Re: Tee Dee Performance Crank

**Cribbs74** Sun Apr 12, 2015 10:51 pm

That thing is pretty snappy! It's hard to see it pass by, you have to watch closely.

Couple questions, Why the KB setup? The stock TD P/C is the same or similar to the KB. Second question is how many head gaskets?

I'll forget that I saw the starter motor... Wink

1/2A Nut Mon Apr 13, 2015 1:54 am

The number 1 reason is the piston back in the day (in my case engine No. 340- May 1995) came with a lightweight piston, the ones today are not. Having that piston lighter than stock makes a big difference no other engine has this effort done. Bernie should sell optional lightweight pistons for folks who want to hop up their engines. Small Cox Logo

Other attributes:

- cylinder / piston is tapered and matched
- inside of the cylinder has been polished (KB's are the only ones I have ever seen mirror finish)
- cylinder has max deep cut dual by pass ports
- cylinder has dual flutes
- SPI
- dual slit exhaust causes ejection of exhaust goo further out away from the fuselage.
(other than that it is robbing some power I would like single exhaust ports)

Just look at the rpm numbers for the break in run and the second break in run no pressure bladder and numbers obtained using a more restrictive RC carb.

Surfer_kris Mon Apr 13, 2015 3:53 am

1/2A Nut wrote:Bernie should sell optional lightweight pistons for folks who want to hop up their engines.

Well they used to sell that (see below), I haven't checked lately though.

How does your rpm numbers compare to a stock TD on the same props?

Tee Dee Performance Crank - Page 10 Cox%20049%20Sub%20Induction%20Cylinder%20%26%20Piston%20-%20SPI%202

Tee Dee Performance Crank - Page 10 Cox%20049%20Sub%20Induction%20Cylinder%20%26%20Piston%20-%20SPI%202

1/2A Nut Mon Apr 13, 2015 4:11 am

That's good news perhaps Bernie will have a new batch made up. I have not seen them sold currently.
The KB has a full copper lining inside the piston and of course its a tapered type.

The Killer TD .049:
I am breaking in the engine in the air per second flight
APC 4.5 x 4
22,044 rpm in the hand 25% nitro
best pass at 24,160 rpm needle is set bit rich.
67 deg. winds 6 to 9mph
After a few more runs I expect a fully broken in engine getting about 25k needle peaked.

Previous engine used a TD .049 - peaked out engine that's already broken in.
Dual bipass ports no apparent flutes - slight SPI function less than the KB
APC 4.75 x 4 (no data with the 4.5 x 4)
19,380 rpm in the hand 25% nitro
21.4k to 23.3k rpm in the air dependent on direction.
Winds about 4 to 6 mph per hourly weather check. 74 F.

This is the only data thus far will run the engine a few more times a bit rich to insure its broken in best it can be and will then run a 4.75 x 4 to compare.

balogh Mon Apr 13, 2015 4:18 am

Bernie sells the shortened piston with double slit cylinder, but only in his Pink Panther engine, not in a separate set.I had this set before and it was really a high performer. I am not sure if my separate set, - not purchased in a genuine Killer Bee but probably made by the aftermarket - had tapered bore.

The TD049 that revved a bit slower was a non-SPI?

getback Mon Apr 13, 2015 7:30 am

Good Job 1/2a nut you are doing some Great mods. that seem to be paying off for you . Here is a link some time back that has some good info on it for shorting and lighting pistons .. https://www.coxengineforum.com/t3169-shortening-and-lightening-a-piston?highlight=piston+lightening#top I am hoping to try this soon I have some extras now for experimenting . Eric Cant Resist The Bunn

fit90 Mon Apr 13, 2015 10:42 am

1/2A Nut,

You should try one of Bermie's Tee Dee starter springs. Just drill and tap a hole for a #2 bolt where the pressure nipple is on the plastic venturi body, install a #2 bolt with red Loctite, cut the bolt head off and install the spring. The springs work great and will probably greatly increase the longevity of your engine. Also, I have purchased piston/cylinder kits from Reggie at VGE and he has lightened the pistons for me.

**Cribbs74** Mon Apr 13, 2015 10:55 am

1/2A Nut wrote: The number 1 reason is the piston back in the day (in my case engine No. 340- May 1995) came with a lightweight piston, the ones today are not. Having that piston lighter than stock makes a big difference no other engine has this effort done. Bernie should sell optional lightweight pistons for folks who want to hop up their engines.

