What makes a 3.3 a 3.3

[Dodgeviperred]

Just out of curiosity what makes a 3.3 a 3.3 if the 2.5 has almost about all of same part?

[Double G]

3.3cc=.20 cubic inches
2.5cc=.15 cubic inches

[Wildman4910]

P/S are larger in diameter, larger P/S= more displacement.

[Wolfslash16]

2.5cc=.15 cubic inches

Wow, so does that mean the trx 2.5 and trx pro .15 are almost the same thing?

[DBG]

Wow, so does that mean the trx 2.5 and trx pro .15 are almost the same thing?

Yes, both have the same cc but the 2.5 have: "Straight-through Exhaust Flow" and that add more power because the .15 have like a L shape to the exhaust:

Picture(sorry for my fast drawing)




And another diference is the Connecting Rod. The edges of the connecting rod (2.5 engine) are knife-edged and that add more power too

Another difference is the The Powertune cooling head. The Powertune machined aluminum cooling head promotes even heat distribution for stable engine temps and rock-solid tuning consistency. Other mods include a new sleeve for improved engine efficiency and better power.

more info:

.15: http://traxxas.com/products/parts/engines/pro15
2.5/2.5r: http://traxxas.com/products/parts/engines/trx25


the diferences between the 2.5 and 3.3 are: look the Wildman4910 post

I hope this help

[trickydick]

I could be wrong but, I believe there are a lot of engine designs over the years, both 2 cycle and 4 cycle that made lots of power using the 90 deg. exhaust system, I believe 1 of the biggest differences between the .15 and 2.5/3.3 design has to do with the unigue piston design, 1 of only 4 engines I know of that were made with this unigue design, and the amount of heat trapping that occurs because of the large head clearances and also the failure to manage the needle setting that happens thru loss of head pressure in the fuel tank.
JM2CW