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#1 |
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What is the ideal gear for a 2600 lb tube chassis car with a 582 BBC and glide? Been running 4.10 with a 33" tall rear tire and it seems as it is hard to recover off stop and it wants more gear, say 4.56?
Thoughts? |
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#2 |
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Finish line RPM kinda puts you in the ballpark
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Phil Molski PMR Performance S/C 1623 |
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#3 |
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Would the 4.56 help coming off the stop to recover?
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#4 |
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I agree that I'd base the rear gear choice on finish line RPM. As for recovery coming off the stop, you can try a higher cruise RPM, coming off the stop in low gear, going on the stop later to get the car moving, etc.
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S/ST 51 S/C 53 |
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#5 |
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While it is true that finish line RPM plays a part, I was convinced a few years back by Eddie Jr, at Select Performance, to go to a 4.56 gear.. not only to enhance his converter set-up, but that I would be surprised by the charge coming off the stop.. I now have 2% to 3% slip in the converter at the top end, and that charge coming off the stop is awesome, and I go out the back door at approximately 7600 RPM with my 565.. I am only 2150 pounds also..
While I was a nay-sayer, until I switched from the 4.30, I doubt I'll go back.. while it slightly increased the RPM, I didn't seem to affect the MPH at all... |
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#6 | |
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Was there a measurable gain anywhere? Could you stay on the stop longer?
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S/ST 51 S/C 53 |
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#7 |
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Although I didn't mention MPH, I'm up between one and two.. also, I usually do stuff to try and take time out of the box.. not put more time in.. and I really don't like carrying 3.00 in the box either...
Last edited by Charlie Yannetti; 10-03-2020 at 04:42 PM. Reason: add to comment |
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#8 |
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rob7181,
Going from the 4.10 your running to say a 4.33 would only be a 5% increase, but going to a 4.56 is going to be a 9% overall increase in performance. Plus you should pick up around 3mph. |
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#9 |
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Like Charlie ,I run Select converters . I went to 4.56 gears from 4.29 in my Vette which weighs in at 2400# .
I picked up 2 mph with an increase of 250 trap rpm . converter efficiency went from 10% slip to 5-6%. AND very importantly , the converter temperature dropped way down when coming off the stop. Since Charlie's car is a '27 Roadster, one of the hardest cars to get MPH out of I'm not surprised by the lack of improvement in speed. I would defiantly recommend 4.56 gears in your car. Racers get too hung up on trap rpm's , if your engine is still pulling at the stripe ,let it eat !
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#10 |
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^^^^^^this
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