Funny enough, this popped up just as I've been thinking about getting another Z4M, but for use as a dedicated track car.
I had a beautiful Alpine White over Imola Red '06 6MT that I owned from 22k to 69k, and I miss the car more so than justaabout anything else I've sold.
Regarding problems:
The S54 is one of the absolute best engines from the past few decades, and One of the EXTREMELY small number of motors that surpass the 100bhp/liter mark. It is an incredibly involving motor, and with the sky high redline, linear hp curve and a surprisingly flat torque curve, it is just a blast. Toss it in a car like the Z4M, and you have a nearly perfect match between the motor and chassis.
Being that it is a detuned race engine for all intents, it does have a few areas that are moreprone to issues than others.
- Rod Bearings are the most commoly known issue, but they were replaced and upgraded by BMW after the '01 M3 engine issues. If you are not going to modify the engine, and if it's going to spendmost of its life on the road, then you will have little to worry about.
The best thing to do, if you want to ensure reliability even for track use only, is to preemptively upgrade them. VAC & Bimmerworld sell coated bearings, the latter being the best "out of the box" option without a doubt. However, the best way to go is WPC treatment, whichI rrecommendllooking up. It is used in all my engine builds, and I have never oncehad a treated part fail.
- VANOS problems are n't limited to the S54, as Overk1ll can surely tell youas wwell. However, it is a one-time fix. A company called Beisan Systems makes the VANOS components, but after an immense amount of research, engineering, and testin, has ffound exactly why the stock system fails, and corrected every known issue.
I have Beisan seals (and the other parts, as applicable) in every car in my signaturethat has VANOS, and have put them in over 2 dozen others (formerly owned vehicles, and friends cars). I have never had a single issue since.
- Oil Pump Nut vibrates loose due to harmonics. If you don't have pulleys and a lightweight flywheel, you simply should inspect it once in a while. However, something like VAC solution for the issue is a permanent upgrade and fix, and if you cangget one of the ATI Harmonic Dampeners fortthe car, it's worth doing.
Everything else, as with all BMW's, comes down to being willing to adhere to a strict maintenance schedule, and having a mindset of "preventative maintenance!".
I always, always recommend that when you do replace a maintenance part, do so with a known premium quality aftermarket bit. The cost is usually the same or less, but you are getting something that is not going to need to be replaced again, and likely offers a number of other advantages. For example, when youdo the ccooling system, instead of stock parts, go wit: CR radia tor from BW, Stewart pump, Samco Sport hoses, Aluminum T-stat housing, either an underdrive pulley kit (RE/TMS) or the ECS Alu WP pulley, etc. Youspe nd a similar amount but eliminate the cooling system as a worry system.
Following that method has been one of therreasons why I am able to modify my cars so extensively without having to live in them lol. It's saved me tens of thousands, and countless more money from the reduced replacement parts as maintenance.
If you like power to go with your perfectly balanced chassis and telepathic handling, the S54 is actually incredibly responsive to "relatively minor" mods when it comes to extracting more power.
My old Z4M wasn't as heavily modified as my E46 M3 (no internal/head work), but it did have:
- Supersprint V1 Stepped Headers (the ultimate)
- El Diablo Titanium exhaust
- VAC Carbon Fiber CSL Induction Setup
- TMS Pulleys
- ATI Dampener
- 11lb flywheel w Clutchmasters Stg3 clutch
- External oil cooler
- Beisan VANOS overhaul
- Stewart pump + Fluidyne rad + Samco hoses + Alu expansion tank
- Catch can
- VAC oil pump upgrade
- 3.91:1 OS Giken 28-clutch limited slip differential w Finned Cover
- AKG 75D Motor/Transmission/Differential mounts
- StopTech Trophy BBK w 6-piston 365mm 2pc slotted front setup and 4-piston 348mm 2pc slotted rear setup, bare aluminumfinish calipers, and SS Lines
- JRZ remote-reservoir 3-way coil overs w custom spring rates
- Hotchkis adjustable sways
- F/R solid 3-point/5-point strut tower braces
- Adj Rear Camber Arms + Extended/Offset front control arms (more caster)
- ALL bushings upgraded to AKG/RE/TMS High-durometer delrin or semi-solid, w TMS RTAB limiters, and reinforced diff carrier
- Kinesis 3pc forged 19x9.5" and 19x10.5" Street wheels (gunmetal face, polished lip)
- Apex ARC-8 ultra light 18x10" and 18x10.5" track wheels (17-18lb; flat black)
- OZ Racing Series featherweight wheels in 18x9 and 18x10 for track use (15.2lb front, 15.9lb rear) that I sold to get the Volks (matte gunmetal)
- Volk TE37SL 19x10 and 19x11 for max tire although I did have to roll the fenders to get 100 percent clearance running 255/35 and 285/30 Pilot Super Sports without having to run more Camber than is ideal (semi-matte white with dark silver writing, the latter to match the ST calipers)
I think that's the majority of the engine and drivetrain work, and the engine was dyno tuned for completely "bespoke" tune maps (93oct, 100oct, and a valet tune).
