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3.73s or 3.90s?

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3.73s or 3.90s?

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Old

Dec 17, 2023 | 04:57 PM

#1

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3.73s or 3.90s?

Is there a huge difference between 3.73s and 3.90s? I've got a 525 HP LS1. Are 3.90s much shorter than 3.73s? Will I notice it on the street? Currently I have 3.42s. running 18" C5 Vette wheels size 275 35 18 front and back. If possible, I want to be able to utilize 6th gear on the highway and cruise at 90 below 2400rpms. I'm thinking that's 3.73s. Currently, 3.42s run 2000 rpms at 90.

Last edited by Mezzy; Dec 29, 2023 at 01:37 PM.

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Dec 17, 2023 | 05:15 PM

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General rule is 4L60E autos like the 3.73s and manuals like the 4.10s. If you have the .5 overdrive the 3.90s will work on the highway and get off the line quickly.

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Dec 17, 2023 | 06:04 PM

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Quick dirty rule of thumb is 150rpm for each jump in gear size. So 3.90’s would net 78ish mph at 2k rpm. 2300rpms at 90mph. (25.7” tire, .50 final)

https://spicerparts.com/calculators/...rpm-calculator

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Dec 17, 2023 | 06:30 PM

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i would go 3.90 or 4.10s

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