which of the o.s engines is the fastest of all?
what is the top speed it may reach with decent garing on an hpi mt?

Well, the os 18's are for torch and the 12's I believe are for more speed, they rev at higher rpm's.

if you gear an 18 it will have a higher top speed, but 12s are much faster all round, because of the revs.

Dann

In a truck with the same gearing, the .12 have a faster top speed then the .18 because it can reach higher rpms. But the .18 would have alot more torque and acceleration.

In your MT, you would like the .18 better because it has the low end torque to pull the 4x4 and it has the hp to pull higher gearing so you can get the top speed you want.

So I guess what I'm trying to say is the .12 would be best and fastest in a 2wd stadium truck, but the .18 would be best in your truck. Thats what I'm running in my MT2 and I absolutely love it.

those new o.s. .12's are insane! and expensive!

If you want the baddest MT around, get the OS.18 TZ, but be ready to fix drivetrain parts

I would use a .12 cv or cv-r in just about anything except for a heavy 4x4.