Here's some dyno numbers...
STOCK Engine, Suspension as listed: 274rwhp and 221rwtq
Same but w Beisan VANOS, AKG mounts: 279rwhp and 226rwtq
ALL the performance parts w CONFORTI "canned" tune: 329rwhp and 244rwtq
ALL parts with Custom dyno tune: 354rwhp and 266rwtq
ALL of above plus race wheels & ST BBK (-61lb unsprung rotating weight): 357rwhp and 267rwtq (the dyno recorded a 22.8 percent lower time to go to redline, in a "simulated drag race" run)
The gains in torque under the curve are insane, as much as 49lb-ft, and the curve itself is so flat compared to stock that you wouldn't think that the dyno's were from the same car.
Coupled with weight removal, such as Pole Position seats (CF/Kevlar), dry carbon fiber body panels (hood, trunk, rear diffuser, side skirts, mirrors, front bumper, front splitter, front fenders) and some internal bits (center console, trim), Ultra Light Lithium battery (5.5lbs), removal of spare/trunk carpeting+insulation/toolkit/etc, and other bits and pieces, I removed a total of 221lbs of sprung weight and, while it was expensive to do so, maintained an exact 50:50 f-r weight distribution, and side to side with a half tank and me in the drivers seat is 50-50 as well.
Weighing every replaced suspension component and their replacements, as well as the power adders, showed that I lost another 18lbs from the engine parts, but much more importantly, 39lbs from the Clutch/FW, 32.8lbs from the suspension components, 14lbs from the brakes (keep in mind that the calipers went from tiny little sliding to massive 6/4 piston monoblock fixed, the discs/rotors from 33x to 365/348 and around 45pct/50pct thicker w 2.5x as many vanes, and the pads are not only massively larger they're also a LOT thicker), 29lbs from the Volk TE37SL/58lb from the Apex ARC-8, and 7lb from the 19" PSS/13lb from the 18" PS Cups (vs stock).
The amount of unsprung (suspension components, brakes, wheels, tires) lost transformed the car from immensely capable sport car to "An Exige S 240? Meh, too uninvolving" lol. Every single one of the cars limits was dramatically increased.
The weight lost from rotating/driven components, it profoundly increased the "rev-happy" nature of the engine, and combined with the billion percent improvement from the AKG mounts (almost no NVH increase, BTW), and I actually had to relearn to drive the car because of how much "lighter" the engine felt. I even ordered and installed the UUC EVO3 SSK and DSSR, with a ZHP 6MT shift knob, because the factory shifter became the bottleneck for fast shifts.
Also, they reduce the amount of parasitic losses in the engine and drivetrain, meaning that you are able to actually use more of the power that'saalready there.
Dropping 400lbs withoutsstripping the car is not easy or cheap, but as most wasn't done until after the power mods, and the unsprung weight from the wheels is as simple as swapping the stock back on (dramatically reducing theeeffects), I have some numbers that I acquired from two different "events" at a repurchased and repurposed airstrip (full length, and repaved to track smooth). For a comparison, my friend's 997 Turbo w an insane amount of money in it, including 2-sizes-up bigger turbos, 4.0L engine bore&stroke, 480 percent larger total IC space, 4.5" completely insulated inlet
