E89 Z4 Track-ready Sleeper Build

Asbjorn

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Quick update on the build. Installed ground control camber plates today. They bolted right in with no problems at all.

929924137.jpg

I am still running OEM "M" camber values, until I have had more seat time, especially at my local track. I need the car to be somewhat forgiving until get used to the additional power. :tearsofjoy:

And speaking of power, the car suddenly started leaking boost with an audible hissing sound. We found that one of the vtt clamps had become loose for some reason. I have circled the problem in below picture.

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I have highlighted the issue to vtt, and ordered new clamps to attempt a quick fix. (edit, it later turned out that the other hose had burned a hole)

Finally I also ordered a new bumper with better cooling potential (hopefully). I am having it painted and installed next week. The next track day will show if beneficial or not.

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Asbjorn

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Root cause of boost leak and hissing sound found

The rear turbo charge pipe hose was leaking boost with a hissing sound due to the problem shown below. The material only lasted a few laps at the ningbo racepark. In VTTs defense it was a very hot day, and due to up-sized coolers the air flow through the engine bay may be limited compared to stock. As you know one of my vacuum canisters also melted.

Clipboard012.jpg


Here's the location of the hose

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To fix the leak we cut new hoses from heat resistant material (1.5 inch ID) and this time wrapped them in aluminum.

Clipboard01.jpg


Hopefully this will prevent the problem from happening again.
 
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fmorelli

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Sorry to see this happened. Aramid-based high temp silicone couplers can definitely help with this. They are rated between 500-550°F. As added insurance, wrapping the silicone with some reflective heat shield before clamping it up might provide a bit of additional protection.

Good luck and let us know how it goes! I'm waiting to see the post on other upgrades you have in flight :).

Filippo
 

Asbjorn

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Sorry to see this happened. Aramid-based high temp silicone couplers can definitely help with this. They are rated between 500-550°F. As added insurance, wrapping the silicone with some reflective heat shield before clamping it up might provide a bit of additional protection.

Good luck and let us know how it goes! I'm waiting to see the post on other upgrades you have in flight :).

Filippo

Agreed - The blue hoses I installed are rated at 535F and honestly feel exactly the same as the VVT types. It is not expensive and easy to source in China, so would imagine VTT already use this type of material? @[email protected]

In any case I highly recommend installing some kind of thermal insulation between the manifolds and the hoses if the car is to do any track duty.
 
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Asbjorn

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M4-style bumper not installed

Yesterday I saw the result of the M4-style bumper paint job. I however decided not to install the bumper for four reasons

- The color doesn't match. I don't think it is possible to match this color perfectly.
- The surface of the "PP" material looks cheap compared to the OEM material which is stiffer. It bubbles and looks soft. It is soft.
- There was no cover for the tow hook. The tow hook needs to be installed during track events.
- I don't really think the design, color and wheel combo of my car suits the M4 or even M sport bumper design. It is too aggressive and would fit sporty colors (eg yellow) and sporty wheels much better.


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Asbjorn

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Latest steps towards combating high coolant temps and raising engine oil temps during track sessions

1) Smaller FMIC

Since I am only running 19psi, and measured iat levels are fine on track, I decided to swap to a smaller locally sourced FMIC that does not cover the CSF coolant radiator. I hope this will improve flow to the CSF radiator and keep the coolant temperature from reaching 116C after only two laps at Ningbo racepark.

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2) Better air ducting to aux engine oil cooler

Based on advice from Berry, I decided to have an air duct made from aluminum to facilitate better airflow through the aux oil cooler.

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3) Removal of decorative bumper elements

I think this picture explains why this may help

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The result:

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This looks pretty awful, but I will deal with that after I have determined if it helps or not.


4) New fluids

Finally I have swapped to Pakelo Krypton Racing 0W40 engine oil and bought some R+ Racing "Ultra Racing Coolant".
 
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Asbjorn

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Finished another track day at Ningbo Racepark

Completed two 25min sessions - no half check engine light, no DME codes - great day!

proxy.php?image=https%3A%2F%2Fi.imgur.com%2Ftd58hZ2.jpg



Video from the first session. Had a bit too much air in the front tires.



Video from the fastest lap I did during the second session (2.11.6)



Some of my mistakes



Engine ■
Still love the GC lites, the M4 flywheel and the BQ tune. BQ is currently updating my tune due to recent hardware changes (smaller FMIC, OEM catted downpipes to pass annual inspection). Unfortunately the updates were not ready for the track day.

