Ok, hopefully someone can answer this question and its not as long as rotary engine weight. But I will more specific than that post.

I'm reading over the new Summit catalog for sport compact(i get all the catalogs). And I'm looking over the electric water pumps. Well I see this:

Mazda Rotary Water Pump Adapter Block

This adapter block allows you to mount the Mazda rotary water pump directly to the engine. It includes two 3/4" NPT and one 1" NPT outlet. Fittings sold seperately.

$89.95

So are the water pumps on 12a's and 13b's so good that they are being put on Hondas?

 

No. It's for an electric water pump. Read the info again and visit Meziere's website.