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Why higher gearing?

LethalPerformance

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It's just calibrating the speedometer.

It's not just to get the speedo right. If the PCM has a different gear ratio than the body control module the torque tables will be all messed up as they both communicate with each other. Most likely the car won't run as it should and I highly doubt you'll be able to make a solid pass at a track.

Jared
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Guard5.0

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I'm a manual pp car, aiming for 750-800rwhp and will be a combo of drag strip and city. This car isn't my daily
I'm only at 550 rwhp with the 3.73's and the car has to be nursed through 1st and 2nd under boost. 3rd can be iffy. At the levels you're talking you'll spend a lot of time feathering the throttle and being amazed at how quickly you need to shift. I will be making the change soon to the 31's or 55's, just haven't decided which yet.
 

mustang_guy

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I'm only at 550 rwhp with the 3.73's and the car has to be nursed through 1st and 2nd under boost. 3rd can be iffy. At the levels you're talking you'll spend a lot of time feathering the throttle and being amazed at how quickly you need to shift. I will be making the change soon to the 31's or 55's, just haven't decided which yet.
Thats because you're using a pd blower. They have traction issues.
 

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WhiplashGo

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So if you get a Whipple (650-700 rwhp range) & have an automatic, is 3:31 the best gear ratio for a car that is used for 1/4 mile passes & street driven?
 

LethalPerformance

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jasonstang

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It's not just to get the speedo right. If the PCM has a different gear ratio than the body control module the torque tables will be all messed up as they both communicate with each other. Most likely the car won't run as it should and I highly doubt you'll be able to make a solid pass at a track.

Jared
That is very interesting. So stock control also adjust torque accordingly?
 

Higgs Boson

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HP tuners can change the gear ratio in the tune. It won't be able to flash the body control module though.

Hope that helps.

Jared
HPTuners disabled the speed ratio calculation. Or, you can adjust the ratio calculation if you want.

Point being, you don't need to flash the BCM to correctly tune for gears and tire size changes in HPT.




http://www.hptuners.com/forum/showt...rans-Tuning-Tip-N-V-Base&highlight=gear+ratio

http://www.hptuners.com/forum/showt...tang-gt-auto-gear-change&highlight=gear+ratio
 

Guard5.0

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Not if you like winning races. A properly set up turbo or centri will wreck you by the time you find traction. :cheers: dont misunderstand boost is fun regardless but i play to win.
So a PD car can't be "properly set up" to achieve traction because it hits too hard? If there are 3 cars, a TT, centri, and a PD, all making exact hp and tq numbers, and all are properly prepped for maximum traction given the existing conditions the PD couldn't win a drag race?
 

mustang_guy

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So a PD car can't be "properly set up" to achieve traction because it hits too hard? If there are 3 cars, a TT, centri, and a PD, all making exact hp and tq numbers, and all are properly prepped for maximum traction given the existing conditions the PD couldn't win a drag race?
Peak numbers mean nothing. From what ive seen it doesnt hang with centri and tt. Btw good luck getting a pd blower to hook well enough on the street. Centri and tt or singles rule at the strip. Its just how it is. Dont misunderstand i like pd blowers but for a drag racer they dont seem to do as well. But what it takes from what ive seen to get pd blowers to hook its not a street going car. Its usually a full on dragster. The fastest street and strip and majority of strip cars run centri and turbo
 

beefcake

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don't forget we have the new wavetrack diffs available if your in there doing gears
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