What is the difference between these?
 

How can I visually tell the Traxxas 2.5 engine from the 2.5 R (revo) engine?
And what is the difference in terms of performance?

RE: What is the difference between these?
 

I know on my friends 2.5R there is a huge R next to the 2.5 on the side of the engine.... I'd assume the non-racing 2.5 engine wouldn't have this.

RE: What is the difference between these?
 

The 2.5 has a silver head and the 2.5R race engine has a blue power tune head also the 2.5R has a different sleeve.The nitro rustler comes with the 2.5 Race Engine (silver head) The 2.5R is an up grade. I hope this helps ya out.

RE: What is the difference between these?
 

Piney, can I upgrade my 2.5 by installing the 2.5R sleeve, or does it not fit?

RE: What is the difference between these?
 

No I don't think you can the piston rod and sleeve are different you go to to your lhs and trade your 2.5 in for the 2.5r it's $100.00 and you get a new 2.5R Race Engine or you can ship it to traxxas and do the same thing. Look at Traxxas .com for the life time engine replacement .I had the 2.5 and traded up for the 2.5R Race Engine and it just drops in and you can use your easy start with it or the pull start like I did I didn't like the easy start because it was difficult to get to the LSN and it added extra weight. But you can do what ever is easier and works better for you. :D:D

RE: What is the difference between these?
 

Yeah you can switch the sleeve and piston from a 2.5r to a 2.5. There isnt much of a differene beside the apperance of the heat sink. Infact they dont even make 2.5's any more from what I have heard. The only difference from the 2.5 to the 2.5r is the port's shape and the port timing of the engine. Thats the only real power difference between the two, you can easily switch between the two and they should fit.

As said they will fit the only real difference between the two is the apperance of the heat sink and some little port mods that traxxas made. But if you want to buy a new engine then look at O.S, there better then the Traxxas engine's in many ways. There more reliable, easier to tune and hold there tune for forever, and a .18cvr makes way more power then the 2.5 does. But you will have to do some mods to make it fit on the truck that you have,but I think the mods would be well worth it and it only cost's $99 on towers the last time I checked. Or you can get the .18TM also made by O.S and that is able to use the ez-start. The TM is as powerfull as the 3.3 is.