How to compare gasengine size to outrunner ?

[What's_nitro?]

I'd definitely go 8s with the 1521/1y. Lots more torque at the wheels with that gearing. Speedy, those motors are nice and they will get the job done, but they are $65 for a reason. If they get pushed too hard they pop, fizz, etc. You should save your money and get better stuff because you'll be happier in the end. On the other hand, try the outrunner. If it blows up then w/e- it was cheap!