Other attributes:

- cylinder / piston is tapered and matched
- inside of the cylinder has been polished (KB's are the only ones I have ever seen mirror finish)
- cylinder has max deep cut dual by pass ports
- cylinder has dual flutes
- SPI
- dual slit exhaust causes ejection of exhaust goo further out away from the fuselage.
(other than that it is robbing some power I would like single exhaust ports)

Just look at the rpm numbers for the break in run and the second break in run no pressure bladder and numbers obtained using a more restrictive RC carb.

Thanks for the info, I thought I read somewhere that the TD P/C sets were tapered with a lightened piston as well. I do know that the Venom uses a TD set and it has a lightened piston.

I took a look at the engine test report on a TD and it looks like peak torque is around 18K and peak HP is around 22K. That is for a CL version though.

I am not sure what works best for you as an RC flier, I prop for torque as a CL stunt flyer. Just something to keep in mind as you test and tune.

It's an impressive little plane no matter how you slice it!

Ron

crankbndr Mon Apr 13, 2015 11:36 am

I did some checking a while back
https://www.coxengineforum.com/t3649-piston-weight?highlight=piston+weights

Tee Dee Performance Crank - Page 10 Pw_tif10

balogh Mon Apr 13, 2015 12:25 pm

balogh wrote:Bernie sells the shortened piston with double slit cylinder, but only in his Pink Panther engine, not in a separate set.I had this set before and it was really a high performer. I am not sure if my separate set, - not purchased in a genuine Killer Bee but probably made by the aftermarket - had tapered bore.

The TD049 that revved a bit slower was a non-SPI?

Thanks to this thread I got intrigued and fished thru my spares box, then found these 2 brand new sets, the pistons are shortened, one of the cylinder came with a number 7 mark, the other is unmarked, and both are double slit exhaust, with 2 bypass ports and 1 booster flute on each side.

Tee Dee Performance Crank - Page 10 Shortp10

You may find me a prodigal son just sitting on valuable spares not even being aware of what unique parts I have in my possession, but I may have bought them from Bernie years ago (actually 3 sets, one is already in a used Surestart) when I had no TD-s yet and I did everything possible to bring out max power from the Surestarts I then had on my R/C planes.... and they went into oblivion once I fell in love with TD-s and continued running only these guys .

Now here is the thing: the double slit cylinders are all non-SPI with normal pistons, but the short pistons turn them into SPI.

With a TD SPI cylinder that I have on stock, the short piston may open up just too much of a gap at TDC under the piston skirt which may then be off-optimum. I read somewhere here that excessive SPI may kill the SPI benefit by allowing too much air into the crankcase and even if with a wider open NV the fuel-air ratio can be theoretically set, the mixing of SPI-air with the air-fuel mixture that comes the normal way through the venturi, nicely pre-mixed, will not result in the same uniform mixture.

But this may simply be the over-theorizing of how SPI works. Fact is what 1/2A Nut found, i.e. the marriage of a TD cylinder with a short piston will result in extra power compared to a TD.

I will try the short piston with a new TD cylinder (stepped wall, probably tapered, bought on ebay) and check the difference with my normal TD049 ...I expect the same results as 1/2A Nut reported above.

crankbndr Mon Apr 13, 2015 12:44 pm

I ran the surestart cyl. with the lightened piston combo in the Unlimited class in the Tach Race this year.
Kim got it to 23.1 K but it finished in the third spot.

Tee Dee Performance Crank - Page 10 Tach_r10

1/2A Nut Mon Apr 13, 2015 2:31 pm

The TD .049 has a slight SPI function not as much as the KB or other TD's that I have.

The weight difference I noted with a calibrated digital scale was KB .049 2.8g vs TD .049 3.3g I only remember for sure there was a .5g difference.

Doug did your engine use a mylar reed or the original brass reed?

I am using 3 shims on the Galbreath / Nelson head for the 4.5D prop.

Great additional info guys good reading!

On the prop comment vs max torque I am wanting speed so give up some thrust for additional rpm
I would say the ideal prop for speed to be on the peak torque range would be a 4 x 5

The APC 4.75 x 4 combat prop performs very well the down side is the hub is bigger the 4.5 x 5 has a hub that matches the TD prop plate.

1/2A Nut Mon Apr 13, 2015 8:45 pm

Found this comment from Bernie:

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
www.coxinternational.ca

1/2A Nut Mon Apr 20, 2015 3:09 am

Ok have an update from this weekend I flew break in flight #3 I will inject the info between the previous data.
I decided to step back to the 4.75 x 4 as I have data with the TD .049 to compare.

The Killer TD .049 - Cox RC carb
I am breaking in the engine in the air
2nd flight APC 4.5 x 4
22,044 rpm in the hand 25% nitro
best pass at 24,160 rpm needle is set bit rich.
67 F. winds 6 to 9 mph
After a few more runs I expect a fully broken in engine getting about 25k needle peaked.

3rd flight APC 4.75 x 4 - Galbreath / Nelson plug
20,873 rpm in the hand 25% nitro
22,287 rpm cross wind and 23.94k down wind
9 to 12 mph winds - temp 78 F Humidity 80%

Previous TD .049 - Cox RC carb - Cox High Comp plug
APC 4.75 x 4 (no data with the 4.5 x 4)
19,380 rpm in the hand 25% nitro
21.4k rpm cross wind 23.3k down wind.
Winds about 4 to 6 mph per hourly weather check. 74 F.

Looks like the new Killer TD is winning the race static on the 4.75D is up 1,493 rpm
- in the air on Sunday with that prop up to 91 mph theoretical. Down wind it was Skorchin,
into the wind it cuts through very well. The design has no issues with wind the wing is a
1/2 A razor blade. The power to weight is great for a 5 ch plane and it will hang on the 4.75 prop
The large rudder has authority to hover with throttle management if allowed there is just enough
to slowly climb to max viewing height. It will hold a knife edge into the wind but gets pushed
down wind so I enter nose up and then bang in full rudder to make a full down wind field pass.
No elevator input is needed it doesn't pull away either direction speed is the key to riding on
this ply rolled fuselage!

Flying

1/2A Nut Wed Apr 22, 2015 10:51 am

Will be trying this set up next with one of my TD performance cranks. I took a non SPI TD RC .051 piston / cylinder set and with the buggy exhaust pipe I have about 1" additional header worth trying as is and then go from there.
Nice tight seal no leaks the dirty part is I went from a round header to a square section not ideal but it's a start and its a straight shot to the cylinder big plus I will fabricate something cleaner. The plan is to cut down the square exhaust tube to the hilt and drill tap two hold down grub screws to fix a round tube adapter with enough length to use with a silicone coupler. The Tarno RC carb may handle more forced draw from the pipe than the Cox RC carb so will give it a twirl.
Pipe is a Profi 1/2A.

Tee Dee Performance Crank - Page 10 Td_tun10

1/2A Nut Wed Apr 22, 2015 10:59 am

Here is a rendering with it tacked on the back of the Skorch - pipe weight is 11.3g Thumbs Up

I have sourced 1/2A pipes for $55 ea.
New PROFI Rambler .8cc tuned pipes

ALBERTO CABALLERO, FLA / USA
Ebay contact; speeddomingoe

Tee Dee Performance Crank - Page 10 Imag0610

1/2A Nut Wed Apr 22, 2015 11:04 am

I can see the pipe on der Skorch's back now Easter Bunny

Tee Dee Performance Crank - Page 10 Imag0611

1/2A Nut Wed Apr 22, 2015 11:06 am

Note the length is a hair bit under 9in . / 9.6mm OD up front and the stinger ended up at 6.8 mm OD

Tee Dee Performance Crank - Page 10 Td_tun11

1/2A Nut Thu Apr 23, 2015 12:56 am

Holy sheep shank the Lil pipe that could..

APC 4.5 x 4
Tonight I tested with crank case pressure it was running rich on purpose reading 18,760 at full throttle after about 5 seconds
it jumped up on the pipe and accelerated an additional 3,260 rpm.
This engine is being broke in as it is a rare .050 / cylinder non SPI so being gentle just wanted to see / hear the pipe work. Eyebrows

The pressure built up fast and the pipe blew off after 20 seconds or so - only had 1 zip tie on the pipe side.
I have ordered a 7mm ID silicone coupler long enough to get a solid grip on the pipe will need two zip ties.
The pipe coupler will be from a 1/10th scale silicone exhaust deflector for cars small as they come at 7mm ID
I will cut the long end off and rough up the pipe some for better grip.
One thing I noticed it idled very well not very low 9,070 rpm but steady.

Tee Dee Performance Crank - Page 10 Imag0612

Tee Dee Performance Crank - Page 10 _12oiu10

balogh Thu Apr 23, 2015 1:08 am

1/2A Nut, this is a very interesting exercise...unfortunately I could not find the tuned pipe on ebay yet. Where did you get that and the exhaust muffler to which you plan to attach the pipe?

Thanks.

Oldenginerod Thu Apr 23, 2015 6:48 am

crankbndr wrote:I ran the surestart cyl. with the lightened piston combo in the Unlimited class in the Tach Race this year.
Kim got it to 23.1 K but it finished in the third spot.

Sorry, coming in on this conversation a little late, but it may be worth noting that my winning mouse engine (24,100 rpm) ran a standard (used) piston in a new "Tee Dee" clone cylinder from Bernie. That's a Surestart cylinder with the exhaust port bars removed and lower edge machined to induce SPI. Standard Tee Dee head. No other tricks. Not sure it's the light piston that makes the difference, but current lightened pistons are also shortened to induce SPI with a standard non-SPI exhaust port. They wouldn't work in this cylinder as it would create double the SPI.

Rod.

1/2A Nut Thu Apr 23, 2015 9:23 am

http://www.ebay.com/usr/speeddomingoe?_trksid=p2047675.l2559

Alberto's page message him for pipes he wants $55 plus shipping.

Rob note the prop I am spinning.

The Killer TD .049 - Cox RC carb
I am breaking in the engine in the air
2nd flight APC 4.5 x 4
22,044 rpm in the hand 25% nitro
best pass at 24,160 rpm needle is set bit rich.
67 F. winds 6 to 9 mph
After a few more runs I expect a fully broken in engine getting about 25k needle peaked.

1/2A Nut Fri Apr 24, 2015 4:37 am

Odd that I have just been running a real great engine on the Skorch I would be removing the Killer TD piston and cylinder lol but must make way for the tuned pipe.
So I have the RC.050 piston / cylinder with the performance crank and the Cox carb with rear back plate KK pressure tap.
I bought some small Robart 1/16th pressure type T couplers so I can spot when the tank is full and avoid flooding the crank case.

I will use a TD high compression glow plug to start I may have to slap on a standard plug if the rpm's are excessive.
Will tach the engine Friday and see what the static reads are and the CG is gooood whew the mass of the silicone coupler
helped offset the rearward pipe weight. Decided to park the pipe to the side for a few good reasons to divert goo from the tail
level the pipe to avoid oil build up and to offset torque roll on launch.

All up weight is 12.46oz not bad for a 5ch 1/2A plane with a tuned pipe!

Tee Dee Performance Crank - Page 10 Imag0615

Tee Dee Performance Crank - Page 10 Imag0613

Tee Dee Performance Crank - Page 10 Imag0614

**RknRusty** Fri Apr 24, 2015 10:46 am

That is so slick! It sure would look good in my fleet. I know nothing of tuned pipes other than the reflective wave action... I believe I'm using the right term. Resonance, basically. In stunt planes the desired performance result is much different than in a speed plane.
Rusty

balogh Fri Apr 24, 2015 11:38 am

1/2A Nut wrote:Odd that I have just been running a real great engine on the Skorch I would be removing the Killer TD piston and cylinder lol but must make way for the tuned pipe.
So I have the RC.050 piston / cylinder with the performance crank and the Cox carb with rear back plate KK pressure tap.
I bought some small Robart 1/16th pressure type T couplers so I can spot when the tank is full and avoid flooding the crank case.

I will use a TD high compression glow plug to start I may have to slap on a standard plug if the rpm's are excessive.
Will tach the engine Friday and see what the static reads are and the CG is gooood whew the mass of the silicone coupler
helped offset the rearward pipe weight. Decided to park the pipe to the side for a few good reasons to divert goo from the tail
level the pipe to avoid oil build up and to offset torque roll on launch.

All up weight is 12.46oz not bad for a 5ch 1/2A plane with a tuned pipe!

[/

This plane is just gorgeous and I wish I only had the luxury problem of getting the goo on the tail.. .mine still resonates, probably the wing fixture to the saddle is loose, and it weighs 15 oz even without a pipe...though fast enough.

Sponsored content