standardbyker88
+1y
they are a powerful option if done with a turbo. many came stock that way. also, the older ones are carbed and even less powerful. the 13b came in the rx7s, but also in a lot of other mazda vehicles. wiki will list what all. fairly plentiful motor. they dont have piston rings, they have rotor "rings". stock ones were known to wear out a lot, but properly tuned FI and aftermarket "rings" they can be fairly good to go. i was seriously considering it for my yota. id like to use one someday in something. a mid-rear setup would be sweet.
they also do rev up to 7k stock. they have limiters to prevent going higher. they work on the process of a rounded triangle on a "spyrograph" style shaft. it sucks air/fuel in, compresses it, ignites it and exhausts it. still 4 cycles. only its in a big u turn. not in in/down/up/down/up/out setup. lightweight engines. simple. but, can be a bit finicky sometimes.
do some research. ask yourself if you like doing engine stuff yourself. consider the power gain against the rear ends that can take it and fit between your bedsides. then, if you like the idea, do it.