .