Why do some 2nd gen rx-7's have dual exhausts, but the FD's only have single? What was mazda's reasoning for either?

Just curious.

 

Like many other choices for the car: weight. One 3" pipe flows more and is much lighter than two 2" pipes. Those aren't the exact sizes of anything in particular, but they help illustrate the point. There is no need for dual exhaust since the exhaust is collected before the turbo anyway.

 

The 2nd gen has a small pipe running from engine to the cats and then a small pipe running from the cats to the split in the exaust. The dual exaust is just for looks does not really improve any air flow.

 

Dual exhausts make sense for large V piston engines like the Ford 302, or Chevy 351. They don't quite make sense for the rotaries unless each rotor got it's own exhaust tract, which I believe is NOT the way Mazda built the 2nd gens. And it would make absolutely no sense on a turbo equipped rotary since both rotors spin the turbo(s) together.

 

curious...I know the RX-8 or evolve are concept cars but aren't they showcased with dual exhausts as well, i believe they had a valid reason as posted in a magazine before.