Most Rcs have a recommended limit on what type of motor to put in. ( like dont go beyond a 10T motor and the like)

I know i saw somewhere that there was a conversion when you speak in brushless like a 19 t = a 10t brushless.

where can i find this?

Typically those "limits" have to do with the speed control that comes with the vehicle or one you put in and nothing to do with the actual limits of what the vehicle can physically handle as far as power.

As to conversion formulas for brushed to brushless speeds. Novak has one on their site but I believe it's kind of out of date (unless they changed it).

Talking purely brushed to brushless in 6 cell or 2 cell lipo there are really only a couple of true comparisons to my knowledge (maybe somebody else will weigh in).

17.5 brushless = 27t brushed
13.5 brushless = 19t brushed

Now if you start getting in to different numbers of cells in a battery pack there are all kinds of comparisons to be made.

Typically those "limits" have to do with the speed control that comes with the vehicle or one you put in and nothing to do with the actual limits of what the vehicle can physically handle as far as power.

As to conversion formulas for brushed to brushless speeds. Novak has one on their site but I believe it's kind of out of date (unless they changed it).

Talking purely brushed to brushless in 6 cell or 2 cell lipo there are really only a couple of true comparisons to my knowledge (maybe somebody else will weigh in).

17.5 brushless = 27t brushed
13.5 brushless = 19t brushed

Now if you start getting in to different numbers of cells in a battery pack there are all kinds of comparisons to be made.

The only other thing I can add is that at our dirt oval track we have found that a 10.5 is just a little quicker than a 12 turn. If someone has more info, I would like to know also.

I had a fairly good formula figured out for the old bonded-rotor motors, but the sintered rotors totally changed things and I haven't gotten any meaningful dyno numbers since. (And most of the brushed motors I compared to are getting old!)

My personal wild guess would be something like:
10.5 BL = 14-15 turn brushed
8.5 BL = 12 turn brushed
6.5 BL = 10 turn
5.5 BL = 8 turn
(below this point, brushed motor equivalents become meaningless, so....)
4.5 BL = Chevy 350
3.5 BL = Space Sshuttle solid rocket booster
2.5 BL = Starship Enterprise warp engine

Dont Forget About The 0.5 Turn Brushless Thats Coming Out In 2010 Called The Flash Of Light....