E89 Z4 Track-ready Sleeper Build

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Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
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
Just get the original vvt ones if you are based in the US. They have confirmed it is already the high temp type.

I got the type I use now from a local chinese taobao shop because it took too long to get them from vtt. Brand was random. Shop even said I could choose custom color and logo if I wanted. Anyhow ID is 1.5in if you want to source it yourself. Think I paid 10usd for 1m.

The main point is they need heat shielding for track use in my experience. All three of them. Gold tape is not enough. Or maybe it is just my car due to upgraded coolers and less airflow through the engine bay? I mean... my canister literally melted. That never happened with stock coolers and stock turbos.

If you haven't figured it out by now, you absolutely need aluminum charge pipes/outlets.
Yeah and the problem is the GC series. They still connect with silicone hose clamps even the rest of the charge pipe is aluminum. See the difference below.

Aluminum%20Outlet%201-228x228.jpg
 

fmorelli

Colonel
Staff member
Aug 11, 2017
2,458
Virginia
As far as I know there are three high temperature ratings for silicone couplers. 350, 500, 550 degrees Fahrenheit. Not sure what vtt is using, but I would be amazed if you melted 500-degree coupler!

Filippo
 

Itsbrokeagain

Corporal
Jan 28, 2018
166
Strong Island
Regarding your temps, is there any reason you must have the AC on? Is it personal preference to leave it on? Im pretty sure no full on race car has it (most drivers wear a cool suit or sweat it out), and that may be contributing un-needed strain on the cooling system.
 

Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Regarding your temps, is there any reason you must have the AC on? Is it personal preference to leave it on? Im pretty sure no full on race car has it (most drivers wear a cool suit or sweat it out), and that may be contributing un-needed strain on the cooling system.
It is funny you asked. I recently went to a circuit in China were they allow you to drive with the top down. There I did try running with the A/C off and heater on max temp medium fan. I of course also ran the two additional oil pumps/coolers. Now unfortunately I did not log that day, but I am pretty sure the highest oil temp I saw was 135C. I went through my video material, and that seems to be right. This is an improvement, because it was a very hot day, and I would normally see 140C after similar hot lapping. The car also seemed to hold up a little better than my friends M135i with stock cooling running pure stg 2 at around 14 psi. He was, very understandably, running with the AC on (until it was reduced by the DME due to high temps). He actually told me he got a warning in his dash.

Anyhow, after just a half an hour session like that, my race suit was done. The parts that were not already white, had turned white due to salt. It was a small improvement to my car's temps, and a huge disadvantage to my own haha.

And as I understand, the reason full on race cars don't even install ACs, is that it reduces power just by being there, even if you do not turn it on. But you know, those cars are delivered to race tracks on flat beds, and you pee in the seat during a races and stuff like that. It is just a different level of seriousness. I was aiming for "track-readiness" with this build, and would rather add an extra cooler, than having to take a shower after each track session. Something similar to what BMW has done with the M2 where they added a bit of extra cooling, some additional oil sump management (for the extra Gs on track) and stopped. In the end, I also need those cool down laps to evaluate and re-focus to avoid loosing concentration and making (more) stupid mistakes. If gokarting has taught me anything, that is certainly one thing.

Anyhow, everything will be better once temps drop below 100F.
 
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Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Quick update on the (allegedly) finished build

#1 Since my differential bearings went bust during the grand track tour of China, I bought a used diff from a scrap yard, and is currently having the old Quaife core reinstalled in the new diff.

2053506357.jpg



#2 At the same time we are installing bimmerworld solid subframe mounts

1757515485.jpg


1439011554.jpg


I am hoping this will lead to better stability and predictability of the rear end when driving at the limit.

#3 We are also installing bearings instead of the M rubber compounds on the front tension struts.

1502247829.jpg

What came out

1639887242.jpg


Hopefully this will also lead to better stability and predictability when driving at the limit. We went with this sealed unit instead of the nicer looking AKGs. BimmerWorld Part #: 100.31.582.0006

I will report back if NVH is not tolerable with these mods.

