Recent track day results

[NoQuarter]

2011 Z4 35is

MHD OTS Stage 2+ 93 Oct map

Catless Downpipes
7" intercooler
Turbo inlets and outlet
Charge pipe with BOV
Stock suspension

Had 3 20min sessions at Gingerman raceway. This is a 2 mile track described as

"The course layout simulates the full spectrum of driving situations: high speed straights and short sprints, long sweeping corners and tight apexes, heavy and light braking, and elevation change."










The good news:

The car ran great with a few exceptions mentioned in a moment.
It was a sunny day with air temp 77-80 DegF.
Oil Temp climbed to 260 and came back down quickly
Burned no oil as far as I could tell from the iDrive display
The stock brakes held up just fine and this course is very hard on brakes.
I did not get a single limp mode, misfire, or codes of any kind

What could be better:

My rear tires chewed up my plastic rear wheel liner. I have the wheels pushed out but I didn't expect the rubbing to be so bad. Perhaps my liners are not installed correctly and sit too low?

I am just a novice driver so I'm sure I had some terrible technique, but I can also see the desire to improve the suspension on this car. At turns 3,4,5 and 7,8,9 felt like the car was all over the place when switching directions.

The not so good news:
This has me puzzled and I am interested in any thoughts you may have here.
Remember - No error codes of any kind and I did not try to log while in a 20min session

Turn 10B goes into that long straight where I could hit 120mph if the road was clear. Long sweeping turn, elevation to a blind hill then that awesome straight.

At around 100mph and accelerating, I would lose power in a surging sort of behavior. Things that seem plausible to me:

- Throttle closure but due to what?
- DCT slipping? Our DCT is rated a lot higher then where I am power wise right?

-Fuel seems most likely to me. I know I was low on fuel so possible fuel starvation? But, If the fuel sloshes away from the pump and the engine doesn't fire correctly that would get me an error code right?

[NoQuarter]

Thanks. That removes the DCT as a reasonable possibility.

I am more convinced this was a fuel problem but, if so, why no codes of any kind? I suppose if the DME handled the condition exactly like it was supposed to then no need for a code?

[Tangent]

I recently went to a track day at California Speedway and also had no trouble. Oil temps got a bit higher in the roughly 95* ambient temps but also came back down very quickly, and I also had no braking issues with the EBC Yellowstuff pads on stock hardware. I did notice something interesting when I checked for a code that appeared the next day though. The code that set the light was for an O2 sensor so perhaps the extended and repeated time at full throttle (I hit 140 mph by the end of the front stretch) with the MHD stage 1 tune was enough to euthanize that sensor. The interesting thing I saw though was a shadow code that said something about reduced power (which I never noticed) due to front brake rotor overheating. Of course our cars don't have actual temperature probes there so maybe it calculates rotor temps based on ambient temps, speed, and deceleration. Maybe yours actually did reduce power because of perceived brake overheating?

[NoQuarter]

Interesting about the brake temp warning. Something to try and read more about.

[jts1981]

Originally Posted by NoQuarter

This has me puzzled and I am interested in any thoughts you may have here.
Remember - No error codes of any kind and I did not try to log while in a 20min session

Turn 10B goes into that long straight where I could hit 120mph if the road was clear. Long sweeping turn, elevation to a blind hill then that awesome straight.

At around 100mph and accelerating, I would lose power in a surging sort of behavior. Things that seem plausible to me:

- Throttle closure but due to what?
- DCT slipping? Our DCT is rated a lot higher then where I am power wise right?

-Fuel seems most likely to me. I know I was low on fuel so possible fuel starvation? But, If the fuel sloshes away from the pump and the engine doesn't fire correctly that would get me an error code right?

What mode were you in, sport +? You may have experienced the dme pulling back power to avoid slip. I experienced this feeling when I was at M school.

On a side note, are you running stock air box + filter? I would recommend going with some sort of cone set-up, especially since you have inlets and outlets. The stock air box is a choking point. If you open the air box you can see all the air flow is limited to very small openings. I don't think you are able to take advantage of the inlets/ outlet with oem box. I went through this when I dyno'd my car after inlets. The gains were minimal due to stock airbox. After switching to AFE dual cone the car felt MUCH better. Anyways just some food for thought.

[rif75]

Originally Posted by jts1981

What mode were you in, sport +? You may have experienced the dme pulling back power to avoid slip. I experienced this feeling when I was at M school.

On a side note, are you running stock air box + filter? I would recommend going with some sort of cone set-up, especially since you have inlets and outlets. The stock air box is a choking point. If you open the air box you can see all the air flow is limited to very small openings. I don't think you are able to take advantage of the inlets/ outlet with oem box. I went through this when I dyno'd my car after inlets. The gains were minimal due to stock airbox. After switching to AFE dual cone the car felt MUCH better. Anyways just some food for thought.

Hey JTS,

Just ordered the KW V3, what settings are you running on street and track if you go on it?

Did you see a real difference with the HR sway bars? Not loosing too much in confort?

Thank you