S4 K04 Conversion

[Nige_RS4]

Shaun, how would you describe the change in lag (if any) from your K03 car - does the torque come in later (but harder)? The one thing I like about the S4 over the RS4 (well the one I test drove) is that it kicks in earlier?

Cheers.

[Prawn]

OK, Compared to the k03 with AMD remap.

Below 3~4K revs the car feels simular, ie roughly the same lag but with more go.
Above 3K5 it really picks up and almost starts to howl.
The tourque curve now is higher at all points that it was with the k03's but the big difference in the plot is from 4K on.
Ko3 max tourque was around 3K5, for the ko4 it is 4K, however the tourque from 4K is approx +100lb/ft over the k03 + remap figure all the way to the red line.
My personal feeling is that the car is now much better, smoother and more linear in the way it delivers the power.
With the k03 + remap the 'hit' when the boost came in at 3K+ was quite noticable.
Now the power feel very linear all the way from 2K up with no real perceptable boost hit just a never ending increse in momentum.
The only exception to the above I would say is in 1st gear, if you nail it now in first you don't have time to get your feet to react quick enough before you hit the limiter !

I have also test driven a std RS4, IMHO the ko3 + remap felt better to drive than the std RS4 however the K04 S4 feels better again with better response time and way more push.

[Nige_RS4]

Damn! Kinda wished you hadn't said that, as I'd been telling myself that I would lose some of the low-down grunt and have more lag etc.. will have to start saving !

BTW, did you fit an uprated FRP or RS4 fuel pump ?

Nige.

[SJS]

The manifold must play a fairly important part in the available power, cos if you look at the AWE site they are claiming 418hp and 512ftlb and all of that is on just 93 octane fuel, just imagine what it would be if they used Optimax with millers

That 93 octane is american octane rating, which roughly equates to our 98 octane. However adding millers would make a slight difference.

[Prawn]

HI Tweaky,
K03 + remap was giving me 329bhp and 381lb/ft, however I only had the cat back Miltek at the time.
IMO the main benefit of the K04's s that it flattens the tourque curve, especially over 4K.
512lb/ft sounds good, I would not have thought that the manifold would give an extra 60lb/ft, I should think there are other mods as well.

[Dippy]

The one thing I like about the S4 over the RS4 (well the one I test drove) is that it kicks in earlier?

From what I've seen of S4 with K04 remaps is that there is no noticable extra lag. The lag from the RS4 really comes from the cams which are tuned for high rev power (and which is why a tuned RS4 can go well above 400 bhp).

...however the tourque from 4K is approx +100lb/ft over the k03 + remap figure all the way to the red line.

Precisely the advantage of the K04s - not only increased boost, but the increased air flow rate allows it to be maintained at higher revs.

It is a shame that you only had the catback for your K03 setup - the freeflow cats really give an extra dimension to a K03 remap.

That 93 octane is american octane rating, which roughly equates to our 98 octane. However adding millers would make a slight difference.

Actually I think 92 US is more equivalent to 98 RON, so 93 US is even higher.

512lb/ft sounds good, I would not have thought that the manifold would give an extra 60lb/ft, I should think there are other mods as well.

I can't get to the AWE site now (company firewall), but it looks high to me too. In general the tuners quote 'ideal' figures and we should always expect less from our cars. I'd bet that the test car had other tuning.

In regards to the exhaust manifold, remember that in itself, no exhaust modification can increase engine output - that is all done from inlet and engine modifications. Exhaust modifications are done to reduce backpressure on the engine, so that effectively the overall engine efficiency is improved.

Furthermore you need to be careful with exhaust mods. If the exhuast gasses flow TOO freely, then torque can actually be reduced in parts of the rev range. In general exhaust mods improve gas flow to increase top end power, and the trick is to achieve this without affecting bottom-end torque.

I would say that if you are having K04s fitted, then exhaust mods are a must, including the manifolds (assuming that the claims are true) even at £1K. Otherwise you are paying a lot of money and not releasing the full potential.

Having said that I am still unlikely to do this mod myself. It's got to cost at least £5K all in, and that's a serious dent in the cost of a next-generation RS4!