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th350 and 4.30's

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Old Aug 6, 2008 | 06:20 PM
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Default th350 and 4.30's

I've used all these different sites that tell you how to figure max mph and it says I should run a max mph of 124mph @ 6400rpm with a th350/4000stall/4.30's/28" tires. But, I am maxing out well before the finish line and it's no where even close to 124mph. What gives? Can these calculators be that far off?
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Old Aug 7, 2008 | 06:19 AM
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Its due to converter slip. Your running out of RPM
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Old Aug 7, 2008 | 03:06 PM
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So if I step down to around 3600 will that make it any better? Sorry if these are dumb questions but I am a 6 speed guy.
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Old Aug 7, 2008 | 03:08 PM
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I'd drop gear not converter dude. I dropped from my T56 gear(4.22) to a 3.90 when i went to a TH350. It seems to be working very well.
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Old Aug 7, 2008 | 05:00 PM
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I might throw in a set of 3.73's. We have a complete setup ready to go. Also have some 4.11's I can put back in there
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Old Aug 8, 2008 | 08:36 PM
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From a 4.11 to 4.30 is like only 150rpm. 4.11 to 4.56 is like 325rpm. I just went threw all this. And im running a glide with a 1.76 gear, 9in, 3.50 gear, and 28w tires and im crossing at 6100 off the nos. With the 4.30 im crossing at 6800 off the nos. In the old car i had a th400, 4000, 4.56, and 26" tire. I was crossing at around 6850. With my 315's on, it would not finish the 1/4. Hitting rev. Thos were 25". Anyway, hope this help ya.
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Old Aug 9, 2008 | 12:04 AM
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Your setup would be good for 1/8th mile.

With a th350, 3.70 gears, 27" tire, 6300 rev limiter my car will tag the rev limiter right before the line in the 1/4. Can fix that two ways. Run a 28" tire or bump the rev limiter up a little.

Have seen several people do this combo for the 1/4. th350, 4.10 gears, 28" tire, 6700 rev limiter.

Thats why you'll see cars at the track with 4.56/5.xx gears running 30+" tires.
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Old Aug 9, 2008 | 01:08 AM
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Thanks for the input guys. I took it back to the track tonight to run the 1/8th mile jackpot race and it run a best pass of 7.41@92mph with a 1.58 60ft foot braking it from 3000rpm.
I did make a couple of passes all out and it would make it almost exactly to the 1000ft at 65-6600rpm where I was getting out of it and coasting to a 11.71@92mph. I'm thinking 3.89's would be about right.
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