The weight figure for a 13bto vs ca18det shows clearly the Ca is much lighter.
151kg for the 13b NA (not turbo) vs 128kg for ca18det.
These weights are confirmed by rotary enthusiast on www.rx7club.com so allowing
50lbs 22kgs for turbo gear 13bt guise its 173kg.
The only lighweight 13b is an NA built with alloy rotor housings, minimal thin
hand carved inlet manifold and custom thin walled inconel exhaust header.
Without the header the Racebeat 13 NA is 96kg without clutch and flywheel with
electric waterpump and alloy endplate housings instead of cast iron.

If they werent expensive, uneconomical, hard to register and with ally endplates
in Victoria I would not hesitate. But the fact is they are now for deep pockets.
I used to be into them but since Mazda has made itself independent from Ford
its prices for spare parts are ridiculous.
As always pistons rule due to the X 10000000000000 more development invested in them
and the fact that its a failed architecture for F1 like rpm, top fuelers, drifting
and everyday driving.

Dont get me wrong i do love them as much as I love variety in anything but the fact is
they are expensive, inefficient and difficult to register. However for light aircraft
they rule over existing super expensive lycoming and other overpriced brands.
Also in single rotor turbo guise they are almost as affordable as a 2liter four cylinder.