Thank You, Andrew. First yourself, then Tony Lockerbie recommended the steamy romance between HP5 & Pyro. At first I thought it was the only think that compared well w/ D76. Now, I find I don't want to run out of Pyro. What it does to metal is wonderful.
Yes, I'll toss in that for those in, or traveling in, the Northeast US, In Hammondsport, NY, in the Finger Lakes region (a worthy target for a lens in its own right), there is the Glenn Curtiss Museum. It seems in the middle of nowhere and from the highway, not very large, but ooo-weee! Radials, X-24 engines out of (B29s? ooops, no apparently not ...), which are works of art. And all sorts of stuff, not to mention (a reproduction of) the motorcycle with an air-cooled V8 (designed for aircraft use) that Curtiss himself drove to nearly 140mph -- circa 1907!
Well that is my term -- I forget its official name, but it was essentially two V12s stuck together with a gearbox linking the two crankshafts and the propeller drive -- one heck of a piece of machinery. I have pictures "somewhere" -- can't remember when I was there, so they may be electrocuted bits! Ah, maybe *not* for a B29, that appears to have been a twin radial -- total 18 cylinders!
A bit of Googling shows Allison made a "true" X24 in the mid-1920s; but the one stuck in what's left of my mind was a sort of fusion of two V12s -- could even be it was experimental, I suppose. "One of these days I'll find the pictures I took."