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 Post subject: Gear Ratio for Altered
 Post Posted: Tue Sep 11, 2012 10:37 pm 
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Joined: Sat Jul 14, 2012 12:04 am
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Have an Altered Roadster, 1600 lbs, mild 388 sbc with estimated 450 hp, powerglide with 5000 rpm stall converter, 32 x 14 MT's. Present gearing is 5.13, runs 6.65 @ 100mph in the eighth and 10.70 @ 119 in the quarter at 3500 feet altitude ,corrected to 6000 density altitude. Am thinking of going to 4.86 or 4.57 rear gears. What ratio are some of you guys running who have similar car. Need to get the gear set ordered soon. Thanks


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 Post Posted: Tue Sep 11, 2012 10:55 pm 
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Question is, what makes you think that you need to change it?

I think Rick360 has a roadster that runs close to yours so maybe he can give you info on what his is doing.

If you're looking to move the top end RPM down then you can use one of these formulas to get an idea of what that change will do RPM wise.

viewtopic.php?f=4&t=7859

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Necessity is the plea for every infringement of human freedom. It is the argument of tyrants; it is the creed of slaves.

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 Post Posted: Wed Sep 12, 2012 12:25 am 
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Guys I'm well versed on calculations and such. So as not to launch off into a long story of all my testing and such, all I'm looking for is the gear others are running with a combination similar to mine.
Thanks


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 Post Posted: Wed Sep 12, 2012 6:41 am 
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What rear?? 9" Do you run mostly 1/8 or 1/4? What is your rpm at the stripe?

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running E85
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 Post Posted: Wed Sep 12, 2012 8:03 am 
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I am running very similar times to you in my roadster and I have a 4.56 gear. I never noticed the finish line rpm, but I shift at 6200. It would surely be faster with more gear. It weighs 1930# and 16x32 tires. The 4.56 was not selected for this combo but what was there from another combo.

Why are you wanting to change? consistency or to improve et?

Rick


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