Cox Model Engine - The Engines - Tee Dees

Tee Dees

• 1961 Tee Dee 049 (Cat#170 - Manufactured Nov 1960-Jan 1996)

This is without a doubt, Cox's greatest and most famous engine. This engine was "THE" engine to use in competition for many years. It was designed by Bill Atwood who had been hired by Cox specifically to produce the Tee Dee line of competition engines. The important features of the Tee Dee are as follows:

• Tapered cylinder and a lightened and tapered piston
  • Result: tighter piston fit at TDC and less piston mass = more performance.
• Two deep bypass ports with two bypass booster grooves on each bypass port, extending slightly above the main bypass groove
  • Result: significantly better air fuel mixture induction = more performance
• True peripheral venturi
  • Result: more efficient fuel intake, fuel draw and induction = more performance
• Precision balanced and milled crankshaft
  • Result: better fuel intake, better balanced engine = more performance

The Tee Dee was tested by Aeromodeller Magazine in 1962 and the output power was recorded to be .105 bhp (78 watts) @ 22,000 rpm with a max torque of 5.5 oz.in. at 18,000 rpm on 25% Nitro. (Note: The modern Norvel AME 049 engine which has an aluminum piston running in a ceramic coated cylinder, outputs .14 bhp (100 watts)@ 20,000 rpm). In 1973 the bypass porting, crank shaft timing and venturi were modified slightly and a mesh screen was added to the venturi to keep out dirt. This resulted in a minor performance improvement over the earlier versions.

• 1961 Tee Dee 051 (Cat#200 - Manufactured Oct 1961-Jan 1996)

The 051 was simply a Class A version of the engine, physically the same on the outside only the bore was different and the piston had a small groove in the skirt to differentiate it from the 049. The 051 also had a RED carb body.

• 1994 Tee Dee .05 RC (Cat#201 - Manufactured 1994)

This engine had a proper RC carby and a full sized standard muffler and was designed specifically for RC flying. It had no Sub Piston Induction. Only two production runs of 1000 each were done so there are only 2000 of these in existence, making them the second rarest production engine next to the Venom. Note: Although the box said Tee Dee .05 the engine is actually .051

An .09 RC version also exists (Cat# 211 - Manufactured 1994 also)

• 1961 Tee Dee .010, .020, .09 & .15

Cox also built Tee Dee's in .010 (Cat#130), .020 (Cat#160), .09 (Cat#210) and .15 (Cat#180) size. All these engines were very successful.

A little known fact was also this: One of the things Cox wanted Atwood to do was make him a .010 engine. Cox had already tried to halve the size of the Pee Wee .020 but couldn't get it to run for some reason. The suspicion surrounded a problem with the tiny reed valve. Atwood found that the front rotary valve worked well on the .010 size hence the .010 was born. Why? Because Leroy Cox wanted one.