ox TD09 question

Welcome to the forum, FTID!

I suspect what you have is a pressure port. Tee Dees are often reputed as needing fuel pressure. I have no Tee Dees, so I can't answer regarding IF you need it...apparently somebody thought that engine did.

Regarding a muffler, I bought two for my .09 Medallions only to discover there are differences/combinations of mufflers/cylinders. My Medallions are closely related to your Tee Dees, so some of that may apply.

I know my Medallions use a different needle valve/spray bar that yours, so I won't go into how that may (not) apply to whether or not the different spraybars are a consideration for a throttled Tee Dee.

I recommend trying the engine as-is on a test stand with the pressure tap plugged (short fuel line with a bb or some other plug). Once you see how it runs, then consider trying it again with crankcase pressure. You will need to connect that pressure tap to one vent, and plug the other.

Also, look directly left...go below latest topics to the block INFO. Within INFO you should find the instruction sheet for a Tee Dee.
This may help: https://www.coxengineforum.com/t14906-td09-and-medallion-09-differences

TD instructions:

flytilidie wrote:Have acquired a TD09 but need help please .. My engine has a small hole at the base of the cylinder where it screws onto the crankcase , the hole is approx 1/16 diameter and has an insert of some kind fitted. The hole is on the right of the engine (viewed from the rear ) and is at 90 degrees to the crankshaft . There are also marks around the cylinder where possibly a silencer sleeve has been fitted . Never seen this before ,can someone identify if this is a standard Cox fitment or is this an external modification . Would like to send pictures but not sure how to do this ..

Also is there a source for new TD09 piston liners .... appreciate your advice  -- many thanks

If it is on the "base of the cylinder where it screws on the crankcase", what you described may have something to do with the positioning screw on the neck of the RC muffler, like on my photo below (which does not show the screw, only the hole) . The positioning screw is on at least 1 of my 2 RC mufflers on my 09 TeeDee-s, and when spanned, is supposed to fix the muffler and prevent it from rotating around the cylinder.

Many thanks for all your responses to my question , however the plot thickens !!!

so to answer some of the comments -- Galloping Ghoster , have checked my engine and at top dead centre i do have the bottom of the piston above the exhaust port - so yes my example does have the sub piston induction piston liner set .

balogh --- your picture is indeed illuminating and the locating screw position is in the same vacinity as the hole in the bottom of my cylinder head. On all my TD09s there is a machined groove 1mm above the bottom of the liner where it screws into the crankcase . The groove is approx 2mm wide and then the liner increase in diameter again till it reaches the start of the cooling fins . The hole in question is machined in the centre of this groove .  

So i have checked all my TD09s and they all have sub piston induction which makes them all original MK1 design engines . So do i conclude that my latest engine with this machined hole is actually a Mk1 design that has been modified to accept a silencer ( seems the only logical conclusion ) . And of course the tell tale marks around the cylinder obviously show something has been fitted to cover the exhaust ports .

Would i also be correct in assuming the MK1 version with sub piston induction has higher power output than the MK2 version designed to be fitted with a silencer ??  

hopefully i can post some pictures shortly but i really appreciate all your replies ,, great to have your help in solving this mystery for me ......

I think the MK -at least the MK2- refers to the .15 size TeeDee that had different bypass porting and only a single exhaust.

The TeeDee engines from 010 up to the 09 had the same porting design i.e. 2 bypass ports. The 049, 050RC and 051 also have additional booster ports, 2 per bypass port, that the 010, 020 and 09 do not have. (BTW on one of my 09 TeeDees-s I have also 2 boosters per bypass, that the previous owner cut, and this engine has way higher output than the stock 09 with bypass but no booster.....)

(https://www.coxengineforum.com/t10321-cox-teedee-09-cylinder-booster-ports?highlight=09+booster)

The .15 size MK has an improved Schnuerle type bypass, porting, totally different than the smaller TreDee-s. Also, cast iron piston and gudgeon pin instead of balljoint between the conrod and piston, that the smaller bro-s have.

Interesting...

When I got my pair of td09's, both with spi, had to get 2 new black plastic "inlet manifolds", which were easily available at the time ( mid 80's ).

These had the small tube stub on the rhs of the manifold but were " blind". I drilled out the stubs for tank pressurisation and they seemed to run much better, both powerfull engines for there size.

Mecoa stock them but will not send stuff to UK. I have the alloy versions which can be modified, but that's for this winter which is gunna be long and cold...

Got enya parts for exhaust and RC carbs, thanks for the info sosam...

I use all my TeeDee-s ranging from 010 to 09 in RC service, with atmospheric (i.e. non-pressurized) balloon tanks made from common party balloons, and have never observed fuel starvation due to insufficient suction capabilities, even though have never used the pressurization nipples.

I do not doubt pressurization can help if the engine starves and  runs lean, but I try to keep the tank near level with the engine and not too far.

Typical fuel line routes in my 09 powered SIG Wonder and Cosmic Wind RC planes (both 09-s but the one on the Wonder is further away from my phone camera and looks smaller):