So i want to build a 4 rotor rx7 and im newer to rotarys and want to know why rob dahms 4 rotor can do 2000hp and this budget one cant? Is it because rob is counting turbos and everything else and this other guy isn’t. Also does anyone know the engines rob took his major parts from? Here is the link to the budget one https://www.rx7club.com/old-school-o...-build-982977/

 

S4 irons aren't known to be the strongest, though thats mainly the rear, relatively high compression (not to mention heavy) rotors for boost, e-shaft is not a contiguous piece, the gears he made may or may not be hardened. Etc, etc.

 

would you recommend a different motor to start the build he states that the s4 engines with 4 rotor will practacly bolt right into a s3

 

I'd recommend doing it properly using known gears - unless you're versed in designing and making them yourself - and a single axial piece shaft with lobes added on. I'd also recommend using whatever irons are applicable for your situation such as how you're planning on mounting the engine, port configuration, and ower etc.