3.73s to 3.31s

[Jrt]

Hey guys need some help,I have a 2015 gt performance pack with 3.73s it is a manual car that is boosted has around 700whp ..so 1st gear is useless my question is would 3.31s be my best bet and also di I need to have the car returned for the gears beings that it's a manual car?

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[kcobra]

I put some 3.31's in my BOSS with around the same power also. I love them. More usable gears. The only downside is you can actually bog in 6th when going up a small grade and not going fast enough. It takes a bit to get used to. But I would recommend it.

 

[Jrt]

Did you have to retune it? I never use 6th gear anyways

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[kcobra]

No. Just reprogrammed the differential calibration for the speedo correction.

 

[scotmach]

There are no changes made in the PCM on 2015+ cars since the information is stored in the BCM. You will need to address that should you swap to 3.31's.

 

[Jrt]

There are no changes made in the PCM on 2015+ cars since the information is stored in the BCM. You will need to address that should you swap to 3.31's.

Address what?

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[Jrt]

No. Just reprogrammed the differential calibration for the speedo correction.

Does anyone know if the pumpkins all interchange from EcoBoost to gt? So I can just swap the whole thing

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[ashleyroachclip]

Making two threads on the same topic I see .
Not getting enough attention ?

 

[Jrt]

Making two threads on the same topic I see .
Not getting enough attention ?

Lmao..not that I just really need to know if they interchange before I make a purchase tomorrow

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[Jrt]

Making two threads on the same topic I see .
Not getting enough attention ?

I'm about 100 percent positive that they will

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[ashleyroachclip]

Only because you had to quote me from them both .......

 

[pwt's17]

Seems I read that the 4 and 6 cylinder pumpkins are aluminum, while the GT pumpkin is iron or steel.

 

[Jrt]

Seems I read that the 4 and 6 cylinder pumpkins are aluminum, while the GT pumpkin is iron or steel.

I believe I've found out through several calls that there is a Aluminium and steel version for sure, they are all the exact same except those features and gearing.

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[pwt's17]

My research suggests the change to steel on the GT was for strength. Apparently the aluminum version was thought to be too weak for 435 horsepower. I would think putting the aluminum pumpkin behind 700 horsepower would not end well.

 

[Jrt]

My research suggests the change to steel on the GT was for strength. Apparently the aluminum version was thought to be too weak for 435 horsepower. I would think putting the aluminum pumpkin behind 700 horsepower would not end well.

I agree..I found a cast steel housing with 331s,thanks for the response

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[scotmach]

Address what?

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The BCM which I clearly stated above.

 

[Jrt]

The BCM which I clearly stated above.

Oh..so after finally talking to with my tuner he made it clear there will be no need for a retune on my year with a manual..

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[CobraBob]

You will need to correct the speedometer reading for the new ratio.

 

[Jrt]

I thought the same but my tuner is telling me after a few drive cycles it will correct itself

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[scotmach]

Then your tuner is a moron. The speedo gets its information from the BCM. The fact he doesn't know this would scare the shit out of me. Do a search.
Changing rear gear from 3.73 to 3.31 speedometer recalibration question