Kick gone at 5.5k revs

[Lig]

Interesting, I would deffo relate it to a turbo type surge - There is something deffo wrong if you can't feel it.

Every time I hit 5300 ish revs its kind of a 'wooahhh - tighten your grip on the steering wheel' moment.....

Lig.

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The intake tumble flaps goe from tumble/closed to open at 3k rpm.
5.5k rpm is when the airbox power flap opens (debatable how much effect this has), the 1-3 torque limiter is removed and the cam profile is changed to power from economy and timing advanced more.
I would also imagine the ecu map is more power oriented than economy so that would also have some effect.

I personally don't like the kick - I want full power when I press the pedal down not an artificial rpm limit. When I used to have the 5.5k kick (don't have now as it's been tweaked for power everywhere) I always found it depressing as it's like the engine saying "look what you could have had lower down".

[mac911rs4]

don't tell me that....my car's under a long warranty and i'd love to get it tuned, even more so after reading your post, just cannot void that all in warranty !! or could i ?
thanks
m

[sakimano]

The intake tumble flaps goe from tumble/closed to open at 3k rpm.
5.5k rpm is when the airbox power flap opens (debatable how much effect this has), the 1-3 torque limiter is removed and the cam profile is changed to power from economy and timing advanced more.
I would also imagine the ecu map is more power oriented than economy so that would also have some effect.

I personally don't like the kick - I want full power when I press the pedal down not an artificial rpm limit. When I used to have the 5.5k kick (don't have now as it's been tweaked for power everywhere) I always found it depressing as it's like the engine saying "look what you could have had lower down".

I agree...I hate that an RS car has a torque/throttle limiter. What's the point? GET RID OF IT!

Must be to protect the car in some way. Still...it's a damn RS model...and there's even a SPORT button you can press to go even further than a normal RS.

How on earth they don't open the taps up all the way from 1 RPM in 1-2-3 when SPORT mode is engaged I will never really understand.

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Official line is to protect the drivetrain.
But i suspect a bit of daylight required between rs4 and r8 from a marketing point of view.

[gareth_oau]

sorry, duplicate post

[gareth_oau]

its nothing like a turbo kick, especially if you are used to old-school turbo lag, but its still noticeable AND enjoyable.

Its more like the VTEC kick that Honda exploited in their marketing when VTEC first became popular

[gareth_oau]

its nothing like a turbo kick, especially if you are used to old-school turbo lag, but its still noticeable AND enjoyable.

Its more like the VTEC kick that Honda exploited in their marketing when VTEC first became popular

[adsgreen]

Agree it's similar but Vtec kick is horrible - its progressed a bit but the difference between the cams and the engagement parameters made for a royal pita on track.

But turbo lag is a side effect, this kick is nothing more than a design decision and the car is worse for it.
Hell you get the same effect by only using 3/4 throttle up to 5.5k Ron then mashing it.
Why would you want such shackles on?

[ArthurPE]

thanks, interesting data
3k to 5k you have ~ 390 Nm
pretty close to the peak of 400 at 5.5-6k, less than 5% more
I don't think limiting the throttle below 5.5k limits power, in fact the opposite, the engine turning at lower rpm doesn't need as much air since Q ~ displacement x rpm
if you look torque is ~390 up until 5k or so, and only then does it begin to trail off (due do lack of Q and/or pressure drop due to the increased velocity, ie, squeezing air thru a smaller opeing increases velocity ~ pressure drop), and this may be a result of the flaps moving/disturbing flow, as much as the increase area...
after opening it only peaks ~400...which tells me the engine is damn near optimized under hi/lo rpm conditions
it would be interesting to see this data on a de-flapped car, torque imho would go down <5k rpm
imo the intake flaps optimize flow below 5k becuase volume is low, hence velocity is low, and above due to due the increased volume are not required

I can do that for you using my pbox. If you just go download the performance box software from racelogic's webpage, you will be able to play with the file and can move the cursor to see the data all the way along (and the data includes dozens of things...speed, time, elevation, long. G, lat G, etc..
I can also just post a chart for you in image format...but I thought you'd like to have the data at your hands.

I think it's a few things...intake adjustment, cam profile and of course the airbox flap opening...as well as (most important I'd bet) the torque limiter in the stock ECU file being lifted at 5200 RPM or so. You can see that in my log below...throttle is heavily restricted in gears 1, 2, 3 (52%) up until the 5000-8000 range:

[ArthurPE]

its nothing like a turbo kick, especially if you are used to old-school turbo lag, but its still noticeable AND enjoyable.

Its more like the VTEC kick that Honda exploited in their marketing when VTEC first became popular

I have a 1986 951 (944 Turbo) and THAT has turbo kick, lol

[adsgreen]

its nothing like a turbo kick, especially if you are used to old-school turbo lag, but its still noticeable AND enjoyable.

Its more like the VTEC kick that Honda exploited in their marketing when VTEC first became popular

I have a 1986 951 (944 Turbo) and THAT has turbo kick, lol

ha ha - yes! most definately!
However that usually went chug chug Whooosh! Hedge.

[mac911rs4]

yep, car had a blast tonight, down through brands and back up the A20 and i can honestly say, phew, seems to be working perfectly, although i have to agree with some, not as course as a turbo rush, would be nice, but i'm happy with that hard working lump under the bonnet any day of the week, through all the gears, heaven.

[sakimano]

arthur - here`s a chart of the longitudinal acceleration in g from my pbox

speeds are roughly 40 to 95...which is most of the rev range you requested. Speeds are GPS based bear in mind, so more like 42 to 100 on the speedo.

edit: hold on..won`t let me upload an XPS file. I`ll figure out how to convert it to an image

edit again: got it





here`s another slightly odd one...big spike



Both were on 60-90 runs I was using to compare a couple of cars. Here`s a B8 S4 bone stock manual transmission on the same stretch of road. Identical to the RS4 with both cars running 4.38 seconds from 60-90

[ArthurPE]

thanks!
perfect
if in 3rd gear 5-6k is ~ 60-72 mph
peaks are at (guesstimating a curve fit)
70-80, pretty small ~ 0.02g or less, imperceptable
80-85, a bit larger, ~0.1g+, I'd say a measurment anomoly

looks like the RS4 has a more consistent thrust, which is impressive considering that the S4 is supercharged which manipulates torque production
if we look at 60-90
RS4 avg g ~ 0.325 to 0.275
RS4 2nd graph, pretty much the same

S4 0.275 to 0.26 or so