E89 Z4 Track-ready Sleeper Build

[Asbjorn]

@Asbjorn Regarding oil starvation, did the pump not help at all or is it that helped but not eliminate pressure drops completely?

It did not help at all. I believe its because the electric pump I used, which was intended for oil cooling, does not move near enough volume to keep up. The S55 uses a mechanical pump to do the same, and I assume it is much more powerful.

I stopped doing track days a few years back and got into karting instead. It is equally expensive overall, but doesn't hurt as much when you blow up an engine/miss a braking point.

 

[marv85]

@Asbjorn karting is a lot of fun! It seems I joined this party late but I do appreciate all your documentation, I’ve enjoyed going through it in the past few months.

Did you blow an engine ?

 

[Asbjorn]

@Asbjorn karting is a lot of fun! It seems I joined this party late but I do appreciate all your documentation, I’ve enjoyed going through it in the past few months.

Did you blow an engine ?

The N54 in the Z4 is still alive after almost 200k km. But yeah, seized a couple for iame x30 karting engines last year lol.

PS I noticed in the other thread that you said oil starvation is not an issue based on your logs. How do you see that from your logs? You also mentioned upgrading brakes, hopefully by that you just mean changing (not upgrading) the pads to track-type pads, and didn't waste money on larger calipers and rotors.

 

[marv85]

@Asbjorn I'm glad to hear the N54 is still alive! This is my 4th N54. I just got back to the platform for purely sentimental reason, but then decided to start tracking the car

regarding oil starvation, I quickly parsed one of my logs and I didn't see any dips that looked worrying at high RPMs. That's where my statement comes from. I say it wasn't an issue, at this point, because I didn't push the car. Once I get new tires/brakes, I'm sure I'll start seeing signs of starvation similar to everyone else that tracks the car. This is why I'm hoping to get ahead of it somehow. The current leading path is an accusump. I also saw the VAC dry sump pan for N54 but the price is outrageous...

Here's a short log from the track if you'd like to take a look. I removed a lot of the channels on this one for cleanliness.

datazap.me | marv85 | short log

datazap.me

Regarding brakes. I have not yet upgraded my brakes. I just did RBF600 for my last track day... For future track days, I was looking for some BBK from stop tech. But I would love to get your 2 cents on this matter. Do you believe stock E92 rotors with just track pads (say Blue stuff) and track fluid (say RBF 660) is enough ? my goal is not worry about the brakes being there for me lap after lap, corner after corner. Whatever achieves that is fine for me. The car won't do more than 2 to 3 hot laps before needing a cooldown laps so I need the brakes to perform 2 to 3 hot laps at a time.

 

[Asbjorn]

@Asbjorn Once I get new tires/brakes, I'm sure I'll start seeing signs of starvation similar to everyone else that tracks the car. This is why I'm hoping to get ahead of it somehow. The current leading path is an accusump. I also saw the VAC dry sump pan for N54 but the price is outrageous...

Here's a short log from the track if you'd like to take a look. I removed a lot of the channels on this one for cleanliness.

datazap.me | marv85 | short log

datazap.me

That nxm kit is super cool! And no, it does not seem like you are experiencing oil starvation as of yet. There is no speed or g-force trace in the log, so I can't tell how hard you are braking. Normally you should experience oil starvation even on street tires as long as you brake hard and long enough, ie from high speeds (say from above 120mph to below 60mph).

That VAC dry sump kit looks awesome. I did not know it existed. Has anyone done logs yet? If not, fya @AzNdevil haha

As for a bbk, please dont do a stoptech kit unless forced to. Just go race pads and race brake fluid and be done with it. RBF should be is fine, it is more about how new it is. As for pads, just remember to swap both front and rear pads at the same time. This as to not alter the brake bias unintentionally. EBC blue/orange stuff is a bit too "street" oriented in my opinion, but OK. Those pads wear out fast and are relatively gentle on the rotors. You can get harder pads (with higher friction coefficient) that bed in faster and last longer (at the expense of the rotors). I prefer the latter because track time is often limited. Then ideally you swap back to street pads after the track day.

