Supercharged z4

Supercharged z4 DEFAULT


Highway, 3rd gear (prior to the retune... the car no longer puffs smoke):

On the dyno, where the car made 285 whp with the old (rich) tune and stock flywheel/clutch:

Supersprint Race Exhaust:

Supersprint headers added:

Update 9/10/2013: Rev, Parking Speed, Launch (stock headers/gearing)

Update 9/14/2013: Driver's perspective (stock headers/gearing)

Pros: Intoxicating sound. Where a new Altima poses a serious challenge to a stock Z4 in a stoplight battle, this kit will give your base car the power to leave anything on the road short of dedicated sports and muscle cars. It bestows the grunt to go with the Z4’s looks.

Cons: Installation nightmare for first timers. Little tech support. Several issues that I still need worked out.(Edit 10/3/2014: All issues sorted).

Grade: C- (Edit 6/8/2014: kinks worked out, B)

This is a great mod if you realize what it doesn’t do to a Z4 – turn it into a Z4M. The two are totally different cars with separate purposes. I suppose they look the same; are similarly quick in a straight line; and they share some parts and a badge. But that’s where the similarities end.

Consider the following facts:

1. A modified car will never be as smooth or run with as few quirks as a car that’s totally OEM, especially when it comes to a BMW.

2. Mods always look better in the book than on the car.

3. Allotting the funds to purchase a mod is only a third of the experience. You still need to deal with installation itself, including unexpected expenses relating to the install. The car may be down for long periods. It’s common practice to multiply the expected downtime by three to five in order to get a realistic estimate.

4. The Z4 is a low production car which shares many parts with the E46 3 series. Major modifications are often adapted from the vendor’s E46 catalog. Don’t be surprised if your application doesn’t garner the same attention from tech support. Businesses exist to make money. They devote time where they will net the greatest return.

To decide if this mod is worth further investigation – and this review worth reading – ask yourself the following questions:

1. Do you love your standard Z4 as-is, but long for more power?

2. Is your car in good condition? Are you sure the miles have accumulated abuse-free, and do you know what maintenance has been performed?

3. Do you have access to a shop that has successfully completed a supercharger install on an E46 or E85 before? Whether you plan to do the install yourself or through someone else, it’s always important to have an expert available that has done an install before. If not, you will be billed for the shop’s education. You’ll spend a lot of time beating yourself up, staring at the depreciating eye candy immobilized in your driveway.

4. Is the Z4 a second car? Never modify your daily driver.

5. Do you plan to sell your car in the next five years? Don’t spend the money if you expect to sell.

6. Do you ever want to track the car more than a couple days a year? I would not drive an M54B30-equipped car on the track due to the oil pump nut issue prevalent on the E46 forums. The E85 is too low volume to have had the problem raise its head on here. A Google search will net all kinds of info.

I say the above to set reasonable expectations for this modification and ensure an honest review. That said, forced induction is the only power mod that will put the car in a different league. You gotta pay to play.


One thing that annoys me about the stock Z4 is that it looks faster than it really is, and every Road and Track reader with a 260+ horsepower family car or turbo diesel truck tries to rub it in. I enjoyed my car when it was stock, and the obnoxious attempts to get me to engage in a contest of acceleration never kept me up at night. But, there was always that secret, nagging desire to have the power to immediately put challengers in their place. I don’t condone street racing, but let’s be honest – it’s satisfying to live up to the “sleeper” name when it poses no danger to the public… or hop in front of that slow-mover in the left lane that’s rapidly trying to close the gap when they see you move to pass. We all have an inner child.

Still, that’s not why I pursued this mod.

The real reasons I did it were as an exploration in engineering and a challenge to myself. I discovered how overbuilt the M54B30 is, and it has so much potential it isn’t utilizing. I wanted to exploit it.

I wasn’t planning on going FI until the VF kits came out, on sale for 25% off. My non-M had been sitting more than it should have been, because I drove the M every time I had the choice. