Change differential 3.15 on 3.55.

[any_key]

On paper top speed will decrease. But in reality, top speed will increase.

How is that? )))))))

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[Emilbadal]

I destroyed my stock 3.15 gear and for the change I went with the FP 3.55 unit. In terms of 0-60 times I haven't seen any improvement at all, however the car feels that it pulls harder than before and it feels that it gets into powerband a bit faster but statistically it may improve ~0.1 sec Maybe. I wouldn't go over 3.55 though, because of the HWY speeds cruising RPMs.

 

[80FoxCoupe]

How is that? )))))))

Aerodynamic drag limits top speed in lower horsepower applications, not an rpm limit. With a 3.55 you will be at a higher engine rpm at that point. Higher rpm equals more power. More power will push the top speed up a touch.

 

[GilmourD]

On paper top speed will decrease. But in reality, top speed will increase.

Well, mathematically, redlining the engine in 6th gear will always be the same RPM but result in less rotations of the rear wheels with higher ratios. It all depends on how high you could spin up the engine before it decides to become a weapon, but the math is the math.

 

[80FoxCoupe]

Well, mathematically, redlining the engine in 6th gear will always be the same RPM but result in less rotations of the rear wheels with higher ratios. It all depends on how high you could spin up the engine before it decides to become a weapon, but the math is the math.

You won't be able to overcome aerodynamic drag in 6th Gear. Reality is reality.

 

[Jstang23]

The amount of aerodynamic drag you would experience at the top of 6 or whatever gear you are comparing would be too much to notice any difference from the 3.15 to 3.55 for top speed. You would have to change it to 4.10 or 4.60 to notice that change for aerodynamic resistance. Even then you are talking 1-2 mph. But at the point to where the difference in speed would register on the Speedo you would have lost so many rpm’s per gear you’d actually be slower.

We‘ve already discussed this at length in another thread.

 

[LOL WUT]

Don’t fear the gear. Toss in some 4.90s.

 

[80FoxCoupe]

The amount of aerodynamic drag you would experience at the top of 6 or whatever gear you are comparing would be too much to notice any difference from the 3.15 to 3.55 for top speed. You would have to change it to 4.10 or 4.60 to notice that change for aerodynamic resistance. Even then you are talking 1-2 mph. But at the point to where the difference in speed would register on the Speedo you would have lost so many rpm’s per gear you’d actually be slower.

We‘ve already discussed this at length in another thread.

The gain may be minimal, but a gain nevertheless.

 

[80FoxCoupe]

Don’t fear the gear. Toss in some 4.90s.

Now that's a plan. The s550 world is far to conservative to entertain that tho.

 

[Jstang23]

The gain may be minimal, but a gain nevertheless.

A gain of .3857 mph

 

[K4fxd]

The gain may be minimal, but a gain nevertheless.

Just add a smaller pulley..... or bigger if you put it on the crank.

 

[ShadesOfBloo]

Acceleration will increase, top speed will decrease.

How is that? )))))))

Top speed for each gear will decrease, because it will reach the RPM limit at a lower speed.
No matter what you do with the gears, there is still software that limits your speed to 250km/hr. That would limit your top speed in 7th gear.

There is a comparison table 3.15, 3.55, 3.73 - what rpm will be at speeds of 60 mph, 100 mph, 120 mph, etc.?

That depends on the size of your tires.

 

[K4fxd]

Top speed for each gear will decrease, because it will reach redline at a lower speed.

in a vacuum. Gears multiply torque, power.

There is still a line of software that limits your speed to 250 km/hr

easily removed

That depends on the size of your tires.

very true

 

[Joe B.]

I'm wondering how many revolutions there will be in 10th gear on the highway at 60 or 100 miles (how comfortable it will be to drive on the highway in a pair of 3.55).

And the goal is I want to improve the dynamics of the car in the city.

Probably not much change in "dynamics" in the city.

 

[K4fxd]

Probably not much change in "dynamics" in the city.

Which is why I say I should have gone with 3.73. With the A-10 final OD gear 4.09 would probably be the best.

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