JHM Stage 1 Supercharger Dyno

B6/7 S4/RS4
#61

Thanks for the reference… I can see a slight difference between both, the rs4 is pulling a little harder on the tach… that’s not crushing it tho…

#62

What’s the weight difference between the S4 Avant and RS4 Sedan? Whatever it is, add on top of that another 130 lbs. (So if the difference is 100 lbs, the final difference would be 230 lbs). Might be enough to cause a difference on a low rpm 6th gear pull. Not sure though.

#63

I think avants are 150 heavier

Also dont forget that 1 rpm does not equal 1 rpm s4 vs rs4

#64

ERRONEOUS!!! hahaha

#65

how’s that?

#66

Gear ratios for the curious

B7 S4
1st: 3.667
2nd: 2.050
3rd: 1.462
4th: 1.133
5th: 0.919
6th: 0.778
Final Drive: 3.889

B7 RS4
1st: 3.667
2nd: 2.211
3rd: 1.520
4th: 1.133
5th: 0.919
6th: 0.778
Final Drive: 4.111

Stock s4’s wheels are 235/40/18 (I think)
Stock rs4s are 255/35/19

#67

Just messin with ya and being a troublemaker. One revolution is one revolution no matter what engine you are talking about. The products of that revolution can vary drastically which I know is what you are talking about.

#68

Interesting, so only 2nd and 3rd are different. Although with the extra 1000rpms, does that mean they end up pretty much at the same velocity at redline?

#69

I assume that already takes into account the spare tire + jack.

So rear cargo cover (30lbs) + Roof box (60lbs) + 30 lbs of crap in my trunk + 150 lbs difference between the cars = a whopping 270 lbs difference.

#70

well avants vs sedan both have spare etc so it doesn’t matter. rs4 doesn’t have a spare…but it weighs the same as a b7 avant so again moot

#71

All other things assumed to be equal as well, if you are in the same gear with the same ratio and the same engine RPM you should have the same velocity. But there are a lot of other things to throw into the mix that will determine actual observed velocity.

#72

Well obviously they don’t have the same ratio. If the RS4 had the same redline as the S4, it would hit the top of second at an earlier velocity than the S4. However, due to the extra 1000 rpms, I’m wondering if the RS4 ends up hitting the top of 2nd (and 3rd) at more or less the same velocity as the S4.

#73

So in your original “I think avants are 150 heavier” did you mean the RS4 Avant is 150 lbs heavier than the RS4 sedan?
Cause if you meant the S4 Avant is 150 heavier than the RS4 sedan, you’re contradicting yourself by then saying that the “rs4 doesn’t have a spare but it weighs the same as a b7 avant”.

I know the RS4 doesn’t have a spare. I was basing my comment on your original statement that Avants were 150 heavier (assuming you meant S4 Avant seeing as that’s what we’re currently comparing to) and assumed the 150 difference already included the difference with the spare tire and jack situation. In other words, no point in adding that to my calculations because it was already taken into account.

#74

If you compare 2nd gear:

**EDIT: fixed my shitty math
RS4: 8000rpm (1/2.211)(1/4.111) = approx 880 rpm at the wheel

S4: 7000rpm (1/2.050)(1/3.889)= approx 878 rpm at the wheel

Then factor in wheel size…

Close.

#75

For fun:

http://www.kabamus.com/garage/gears.html

According to this calculator the difference in 2nd gear at redline would be less than 2 mph in the favor of the RS4. (68.15 over 66.35)

#76

i meant what i said…avants are 150 lbs heavier than sedans. That’s the weight premium approximately for an Avant over the same model sedan

RS4 weighs about120 lbs more than an S4.

So RS4 sedan is really close to S4 Avant weight.

#77

Ok, thanks for the clarification.
So if they weigh approximately the same, I’m about 100-120 lbs heavier with my box, cargo cover and junk. Not a huge difference.

#78

My RS4 weighed 3940. 1790 KG with a full tank.

Mistro probably weighs about 15-20 more because he has the premium package, and it has a couple of things like memory seat module, sat radio module, and the surprisingly heavy rear window automatic sunshade. So he probably weighs, stock car with full gas, about 3960.

B7 S4 sedan weighs around 3850. B7 S4 avant weighs around 4000 flat. So you’re 40 lbs heavier to start, then the variables like your roof box and the shit in your car, and whoever had more fuel etc.

Anyway, nobody has mentioned the speedo rate of increase yet…was it the same or different? Just heard a couple of rpm comments but what about the speed?

#79

Is that like speedo error? Or dV/dT?

#80

After all that, it’s tough to say and I’d call it pretty even overall. In other words, we’re really just wasting Internet space lol