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Mopar Performance Crankshaft #2894608 03/01/21 10:49 PM 03/01/21 10:49 PM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	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.

Re: Mopar Performance Crankshaft [Re: earlymopar] #2894624 03/01/21 11:29 PM 03/01/21 11:29 PM
Joined: Jan 2003 Posts: 9,826 las vegas 70AARcuda master
70AARcuda master Joined: Jan 2003 Posts: 9,826 las vegas	does it have 340 or 360 main bearing size? Tony 70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)

Re: Mopar Performance Crankshaft [Re: 70AARcuda] #2894675 03/02/21 08:45 AM 03/02/21 08:45 AM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	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.

Re: Mopar Performance Crankshaft [Re: earlymopar] #2894720 03/02/21 10:39 AM 03/02/21 10:39 AM
Joined: Jan 2007 Posts: 685 pennsylvania poboyengineering mopar
poboyengineering mopar Joined: Jan 2007 Posts: 685 pennsylvania	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. It may be ugly, but it sure is slow. Girls comb their hair in rear view mirrors and the boys try to look so hard....

Re: Mopar Performance Crankshaft [Re: poboyengineering] #2894805 03/02/21 02:00 PM 03/02/21 02:00 PM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	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...

Re: Mopar Performance Crankshaft [Re: earlymopar] #2895028 03/02/21 10:26 PM 03/02/21 10:26 PM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	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).

Re: Mopar Performance Crankshaft [Re: earlymopar] #2895077 03/03/21 01:40 AM 03/03/21 01:40 AM
Joined: Jan 2003 Posts: 3,504 DFW M mr_340 master
mr_340 master M Joined: Jan 2003 Posts: 3,504 DFW	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). Floyd Lippencott IV

Re: Mopar Performance Crankshaft [Re: mr_340] #2895127 03/03/21 09:30 AM 03/03/21 09:30 AM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	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?

Re: Mopar Performance Crankshaft [Re: earlymopar] #2895135 03/03/21 09:53 AM 03/03/21 09:53 AM
Joined: Jun 2008 Posts: 3,916 usa L lewtot184 master
lewtot184 master L Joined: Jun 2008 Posts: 3,916 usa	Originally Posted by earlymopar 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). using 8.123" rod length math will really mess you up.

Re: Mopar Performance Crankshaft [Re: lewtot184] #2895348 03/03/21 07:18 PM 03/03/21 07:18 PM
Joined: Jan 2003 Posts: 1,335 Oregon E earlymopar OP pro stock
earlymopar OP pro stock E Joined: Jan 2003 Posts: 1,335 Oregon	Whoops. No kidding. Sorry about that!

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