We tend to think about rotaries when we think about Mazda engines, but it would really be stretching the definition of "workhorse" to include Mazda's Wankel in this series (perhaps we will do a Supercool Screamin' Engine of the Day series at some point, just so we can rant on about RX-3s, Cosmos, etc.). However, Mazda has made some strong and reliable piston engines as well (just to show they're not philosophically opposed to reciprocating mass), and today we honor one such engine: the Mazda B series. They started making Bs in 1987, they're still making them today, and they've powered a staggeringly long list of makes and models, from Miatas to Escorts to Sephias. [Wikipedia]
I loves me my B series. It has served me well in an Escort GT and two Miatas. My current B has survived countless lashings of the rev limiter and a severe mechanical overrev (4th —> 3rd not 5th) and is still snorthing along happily awaiting more hoonage.