#4 finally I am swapping in the n20 tmap sensor to get rid of an occasional 2ABC code. Apparently it might also help us increase and sustain boost throughout the RPM range.

311378589.jpg
 
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Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Since this is now a five page thread, I decided to update the first post with a summary of the build with links to relevant posts.

When making the summary, I realized I never made a dyno plot. Since this is actually possible with the virtual dyno windows application using mhd logs, I decided to make one.

According to this program, peak power sits somewhere around 430-440hp at the crank. This is probably right, as the car is slightly faster than an M4 from 100-200kph. But what is more interesting here is the torque curve, and how flat it is. In this graph, wheel torque is 450nm +/- 8% from 3200rpm to 6400 rpm.

current-power.jpg


Now this is based on the current setup with 7in FMIC and OEM catted down-pipes. For fun, I made a comparison to when I had race-catted down-pipes and 7.5 HD FMIC (Red curve). Please note changes to the vanos tuning etc was made by BQTuning after changing the hardware.

v7-vs-v13.jpg


What I see here is faster spool with race-catted down-pipes installed. However peak power is the same.

The torque curve is also flatter with the OEM catted down-pipes, which is actually better at the track. So the main disadvantage is slower spool and less power below 4500 rpm. This is not really a problem at most tracks, as the speed and rpm is typically high, but I did feel this disadvantage during the final corners of this very small track which is basically part of a go-kart circuit. Of course it can also be felt on the street, but given the power, this is not an actual problem.

I didn't intend to run OEM down-pipes when I started this build, but given the improved sound and flatter torque curve, it is not actually that bad. Now as for the sound, please keep in mind I already run de-catted mid-pipes, so with all OEM cats away, the car was a tad on the loud and raspy side. To put it in other words, it sounded faster than it actually was with the race-catted down-pipes, whereas now, it sounds a bit slower than it actually is.
 
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Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Quick update on the build's cooling performance in cool weather. I went to one of the tracks that caused my coolant to exceed 117C (243F) on a hot lap when it was 100F outside. I pushed around 70% of what I did at that time, and logged for 10mins. I only pushed 70% because the track was damp and covered with leaves from yesterdays rain. Rear was sliding around quite a bit. Anyway, the resulting 10min log is linked below.

https://datazap.me/u/asbjoern/bq-v18-track-session-shanghai-tianma-10mins?log=0&data=2-5-13-20-28&solo=13

Results
Peak iat: 46C (115F) towards the end, as I dared to go faster
Peak coolant: 99C (210F) at the very beginning, then settled around 200F
Peak transmission: 77C (171F) at the end
Peak engine oil: 126C (259C) towards the end

Other
Ambient: 17C (63F), damp track
Front tires: 50-60C (122F - 140F) at the end

Setup
MHD cooling setting: Stock
Climate control: Heater on max temp, slow fan
Transmission cooler: ON
Engine oil cooler / semi-dry sump: ON
Other: Intake snorkel removed, top down

Conclusion: In cooler weather, when pushing only 70% on a very tight track, the car barely gets up to operating temps. Only the brakes really had to work for it.
 

Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Quick update on the (allegedly) finished build

#1 Since my differential bearings went bust during the grand track tour of China, I bought a used diff from a scrap yard, and is currently having the old Quaife core reinstalled in the new diff.

View attachment 16647


#2 At the same time we are installing bimmerworld solid subframe mounts

View attachment 16646

View attachment 16643

I am hoping this will lead to better stability and predictability of the rear end when driving at the limit.

#3 We are also installing bearings instead of the M rubber compounds on the front tension struts.

View attachment 16644
What came out

View attachment 16645

Hopefully this will also lead to better stability and predictability when driving at the limit. We went with this sealed unit instead of the nicer looking AKGs. BimmerWorld Part #: 100.31.582.0006

I will report back if NVH is not tolerable with these mods.