 

[marv85]

@Asbjorn I was hitting myself on the head for not adding speed to the logs… but I can confirm that I wasn’t braking hard. To put things into perspective, the fastest lap I did at Laguna was 1:57 after which the brake pedal would sink three quarters of the way before I feel any braking. So I decided to stop. Not to mention all the juddering I would feel.
What’s your favorite racing pads ?


Also, why avoid stop tech ? Is it just a waste of money or are there any other reasons ? I’m just curious, obviously, I prefer to replace the least amount of components that helps me achieve my goals.

 

[Asbjorn]

@Asbjorn I was hitting myself on the head for not adding speed to the logs… but I can confirm that I wasn’t braking hard. To put things into perspective, the fastest lap I did at Laguna was 1:57 after which the brake pedal would sink three quarters of the way before I feel any braking. So I decided to stop. Not to mention all the juddering I would feel.
What’s your favorite racing pads ?


Also, why avoid stop tech ? Is it just a waste of money or are there any other reasons ? I’m just curious, obviously, I prefer to replace the least amount of components that helps me achieve my goals.

I have been pretty happy with Hawk dtc. They are a bit on the aggressive side (on/off-ish) and hard to modulate during trail braking. But at least you get a very confidence inspiring pad.
Soft pedal = brake fluid problem
Hard pedal no brakes = brake pad problem
Juddering = bed in problem if I remember correctly (dont quote me on this)

I did not mean to advice against stop tech as a brand, but against BBKs in general. As an example, if you do a BBK with street or "sport" pads, your brakes will equally overheat on track, and you gained nothing. At best, what you really get with BBKs is better looks (something I personally opted out of by going all in with custom OEM+ colors so noone could even tell I upgraded). At worst, you will think you can brake later and then end up in an accident because you couldnt.
BKKs that are poorly dimensioned, may also give you a longer brake pedal travel and a different brake bias. In any case, you will almost always end up with a slightly longer braking distance on the street after installing a BKK, no matter how well it is designed.

Yes they can reduce unsprung weight, yes they can be designed properly, yes they make it easier to swap pads, yes they may delay leakage from happening, yes you can get endurance calipers to fit thicker pads, yes they may look good, bla bla bla but at what cost? What you actually need, BKK or not, is race pads and fluid and to change them often. Don't do what I did unless you know exactly how and why you are wasting your money.

The N54 overheating (coolant, not engine oil) will be the bottleneck over the brakes if you run the right pads and fluid with OEM hardware.

 

[AzNdevil]

That nxm kit is super cool! And no, it does not seem like you are experiencing oil starvation as of yet. There is no speed or g-force trace in the log, so I can't tell how hard you are braking. Normally you should experience oil starvation even on street tires as long as you brake hard and long enough, ie from high speeds (say from above 120mph to below 60mph).

That VAC dry sump kit looks awesome. I did not know it existed. Has anyone done logs yet? If not, fya @AzNdevil haha

As for a bbk, please dont do a stoptech kit unless forced to. Just go race pads and race brake fluid and be done with it. RBF should be is fine, it is more about how new it is. As for pads, just remember to swap both front and rear pads at the same time. This as to not alter the brake bias unintentionally. EBC blue/orange stuff is a bit too "street" oriented in my opinion, but OK. Those pads wear out fast and are relatively gentle on the rotors. You can get harder pads (with higher friction coefficient) that bed in faster and last longer (at the expense of the rotors). I prefer the latter because track time is often limited. Then ideally you swap back to street pads after the track day.

well i finally built a canbus module to have coolant temp, oil temp, accel pedal %, brake pressure, steering angle, speed integrated to racechrono but i havent added oil pressure yet since i rolled my own solution instead of the nxm kit

i will add this in before my next track session, afterall i finally hooked up my oil pressure sensor just because i want to see how bad it gets

fwiw i didnt notice anything out of the ordinary when i glanced at my gauge last session but i was also learning the course so it doesnt count

Also, why avoid stop tech ? Is it just a waste of money or are there any other reasons ? I’m just curious, obviously, I prefer to replace the least amount of components that helps me achieve my goals.

imo stoptech is mehh at best, its not bad but there are better options to be had depending on your connections
ap radical 5000r 9660 has the same piston area as the stock 135/335 caliper but you will need custom adapters + rotors to run them.

lots of different race pads are available for these entry level grassroots calipers as well but they dont have dust shields so expect to rebuild them every year or two when they start to drag

either way, you will need to upgrade to stainless steel brake lines both front and rear and track pads at a minimum
personally im not a fan of hawk dtc pads see if you can get a hold of pfc11 or pfc01 pads for both front and rear

what exactly are your goals? i just started to drive my car on the track and trying to make a n54 survive is starting to become a nightmare

 

[marv85]

@Asbjorn I had issues with both (1) and (3). I believe RBF 600 wasn't up for the job, at least with my stock setup. and (3) either a bedding problem or my rotors are just bad at this point.

