can anyone tell me what is the best/biggest engine upgrade for the Jato that doesn't require any mods

os .18tz, os .12tz

without any mods, probably just the 3.3, the only small block that really has it beat is the os tz(that iv seen).
any.21 you put in it will take a big block conversion kit, the .18tz will take some modding of the servo linkage unless you get the slide carb version then it might be a direct fit im not sure.

the .18tz will drop in, the eb mod .18 tz does not, it takes some modding..

the .12tz could probably take the 3.3

I've installed an .18 tz eb modded in a jato 3.3 there are some minor mods we made we put the engine mount spacers on the top of the engine side so the motor sits lower. We also cut the shaft so we could use a bolt in the end with a washer. Lets just say were very happy with the setup no motor problems at all!!!! now on its 3rd gallon with the same cb bearings that same nut and washer holding the clutch bell bearings on. Havent stripped any spur gears and by putting the engine lower it will improve the handling.


http://youtube.com/watch?v=5uSKBTfF444