Quote:
Originally Posted by olddog
I saw on TV or read where the NASCAR teams run two different rod lengths in the same engine, based on the track. I do not recall which did what, but they claimed one rod length gives them an advantage accellerating out of the corners on the short tracks. The other is better for the long straight aways. If true, they have to be able to measure a difference or they wouldn't bother.
I did do some reading in my engine spec books, in bed the other night. I calculated what wrist pin height would be needed for this combination. No factory piston will fit the bill. I calculated the pin height for several strokers and none matched up. The 331 came the closest. I cannot recall the numbers, but I think it was close enough to possibly work with some machining. I wouldn't trust any of this as I did the math in my head and then slept on it.
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Not only running different rod lengths for different tracks, they also use different bore/strokes combinations for different tracks as well, all staying within the 358 cu.in. limit........
Short tracks,bigger bore,shorter stroke for quick accelaration off the corners,were the rpm range is greater: long tracks, smaller bore, longer stroke were the rpm range is smaller......
Before the compression rule (I think it is 12 to 1 now), Yates Racing was running engines at Talladega/Daytona in the 17 to 1 compression ratio!!!!!!!!!!!!!!!!
David