Soft pedal = brake fluid problem
Hard pedal no brakes = brake pad problem
Juddering = bed in problem if I remember correctly

@AzNdevil my goals are not crazy for now. I just want a "reliable" car to enjoy on track. Last time I went out, the bottleneck was my brakes. I want to remove that bottleneck. I want to have consistent braking power corner after corner, I want to trust the brakes will be there for me, basically.

Given the feedback from you and Asbjorn, as well as my research, I'm leaning towards new OEM brake rotors and track pads/fluid.

I see you are running Zimmerman. should I go cross drilled or Z coated ?

 

[Asbjorn]

@Asbjorn I had issues with both (1) and (3). I believe RBF 600 wasn't up for the job, at least with my stock setup. and (3) either a bedding problem or my rotors are just bad at this point.

Soft pedal = brake fluid problem
Hard pedal no brakes = brake pad problem
Juddering = bed in problem if I remember correctly

@AzNdevil my goals are not crazy for now. I just want a "reliable" car to enjoy on track. Last time I went out, the bottleneck was my brakes. I want to remove that bottleneck. I want to have consistent braking power corner after corner, I want to trust the brakes will be there for me, basically.

Given the feedback from you and Asbjorn, as well as my research, I'm leaning towards new OEM brake rotors and track pads/fluid.

I see you are running Zimmerman. should I go cross drilled or Z coated ?

Hmm RBF 600 should have been OK if new and properly bled. I used Endless, but any brake fluid gets worse with time/use.

https://parsbrorc.com/?page_id=33

Your rotors most likely started to judder due to bad bed in/uneven surface material caused by the pads. You can most likely remove the juddering with proper bed in and pads. With EBC orange I had juddering that started at mid-temps and then disappeared at high temps. With Hawk I don't think I ever had juddering, and they always worked even with bad bed in (unlike the orange stuff). Anyway, I believe EBCs documentation has a chapter about this phenomenon. Another thing to avoid is holding the brakes while parked just after a track session where they pads+rotors are super hot.

For track use I would always avoid cross drilled rotors to lower the chance of cracks. Cross drilled looks great on the street though.

 

[marv85]

@Asbjorn I agree, I was surprised that RBF600 wasn't enough. It was brand new, I had a shop do it for me two days prior to the track day. My hypothesis was that my brakes were dumping too much heat back into it. I mean it's either that or something else is wrong with my brakes. I read old posts on e90post where folks had intermittent brake problems and it was traced back to the vacuum pump. Hopefully, I'm overthinking and it's just a matter of swapping the fluid.

I'll stick to Z coated Zimmerman rotors.

 

[AzNdevil]

@Asbjorn I agree, I was surprised that RBF600 wasn't enough. It was brand new, I had a shop do it for me two days prior to the track day. My hypothesis was that my brakes were dumping too much heat back into it. I mean it's either that or something else is wrong with my brakes. I read old posts on e90post where folks had intermittent brake problems and it was traced back to the vacuum pump. Hopefully, I'm overthinking and it's just a matter of swapping the fluid.

I'll stick to Z coated Zimmerman rotors.

on top of what @Asbjorn said, check if you have chunks of rubber still stuck to your tire, they will cause everything to vibrate as well, cut the chunks off with side cutters and dont try to rip them off with your fingers...i learned the hard way and somehow cut my thumb open in the process after my last practice session

zimmerman rotors are good, ive always used them when i can
go for fresh fluid, new rotors and a higher temp brake pad first

pad choice is a subjective thing but, if you need to drive in the cold on street tires with the same pad, you cant go too agressive cause you will either have no cold bite/brakes or they just lock up your tires once the pads are warmed up

 

[marv85]

Thank you for all the advice. You guys saved me a lot of money