Gear Ratio

[LODOSS]

I've searched with no luck.

Does anyone have the gearing info on the auto and manual trans in the B8 S4?

[borutp]

"The maximum possible transmission-ratio spread of 8.0:1 allows a sporty, short transmission ratio for the first gear as well as an rpm-sinking, long ratio for the last gear. The seven-speed S tronic is designed for up to 9,000 rpm and can transmit torque of up to 550 Nm."

http://germancarscene.com/2008/03/19/the-new-audi-s-tronic-7-speed-gearbox/

[L0U]

I've searched with no luck.

Does anyone have the gearing info on the auto and manual trans in the B8 S4?

The shootout test done recently between the ford,335i,s4 has the ratios for the s-tronic, and the final drive.

From what I recall, the 7th gear is very over drive. Hows 1870rpm at 100km/hr grab yah.

The other factor is that the 0 to 60 times require only 1 shift. This helped achieve the 4.9 seconds.

http://forums.fourtitude.com/zerothread?cmd=print&id=4506123

Lou

[LODOSS]

Exactly what I was looking for.

So the BMW 335I 6th gear is still longer and very slightly more fuel efficient than the S4s 7th.

Actual ratio

6th = 2.3874 bmw 335i

7th = 2.4056 Audi S4

The S4's superior accelleration must come from its gearing.

The BMW 335I we know is underrated and clearly it has a better power/weight ratio.. there is no reason why it would fall that much behind unless there is something else in the works.

[L0U]

First gear in the audi is taller than the BMW's yet it outpaces the Bimmer to 60KM/hr. This is likely the AWD. remember that this was the dsg though, and it is supposed to be slower off the line than the manual. :)

Other factor...the Audi is looking to be closer to 360hp and not 333hp at the crank. Expect the dyno runs from others to verify the "conservative" numbers from the S4. The 2 litre rated at 200 was way off as well.

[savagemash]

I don't know the ratio, but I'm shifting into 3rd at 10mph, using 5th as the speedo passes 20mph, and into 6th by 30mph. I usually shift at 1800rpm and am at 1000-1200 rpm in the next gear. The fact that I can get into 6th at 30 and that 80mph is @ 3000 rpm tells me that 6th could have been very comfortably taller. Sure, being able to pull away in 6th is somewhat convenient, but downshifting into 5th isn't an onerous task and I would rather have an extra 3 mpg at 70-80mph.

As it is, my typical start is in 2nd gear and I skip straight from there to 6th. I'd say 99% of the time I'm skipping at least 2 gears in the run up from 1st to 6th. There's definitely room to make them taller.

I'd be open to getting a replacement 6th gear in a few years when the warranty's gone, as long as it was cost effective (and they usually aren't unless you put them in immediately and plan to keep the car for 5 years).

[L0U]

I don't know the ratio, but I'm shifting into 3rd at 10mph, using 5th as the speedo passes 20mph, and into 6th by 30mph. I usually shift at 1800rpm and am at 1000-1200 rpm in the next gear. The fact that I can get into 6th at 30 and that 80mph is @ 3000 rpm tells me that 6th could have been very comfortably taller. Sure, being able to pull away in 6th is somewhat convenient, but downshifting into 5th isn't an onerous task and I would rather have an extra 3 mpg at 70-80mph.

As it is, my typical start is in 2nd gear and I skip straight from there to 6th. I'd say 99% of the time I'm skipping at least 2 gears in the run up from 1st to 6th. There's definitely room to make them taller.

I'd be open to getting a replacement 6th gear in a few years when the warranty's gone, as long as it was cost effective (and they usually aren't unless you put them in immediately and plan to keep the car for 5 years).

The 7 speed puts out a crazy 155km/hr at 3000rpm. 335 bimmer does 150km/hr at 3000rpm.