FE Power Forums
FE Power Forums => Non-FE Discussion Forum => Topic started by: gregaba on July 01, 2021, 03:17:50 PM
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May be you guys all ready know this but it is a new one for me.
Reading today that the MK1V 427 engine running in nascar and at the drags in the 60's and 70's were running a full rollerized crank.
Both rods and mains were rollered and they used a special hardened crank.
I was wondering why they ran so good while the 427 in my 67 vette seemed so lazy.
Greg
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I doubt there was much to gained with roller bearings. Think about it, Your rods and crank ride on an oil wedge with virtually no metal to metal contact other than at start up. I would think you would actually lose hp. with rollers. Roller cams are another story.
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I'd be curious about where you read that because I seriously doubt that's true.
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The Old Motor-Page 80.
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O.K. but......
I also seriously doubt this multi-part crank/bearing design ever ran in any NASCAR Chevy at any track...ever.
Seems like a engineering design or maybe a wet dream. Having read copiously about engine blow-ups and other failures on the so called Mystery Motor used in real NASCAR events, never was this radical idea mentioned.
Keep in mind we old timers (oops, I did it again!) well remember all the exotic engines that were depicted on the covers of Hot Rod magazine. Just a few from memory: 4-cam 455 Olds engine, SOHC SBC with a belt drive, DOHC Chrysler 426 Hemi.
Yeah, these engines were one-off designs that went nowhere. And I know that JJ's Smokey Yunick built 427 Chevy engines in NASCAR had plain old babbitt-type bearings instead. See: https://hotrodenginetech.com/chevrolet-427-mystery-motor/
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...and then there was Honda's 4-cylinder V8 equivalent with oval pistons and two rods per piston running at 15,000++ rpms....
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I just read it on the internet. Therefore it’s true.
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...and then there was Honda's 4-cylinder V8 equivalent with oval pistons and two rods per piston running at 15,000++ rpms....
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And I believe eight valves per cyl.!
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In order to run roller bearings you need a pressed together crank, which I would think would be a problem in an endurance engine... Old Britt and Italian bikes ran roller main and rod bearing.. Somewhere I remember a test and there was no power difference between shell and roller bearings
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Royce, one of our stickshift racers runs a low 10 second VW Beetle, and he said that years ago, roller bearing cranks were semi popular with the faster VW racers back then, but not anymore, as there was no performance benefit, the cost was considerably higher, and maintainance was a real hassle, . Not to mention you would think that having to separate and press the crankshaft back together, that the press fit would diminish after repeated disassemblies.