Crank Journal Size: Mopar Versus Chevy

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justinp61 said:
You’ve lost me. Not that’s hard to do. LOL
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You have a stock Mopar crank. You want to run Chevy rods and bearings. The machine work to get it done costs to ME outweigh any advantages. Because now you have the cost of machining the crank, PLUS buying the Chevy stuff. I get it about the decreased weight, blah blah blah. But for all but the most serious race engines, IMO it's not necessary. Maybe one running above 7K, I could see it. I'd like to see some dyno pulls between an all Chrysler engine and a "Chevyed up" one to see any differences. My guess is it won't be enough difference for all the trouble. ....and yeah, I know, it's not necessarily about the power difference, but the weight reduction. I get that.
 
RustyRatRod said:
You have a stock Mopar crank. You want to run Chevy rods and bearings. The machine work to get it done costs to ME outweigh any advantages. Because now you have the cost of machining the crank, PLUS buying the Chevy stuff. I get it about the decreased weight, blah blah blah. But for all but the most serious race engines, IMO it's not necessary. Maybe one running above 7K, I could see it. I'd like to see some dyno pulls between an all Chrysler engine and a "Chevyed up" one to see any differences. My guess is it won't be enough difference for all the trouble. ....and yeah, I know, it's not necessarily about the power difference, but the weight reduction. I get that.
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I agree on the stock crank, I wouldn’t cut it. didn't the OP say he was buying a 4” crank though?
 
justinp61 said:
I agree on the stock crank, I wouldn’t cut it. didn't the OP say he was buying a 4” crank though?
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I think so, yeah. I've agreed with that. If you're gonna go the Chevy route that's probably the best way. Then there's little to no cost difference.
 
Isn't some of the reasoning you can do smaller journals is better technology than 50 years ago?

The oil we can use is better. And lighter and stronger: piston, rod, rings, pins, bolts. Fracture split connecting rods that are more precise, stronger, and cheaper to make.

I would think a Small Block Mopar with 4" stroke would even be fine with 1.88" Honda journals at under 550 HP ??
 
autoxcuda said:
Isn't some of the reasoning you can do smaller journals is better technology than 50 years ago?

The oil we can use is better. And lighter and stronger: piston, rod, rings, pins, bolts. Fracture split connecting rods that are more precise, stronger, and cheaper to make.

I would think a Small Block Mopar with 4" stroke would even be fine with 1.88" Honda journals at under 550 HP ??
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When I hurt my old 408 with K1 Chevy sized rods and crank a Moparts member I think from Australia contacted me and asked if I would sell the assembly to him. I sent him a ton of pictures of the damage and he didn’t care because they cut their stuff to Honda size. I just had to send the stuff to the east coast where he had a shipping container. God bless those guys and the desire they have for racing. Talking about expensive.
 
Don't nascar engines use 1.88" rod journals?
 
pittsburghracer said:
Pretty sure Hugh’s offers it with a lot of their stroker kits. Or was it Mancinni’s.
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Hughes, I think.
Rat Bastid said:
Yes. pro Stock and Comp too.

Probably most guys should be running 2 inch rod throws. But that limits off the shelf rods you can buy.
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My 4" engine used 2.100" X 6.125" rods and the 4.125" engine uses 2.00" X 6.200" rods. Both use a .927" pin.
 
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