Why hasn't the use of LDR rotors prevailed in race engines?
 

Ok so I've been reading Kenichi Yamamoto's technical book on the Rotary engine and I had a question for those with real-world experience.

He mentions to use of LDR (Leading Deep Recess) rotors which provide a deeper rotor recess on the leading side of the rotor for better combustion. From the data provided in the book, it looks like LDR rotors provide higher performance at the cost of higher emissions. However this shouldn't be much of a problem for most race cars since emissions aren't a limiting factor.

So what's the deal, everybody? I know some aftermarket companies have experimented with lightened and machined rotors, why hasn't anyone developed LDR racing rotors yet?

Not really any way to modify that part of the rotor without increasing the compression ratio for one... and for another, the casting isn't really thick enough to make that much in the way of changes there.

Note that 12A rotors aren't symmetric like the later ones are and actually are shaped like that.

Why are MFR race rotors for 12As MDR? I was at Pettit racing's shop and saw a set of 12A race rotors, and they were symmetrical, though the dish was very small for compression.