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Discussion Starter #1
N/a SBC 434" using a 4" arm looking to shift around 7800-8,000RPMs in a 3200Lbs first gen F-body. Trans is a 1.90 ratio comp style low drag Powerglide and a 12-bolt rear axle stock Calvert racing rear suspension. Convertor is a 8" 6200 stall to start that will get worked on as we go. Tire is the 3055s or possibly a 275/60-15 but something close to 28" tall.

I am thinking 4.56 or 4.88s but I would like to hear what others have used or found with similar setups on max N/A deals? I am told the convertor and gearing play a big part in getting the Powerglide to work. Thanks for any info.

Tedd J.
 

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800 @ 3200 will go close to 150mph on the quarter and low 9s and if you want to trap near your 8k 4.33s will get you closer than 4.56s on a 28in tire. Even 4.4s would work but I would not in any lower.
 

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I'm thinking you're pretty good with your thoughts (~4.67) But others think a higher ratio & I respectfully wonder why
 

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Its just math 148 mph 8000 rpm peak power

Tire HeightMPHRPMTrans RatioConv Slip%Rearend RatioEnter the Tire Height in inches,
The ¼ Mile MPH, the RPM,
the Transmission top gear ratio
Conv Slip% and
Click on Calculate...
Rearend Ratio = (RPM * Tire Height) / MPH * 336.136 * Trans Ratio * Conv Slip%)



http://www.tciauto.com/Products/TechInfo/Calculators.asp

Bottom of page I would use about 4-5% slip in converter if its good

The tire will not grow the converter will slip more than 5% should put you about 500 rpm past peak if its at 8000
 

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Discussion Starter #12
Thanks everyone for the info I'm glad I asked befor I spent the $$$$. Thanks Jeff for the TCI link there is some good info there.
 
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