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Long rods........

June 19 2017 at 4:15 AM
Bob   (Login machoneman)

Response to Just a bench build

Not to rain on any parade, but I copied over R-M's thoughts on long rod engines as an FYI:

"I'm sure Darin Morgan will comment on this.They have a lot of experience with testing different rod lengths. Here's a quote from Reher-Morrison's site from David Reher and his thoughts on the subject".

" We also wanted to point out some of the common myths and misconceptions about high-performance motors. For example, I've seen dozens of magazine articles on supposedly "magic" connecting rod ratios. If you believe these stories, you would think that the ratio of the connecting rod length to the crankshaft stroke is vitally important to performance. Well, in my view, the most important thing about a connecting rod is whether or not the bolts are torqued!

If I had to make a list of the ten most important specifications in a racing engine, connecting rod length would rank about fiftieth. Back in the days when Buddy Morrison and I built dozens of small-block Modified motors, we earnestly believed that an engine needed a 1.9:1 rod/stroke ratio. Today every Pro Stock team uses blocks with super-short deck heights, and we couldn't care less about the rod ratio. A short deck height improves the alignment between the intake manifold runners and the cylinder head intake ports, and helps to stabilize the valvetrain. These are much more important considerations than the rod-to-stroke ratio. There's no magic - a rod's function is to connect the piston to the crankshaft. Period."

This is located in the tech article "by the book" if anyone else wants to read the whole thing. Hope Darin does comment on this, he has some deeper thoughts on this with a GM backed test to back them up.

This message has been edited by machoneman on Jun 19, 2017 4:15 AM

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