#4 finally I am swapping in the n20 tmap sensor to get rid of an occasional 2ABC code. Apparently it might also help us increase and sustain boost throughout the RPM range.

View attachment 16642
So a quick long-term review of the above

1) n20 tmap - the o-ring cracked causing a boost leak. Swapped o-rings 900 times until finally installing the oem o-ring from my original tmap. Did smoke testing and vacuum leak testing. Everything finally seems to be back to normal.

2) Ball bearing kit for tension strut arms. So all rubber is now removed from the front suspension (except the tires). Steering is razer sharp. So is the harshness on bad roads... Keep the OEM strut bearings and M tension strut rubber if you do not like a harsh ride. Only do this if 1) incredible steering feel means everything to your, or 2) you go to the track all the time.

3) Solid subframe mounts. These feel awesome on the track, but vibrations from road and exhaust are increased. The OEM subframe bushings must have been really soft, because removing those has made a bigger difference than changing any of the other bushings back there. The rear of the car just loads up instantly, and you can feel it on acceleration and braking as well. It makes the car more fun to drive. I understand why the M cars are like this from stock. However on a street Z4 you would probably want to go with upgraded subframe mounts that are not solid to reduce some of the road and exhaust vibrations that come with solid mounts.

4) Quaife reinstallation. This product is still awesome, and I am happy my diff whine is gone, now that I have a differential with good bearings. However, it was fun to feel how the car behaves with an open diff again - the quaife really makes a difference in how smooth the car transitions from sliding to grip. It also makes the rear feel more planted on corner exit when at the limit of traction.

In other news, I am currently in the process of dialing in the right amount of camber. Please visit this thread for details.
 
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InnovativeAuto

Specialist
Mar 14, 2018
63
Can you tell me more about the wheels? I have never seen a forged replica 293 and cannot find any. I would like to get a set myself.
 

doublespaces

Administrator
Oct 18, 2016
7,763
AZ
- 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?
The OEM PPK aux radiator is the same core as the oem oil cooler. I have this installed as a transmission cooler and the core is incapable of stopping the temps from rising while parked and while on the road, temps don't even out until over 200 F. I do not recommend using the OEM core, the ducts are meh also. The OEM parts are actually flimsy and feel like an after thought not to mention trying to source them is difficult.

If you want to increase your engine cooling and you weren't afraid to rip things apart and try again perhaps you could ensure you're using the Manual CSF which does not have the transmission heat exchanger circuit and also move the transmission cooler away from your radiator and put the engine oil there since those temperatures are linked.
 

Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
The OEM PPK aux radiator is the same core as the oem oil cooler. I have this installed as a transmission cooler and the core is incapable of stopping the temps from rising while parked and while on the road, temps don't even out until over 200 F. I do not recommend using the OEM core, the ducts are meh also. The OEM parts are actually flimsy and feel like an after thought not to mention trying to source them is difficult.

If you want to increase your engine cooling and you weren't afraid to rip things apart and try again perhaps you could ensure you're using the Manual CSF which does not have the transmission heat exchanger circuit and also move the transmission cooler away from your radiator and put the engine oil there since those temperatures are linked.
Thanks for the suggestions. I wanted the larger DCT cooler due to inspiration from the MS division. The M4 GT4 uses exactly the same coolers as a stock M4 except for one - the upgraded DCT cooler, which was taken from an M6. I guess the delayed heating of the DCT oil only really shows on track.

Now what you didn't know is that I already had an additional radiator custom made during December. It finally went in yesterday just in time for my response to your post haha. Turns out having a radiator made to spec costs next to nothing in China.

I also upgraded engine oil cooling and brake cooling just because why not. Let me go though each of the upgrades below:

New additional coolant radiator
*) Almost same total cooling area as the stock radiator. One pass radiator without DCT heater core. Connected in parallel to the CSF unit.
*) Keeps the DCT heating function intact because the CSF AT radiator is untouched. DCT track cooling is still handled by the separate oil cooler and pump.
*) Additional radiator sits in front of the condenser unit, and behind the DCT cooler with large air gaps on all sides, allowing fresh air to pass around it. Time will tell if this location works, or if the unit has to be placed somewhere else for the AC to work on hot summer days.
*) R+ racing coolant replaced with OEM coolant for increased longevity and lower cost.

