Rod length question

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Mike Van Veghten
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Joined: 02 Sep 2005, 12:06
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Rod length question

Post by Mike Van Veghten » 24 Jul 2020, 17:10

Just curious -

Has anyone built a "short rod" Stude engine ?

Like using a stock Chevy (5.7") rod. Just thinking, how it would work with the low flow heads on the Stude engine. It might also be better suited to the lower rpm of the Stude engine. Most Stude engines don't run to 8000/9000rpm+, while many small Chevys do in most types of racing (I know, many have 6"+ lengths).
Or...even more-so with a small/medium inch V-8 Ford rod length..!

MIke

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PackardV8
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Joined: 24 Nov 2005, 09:51

Re: Rod length question

Post by PackardV8 » 24 Jul 2020, 19:39

Hi, Mike,

Yes, the theory is correct, but the practice is bad. To use a shorter rod in a Studebaker V8 would require a very tall (2.5" compression height), thus very heavy piston. The losses would probably exceed the gains.

FWIW, a Pro Stock builder, when asked how long should rods be, "Long enough to connect the crank and the piston. Beyond that, don't I worry about it"

jack vines

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Mike Van Veghten
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Joined: 02 Sep 2005, 12:06
Location: West Coast

Re: Rod length question

Post by Mike Van Veghten » 25 Jul 2020, 01:49

With todays pistone designs, I doubt that there would be a huge difference in weight. I'd bet that a longer compression height piston could be machined that weighs close to a stock piston weight.
Last I heard, most motorcycle engines run a shorter than "ideal" length, and they make plenty of power for their size.

Yes, I've heard all of the anecdotes, just wondering if it had been done.
As you know, following the leader...ALWAYS puts you at least...second.
Just thinking out loud. My rods and pistons have already been bought.

Mike

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63larkr1
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Joined: 17 Dec 2003, 16:49
Location: Nashville, In

Re: Rod length question

Post by 63larkr1 » 29 Jul 2020, 12:54

This is the rod I used in my engine. You can do much better on the price.

6.560 CRS6560H3D2000 650g H-Beam 1.8890 0.927 1300 HP 665.33

These will work with a spacer they sell, I have no experience with this set.

6.560 CRS6560O3D2000 650g H-Beam 2.1000 0.927 1300 HP 665.33

Richard
Studebaker Drag Racing You can't beat it.
The 11th annual all Studebaker Nationals Drag Race is Saturday May 25th, 2018 at 9:00 am at Brown County Dragway in Bean Blossom, Indiana. For more information contact Richard Poe

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