Rear Gear - did some research

[Ranebowcyxx]

I have run 3.73 on my last few cars. Blowers, Nitrous, NA. I have never run a car with a small motor and turbo. Any real world users out there that have run 3.73s? How about 3.55s?

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[mcky2011]

My 2 cents.
Rear gearing is part of the equation and there is no one size fits all.
I have a 68 C10 with a 2010 6.2 L99, 6L80E with 3.73.
It is stuffed with BTR goodies and after an hour or so on the dyno the very well known/respected tuner said I should put something like 3.08s in the rear to maximize the power and the 6L80.
It has 414 HP and 406 TQ at the tire.

 

[80FoxCoupe]

My 2 cents.
Rear gearing is part of the equation and there is no one size fits all.
I have a 68 C10 with a 2010 6.2 L99, 6L80E with 3.73.
It is stuffed with BTR goodies and after an hour or so on the dyno the very well known/respected tuner said I should put something like 3.08s in the rear to maximize the power and the 6L80.
It has 414 HP and 406 TQ at the tire.

What in the world does this have to do with the OPs question???

 

[Ranebowcyxx]

The reason I asked was with my limited, (almost none) knowledge of how turbos .ake power. My understanding is that you want the turbo to work and if the the gearing is too short you won't get the most efficiency and power of the turbo.
I still have to believe that shorter gearing will improve acceleration at the cost of top end.

 

[MD18EcoStang]

I have run 3.73 on my last few cars. Blowers, Nitrous, NA. I have never run a car with a small motor and turbo. Any real world users out there that have run 3.73s? How about 3.55s?

I have no experience with changing the gearing, but I do know my 18 MT performance package model came with 3.55 gears, so at least that's not too uncommon. I don't track my car, but I like how it feels on the street. Nothing to compare it to, though.

 

[Coyote Chase]

Which transmission and what modifications do you have?
My track only (1/4 mile drag strip) 2018 Ecoboost Mustang is equipped with the 10R80 transmission and 3.15 gears.
I've had a lot of (pre-3000 rpm) tuning issues, so my data isn't what I would like it to be.
But when I launch at 1750 rpm, in first gear, I need to shift into 2nd, pretty quick, so I'll probably switch to a 3.31 gear.
However, with my stock transmission and stock torque converter, I am able to launch at 2500 rpm, in 2nd gear, therefore, I'll probably switch to 3.73 gears.

PS: Most guys I have spoken to, with the 6 speed standard or 6 speed automatic, prefer 3.55 gears.

 

[Ranebowcyxx]

Good replies and insight.
For now I have a Cobb CAI, adding CV charge pipes this weekend and for now a base tune from PD. I want to get the charge pipes on and data log.
Future is upgraded IC and chatted down pipe. I'm not going into the motor like I did on my last few cars.

 

[80FoxCoupe]

The reason I asked was with my limited, (almost none) knowledge of how turbos .ake power. My understanding is that you want the turbo to work and if the the gearing is too short you won't get the most efficiency and power of the turbo.
I still have to believe that shorter gearing will improve acceleration at the cost of top end.

Let's start with intended use of the vehicle? What transmission do you have?

 

[TeeLew]

The drag guys with built engines generally run a 3.31. With lower gears (higher numerically) wheelspin is harder to control and you have too many shifts. This seems to be a better choice for a lower RPM engine with plenty of low end torque.

I run a 6MT mostly for autocross. I'm moving to a 3.15 specifically to reduce shifts. I'm better off lugging the engine a bit in really slow corners and not shifting than a shorter rear gear, a little better acceleration and having to shift between 2nd & 3rd.

In normal driving, the 3.55 is too short. I shift to 5th way too often driving in town. There's just no need for this engine to run short gears. If you have an N/A engine that loves RPM, then 3.73's are a nice gain on the launch. We don't have that.

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