1683588516.jpg


Additional pictures:

1216933566.jpg 1994814122.jpg 113731285.jpg

Upgraded stock location oil cooler
*) Around twice the area of the stock unit. Around twice the depth as well.
*) Stock unit completely removed. New unit Installed directly to stock thermostat housing using adapter.
*) Semi-dry oil sump and associated oil cooler untouched.
*) Considering to replace the 95C thermostat with the OEM version to keep oil temps above 100C/210F on high ways.

61898073.jpg


805932809.jpg

Air scoops for brake cooling ducts
*) Intake raised to FMIC height to decease risk of scraping and increase longevity.
*) Air scoops added to increase intake area (the scoops were taken from a W212 Mercedes air intake)

1048522247.jpg

End result

1665060716.jpg


With the OEM bumper in place, everything still looks completely stock. Now all I need is some hot weather so I can start logging.

BTW @doublespaces since the site upgrade, the tables I made in post number 1 don't work anymore. Is there a way to fix this?
 
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doublespaces

Administrator
Oct 18, 2016
7,763
AZ
Thanks for the suggestions. I wanted the larger DCT cooler due to inspiration from the MS division. The M4 GT4 uses exactly the same coolers as a stock M4 except for one - the upgraded DCT cooler, which was taken from an M6. I guess the delayed heating of the DCT oil only really shows on track.

Now what you didn't know is that I already had an additional radiator custom made during December. It finally went in yesterday just in time for my response to your post haha. Turns out having a radiator made to spec costs next to nothing in China.

I also upgraded engine oil cooling and brake cooling just because why not. Let me go though each of the upgrades below:

New additional coolant radiator
*) Almost same total cooling area as the stock radiator. One pass radiator without DCT heater core. Connected in parallel to the CSF unit.
*) Keeps the DCT heating function intact because the CSF AT radiator is untouched. DCT track cooling is still handled by the separate oil cooler and pump.
*) Additional radiator sits in front of the condenser unit, and behind the DCT cooler with large air gaps on all sides, allowing fresh air to pass around it. Time will tell if this location works, or if the unit has to be placed somewhere else for the AC to work on hot summer days.
*) R+ racing coolant replaced with OEM coolant for increased longevity and lower cost.

View attachment 21415

Additional pictures:

View attachment 21409 View attachment 21413 View attachment 21406

Upgraded stock location oil cooler
*) Around twice the area of the stock unit. Around twice the depth as well.
*) Stock unit completely removed. New unit Installed directly to stock thermostat housing using adapter.
*) Semi-dry oil sump and associated oil cooler untouched.
*) Considering to replace the 95C thermostat with the OEM version to keep oil temps above 100C/210F on high ways.

View attachment 21405

View attachment 21407

Air scoops for brake cooling ducts
*) Intake raised to FMIC height to decease risk of scraping and increase longevity.
*) Air scoops added to increase intake area (the scoops were taken from a W212 Mercedes air intake)

View attachment 21408

End result

View attachment 21412

With the OEM bumper in place, everything still looks completely stock. Now all I need is some hot weather so I can start logging.

BTW @doublespaces since the site upgrade, the tables I made in post number 1 don't work anymore. Is there a way to fix this?
Nice work!

Regarding the tables, it was known they would break before the update. Instead of installing third party software I am waiting for a first party solution coming soon. Don't edit the tables as they will begin working on their own in the coming months. I may need to do a text replace so it's important the bb code formatting doesn't get changed. If that time frame is unsuitable I can attempt to recover it back to a test site and hand the data back to you in a readable format so you can repost it in a different way. But I am guessing it will be resolved in a month or two.
 

Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Nice work!

