plz list the sizes from most powerful to least powerful 2.5, .18,.12,etc.etc.

in 1/10 scale its basicly .18 .15 .12 but some 1/10 scale have conversion kits for .21 and there are a lot more powerful engines bit too many to list and the 2.5 is a .15

some monster trucks come with .21

some high quality .12's are more powerful than some .15's

is it posible to put a .21 in a RC10GT?

with a conversion kit from new era models (i think thats who make it )

do you have a link?

www.neweramodels.com