Brakes ■■■


100% satisfied with the brakes after swapping to PB race pads.

Handling ■■■
I added around 1.5 deg camber up front, so the car now has almost the same camber front and rear. I believe the rear is 1.8deg. The car now feels more balanced, especially with less tire pressure up front. Less weight transfer / lower center of gravity would always be nice, but the car is already at the limit of being comfortable enough for road trips, so I will keep it at that and work on my skills instead. (Edit: it later turned out I had used threadwear 240 tires up front while rears were 180, otherwise same brand and type. After further driving, I also decided I had to do something to improve high speed stability).

Here is now my time compares to others I have on record at Ningbo Racepark.

2.03.92 - 488 spider
2.07.42 - 458 speciale
2.07.51 - 911 GT3 RS
2.11.60 - sleeper Z4... ie the time I set
2.12.26 - M2 (using slicks)
2.14.37 - Cayman GT4 (cup 2 tires) - however this car can do 2.04 when driven by a pro driver
2.15.19 - M135i pure stg 2 430hp (PS4 tires)


Cooling ■□□

I ran MHD track cooling during the first session, but forgot to log. It went quite well, so during the second session I ran stock cooling to see if it would work. Here's the log from the second session. Ambient temp was around 100F

https://datazap.me/u/asbjoern/ningbo-speedpark-session-2

With MHD track cooling enabled the engine cools down more during cool down laps, which means every second lap can be a full hot lap. During the second session I only did one full hot lap, and hit +118C coolant before the end of it, which meant the car entered component protection mode and reduced A/C. In the video above you may be able to tell that power was slightly reduced on the last straight before the finish line. This did not happen during any of the four hot laps during the first session with MHD track mode on.

In conclusion
- MHD track mode is useful during cool down laps.
- Downgrading from VRSF race to 7in nonHD FMIC added around 10-15C to my peak iat. This does not seem to be an issue.
- Engine oil temp peaked at 140C which is probably a non-issue. (component protection starts at 148C).
- Transmission temp peaked at 101C which is also a non-issue
- Coolant temp is doing slightly better than with the VRSF race FMIC installed, but this may just be down to changes in weather.
- During a 100F day, with A/C on high, the CSF coolant radiator is still too small. The car needs an aux coolant radiator. There is however no space for it.

I have yet to try the R+ Racing Coolant I bought.
 
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Asbjorn

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Very nice. Progress for sure, right? Headed in the right direction. Thoughts on next round?

Glad to hear you are liking the CG 2.0 lites! @[email protected] ... a little track time is a good thing for products!

Filippo

Progress for sure! Build is almost finished. Last challenges

- Get the BQ tune finalized (easy)
- Learn to live with the NVH of the M4 flywheel and poly diff bushings (also easy)
- Figure out how to make the front bumper look nice without the stone protectors etc (not very difficult)
- Figure out how to bend the shoulders of the sports seats inwards half an inch or so. This for better support and so they don't rub against the loudspeakers. (Difficult)
- Figure out how to improve coolant cooling. Honestly I struggle a bit on this one. Thinking about contacting CSF. Obviously there's also the PPK kit, just not sure if it is enough. Anyone have data from the 1 M coupe?

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Asbjorn

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Gain some weight - that will help the seat fit better.

Stone protectors just snap in - right?

Believe it or not, I ended up swapping the OEM seats back in.

ddd.jpg


Below are the pros and cons of the sports seats, and the reasons I decided to get rid of them again.

ProsCons
Communicates better (road feel etc)Communicates better (less comfort)
They look greatThey look newer than the rest of the interior
You don't slide around when pulling +1GsThey are a hassle to get in and out of
Allow for four point seat beltsThey hurt your back during longer trips
Lightweight They rub and rattle against the rear loudspeaker
Headrest does not rub against your helmetNo seat heating (vital in a convertible car)
No one can tell they are not OEM seatsNo adjust-ability, only suits one driver
[THEAD] [/THEAD]
[TBODY] [/TBODY]
One of the main reasons I installed the sport seats was to be able to use four point racing harnesses. The reason being that the track I used to visit required passengers to wear those. I since moved to another city in China, and no longer visit the track that had this requirement.

Ningbo Speedpark don't care what seat belt you use, but require the top to be up when on the track. Guangdong Circuilt require 4 point racing harness for passengers only, but do not require the top to be up.

In short, the sports seats were great 1% of time (ie on the track), and then a pain in the back the remaining 99% of the time. I quickly realized this, but due to the efforts of having them custom made etc, I just couldn't really admit it to myself.