Regarding the tables, it was known they would break before the update. Instead of installing third party software I am waiting for a first party solution coming soon. Don't edit the tables as they will begin working on their own in the coming months. I may need to do a text replace so it's important the bb code formatting doesn't get changed. If that time frame is unsuitable I can attempt to recover it back to a test site and hand the data back to you in a readable format so you can repost it in a different way. But I am guessing it will be resolved in a month or two.
Absolutely no problem!

Another short update on the build:

Modified driver's side muffler

I find that the Z4 35i sounds much better from the passenger seat when a friend drives it top down. Ever since I experienced this for the first time, I wanted that sound on the drivers side. Now, since the muffler is much smaller on the passenger side, and even has an exhaust valve, I figured these must be the reasons for the difference in sound. I also assume the 35is has a different drivers' side muffler with less sound dampening to amend some of this.

Now how would one solve this problem then? One option would be to get a used 35is muffler. Another option would be to get a set of aftermarket mufflers, but who knows how they sound? A third option would be to cut open the drivers side muffler and simply modify it inside. However based on my experience driving with the golf-tea mod for just one day, I definitely still want the exhaust to be able to quiet down on highways.

The best solution then? Probably just getting another used passenger side muffler, and see if it can be installed on the drivers side, running an extra vacuum line.

And so I did:

3.jpg



4.jpg



2.jpg



1.jpg


Now the only problem with this setup is that the muffler had to be turned up-side down. Hence there is a risk the exhaust valve actuator hits something some day. But otherwise I am very happy with the result. Car sounds noticeably meatier when the valves are open. Now I just need to wait for the rain to stop, so I can get the top down and enjoy it.
 
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Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Quick update on various topics

Power

So after fixing all problems related to vacuum (engine+exhaust) and boost leaks it seems power has settled somewhere around 370-385whp / 435-445bhp according to virtual dyno, and a 100-200kph time of 9.4 which slots in between M4 (9.5s 425bhp) and M4 competition (9.3s, 444bhp). This is with catted down-pipes and stock intake (snorkel removed). Thanks to @RSL for helping with spotting my vacuum leak problem, and providing data on stock intake etc here.


drag.jpg


370-380whp.jpg


I am currently waiting for my tuner to review and optimize for driveability.


Cooling

Despite installing an additional radiator I still see coolant peaks upwards of 110C / 230F depending on ambient (up to 28C)


More discussions here

I have decided to order a new additional radiator which is around 40-50% larger, but mainly in thickness (52mm instead of 40mm)

Here's my childish drawing sent to supplier if anyone feels like copying. It is now set up to work in series instead of parallel. I expect to install the cooler in around one months time.

new-cooler.png


The total radiator area and volume will still be below that of an S55 so I do not expect this to completely solve my high coolant temps. To do any better than this, one would have to convert to a different style FMIC.
 
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bantam

Corporal
Nov 20, 2017
100
Out of curiosity, what ratio of water to coolant are you running? You may be able to improve your thermal performance by using less "coolant" and more water.
 

Asbjorn

Sergeant
Mar 10, 2018
432
Europe, based in China
Out of curiosity, what ratio of water to coolant are you running? You may be able to improve your thermal performance by using less "coolant" and more water.
When I was running the stock setup (csf radiator) I tried everything. Water wetter + 20% coolant (almost no color). Expensive Racing R+ coolant. Stock 50%. No difference. The main problem is power to radiator and the WOT% vs average speed that that car sees during hotlapping on track.

Here's the coolant volume used in different engines, an indication of the radiator sizes used.
N54 AT: 8.4L
S55 AT: 13.9L
S54: 10L
B58: 10.5L

Mines at 11L now and S55-ish power. I actually run 100% bmw coolant now (no water added) and my coolant temps have never been better. Not because of the coolant, but because of the bigger radiator. Temps are just still way too high for comfort on track.

I use 100% coolant because it has a higher boiling point, and then I can just top up with regular water when needed.
 
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