can i put the .21 engine on the volcano stx and use the same spur gears and use different ones i am new at this

The spur gears will be fine.

you CAN install the .21 into the Volcano...but it's a LOT of work. you'd be better off buying an OS .18CVR-X (standard crank/rotary carb) for your truck.

or LRP'S .18 motor is awesome too

Actually the 18CVR makes more power if the LRP .18 is the version of the SH .18 that I think it is...

i dont know, os does make awesome motors but i was really impressed with LRPs offerings and the price is right for them. heres a link for some more info on the motor,
http://www.teamassociated.com/shusti...rp/engines.htm

What about going with a 4 stroke motor?
[link=http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJRW8&P=7]4 Stroke .26[/link]

Lots of low end power. They're quieter. Easier to start. Better fuel economy. Other than that I really don't know the benefits and cons of a 4 stroke motor.
What do you all think?

iv never seen anyone put one in an rc car i think they are mainly for planes, i dont think a .26 will work in a 10th scale without a conversion kit, which nobody is curently making for himoto or redcat products, but i dont know i could be wrong.

That particular model right there says it's made for 1/10 scale touring cars. so it should fit with very little modification. You'd have to change the positioning of the throttle servo possibly but other than that I don't think it'd need much more modification.

it says .5 hp LOL so i don't think i'd be worth it.
ugly lil motor.

Think of it more like a diesel engine. Lots of torque. Not as much h.p.
That means it could spin a bigger gear compared to a 2 stroke.
This thing mated to a 2 speed would be killer. Put the right gears on and it'd have amazing acceleration and then once you got going you could throw a huge gear in for 2nd and watch the thing fly.

tourq IS good but there is no substitution for hp

the 4 stroke RC Car engine has a lot of potential...but IMO he'd actually be better off with a traditional 2 stroke engine, because it takes a LOT of time, work, and money to make a 4 stroke .26 run with a halfway decent .12 or .15. He'd wind up with $400 into the engine, not to mention it has to be converted to a standard long crank to be used in the 1/10 Redcats.

BTW-with an OS .90FS muffler and a ported head, they're no quieter than a race bred big block in a 1/8 buggy...they're frickin LOUD (with that muffler)....not that that's a bad thing