Mopar Performance Crankshaft

I have a Mopar Performance 3.510" stroke forged crankshaft that I picked up a long time ago. I seem to remember that these were developed for a spec racing class either within NASCAR or possibly sprint cars. Does this sound familiar to any of you? Do you possibly remember the "formula" (pistons, rods, etc.) they followed? I've messed with simple calculations on 318s, 340s & 360s but haven't hit on anything yet that seems obvious.

does it have 340 or 360 main bearing size?

273-340. My "look" at the 360 was just to see where the numbers would fall even though this crankshaft wouldn't have a 360 application. Dropping this into a stock bore 318 = 342CI and a 340 = 360CI (albeit with a shorter stroke than a production 360). Possibly this was the intent.

Don't most of the circle track classes have a 358" limit?
I go a block from a local guy and he put 8 sleeves in it
because the class allowed Mopars to run at 360".
This could explain the stroke.

You may very well be right. With a 3.51" stroke, a +.030" over 360 bore would yield a 358 ci displacement with a gain in getting off of the corners...

But then I dug out a set of pistons that I got with the crankshaft... They were listed as 340/360 pistons with a bore of 4.060" (so +.060" over 360 or, +.020" over 340). They were also listed as designed for a stock rod length 8.123" and a stroke of 3.510". This messes up the 358 spec class idea since this bore and stroke would yield 363CI. Possibly there are smaller bore pistons made for the same stroke that would make the 358CI formula (such as a +.030" over 360 piston).

MP had a bunch of different strokes available on these 1053 Steel cranks. I think the idea was to go to a shorter stroke when the block would be bored/honed to the next size. I have one of the 3.51" stroke cranks, as well as a 3.55" and a 3.65" stroke. When they put them on sale, they sold some pistons too, but they didn't match up with the crank strokes well. One set was listed for a 3.54" stroke, but was really for the 3.45" stroke (old 355 combo).

That's pretty interesting. I had not heard of the other crankshafts that were all pretty close to the 3.58. Given they were close (but marginally different) the re-bore displacement idea makes sense but do you think that was tied to a racing class rather than road cars?

using 8.123" rod length math will really mess you up.

Whoops. No kidding. Sorry about that!