So to conclude, I have now gone back on the following items

What disappointed meWhat I installed insteadWhy
Custom sport seatsOEM seatsBetter 99% of the time
NVH from M4 dct flywheel when under load at low rpms in high gearsStill using itUsing DCT S or M-mode eliminates the problem
NVH form diff poly bushings (edit: this turned out to be bad diff bearings instead)Still using themProvide better drive train response, hard to replace, sound race-car-ish (edit: sound disappeared after replacing diff)
Custom-made race-catted down pipesNew OEM-type down-pipesCould not pass annual emissions inspection with race-catted down-pipes.
M4-style bumper with larger air-intakes for both oil-coolersOEM bumperColor didn't match. Looked bad. Destroyed the sleeper-look. Oil cooling not the main challenge at this point (coolant cooling is).
VRSF race HD FMIC7in nonHD FMICThe VRSF race FMIC was overkill for GC lites running 19-20psi, even on the track in 100F heat (iat peaked at 75C / 167F).
VTT alu charge pipe couplers that started leaking due to over-heatingVTT alu charge pipe with new couplers and custom alu heat shielding Only solution available for GC lites
CSF coolant radiator Still using itNo better options. Still insufficient cooling capacity on the track in 100F heat
EBC yellowstuff brake padsPB race padsYellowstuff is apparently only suitable for lighter cars if used on the track (ie cars weighing well under 3000lbs)
[TBODY] [/TBODY]
 
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Asbjorn

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Two challenges remain towards the finalization of the build
1) Improving coolant cooling
2) Car is a bit difficult to place precisely above 90mph or so

As for challenge number one, I am swapping to R+ Racing coolant tomorrow to see if that helps.
As for the second challenge I would like your input. @fmorelli suggested @[email protected] might have an opinion on this? The problem can be seen in below video just before the braking zone.


I almost touch the grass as the car "overshoots" to the right at high speed. It was not my intention to get this close to the grass, but the car corrected with a larger delay than expected at this speed. I do not have this problem at lower speeds.

Something similar happens if you skip to the 1min mark in this video and watch how the car moves while braking above 80mph


Now my question is, what is the root cause here? I would assume it is related to weight transfer, but how do I best amend the problem?
1) By simply accepting it, and becoming a better driver instead?
2) By stiffening up suspension bushings? And in that case, which ones?
3) By stiffening up springs or dampers? (I certainly hope not)
4) By adjusting alignment?
5) By using stiffer tires?

This is how the car is setup now, and the sway bars are set to their stiffest settings:

recap.jpg
 
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derekgates

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I do not have much advice for your track 'troubles' regarding braking but I must commend you for your investigation of parts, getting rid of parts regardless of 'sunk cost' and the documentation of all of this work.

Really amazing job you are doing with this car! I am enjoying watching your trials and tribulations with the Z4 and how you investigate parts without caring 'how it should be done' (other than final looks). Man, I have a lot to learn.
 
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Asbjorn

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Stiffer springs

Ended up installing Eibach pro-kit 20/10mm to see if that has any influence on the "place-ability" above 90-100mph.

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I don't like how the car looks lowered like this, and I already hate how easy it bottoms out on bad roads, but it does feel more responsive at low speeds. Car feels awesome stiffened up like this. Much less squat and dive on braking and acceleration.

Alignment was quite difficult to get right, but we ended up with something similar to this.

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As a funny side story, the supplier send 30i springs by mistake, and we didn't realize until they were installed. Car was grounded for 5 days waiting for the right springs to arrive.

More problems with the VTT charge pipe for the GC turbos

BTW we also found that another vtt chargepipe hose was about to give up. It was gold tape wrapped and had held up longer than the non-wrapped hoses. We have now installed new ones and used aluminum heat shield like we did on the other hoses. This seems to be the only way forward. One of the heat shields are shown in the picture below. The vtt chargepipe for GC turbos needs three of these.

1015021062.jpg 1098495987.jpg
 

fmorelli

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More problems with the VTT charge pipe for the GC turbos

BTW we also found that another vtt chargepipe hose was about to give up. It was gold tape wrapped and had held up longer than the non-wrapped hoses. We have now installed new ones and used aluminum heat shield like we did on the other hoses. This seems to be the only way forward. One of the heat shields are shown in the picture below. The vtt chargepipe for GC turbos needs three of these.
If I recall you swapped in Samco 500°F silicone when you replaced the first? If you know which hose (p/n, URL) it might be handy for others to know.

Filippo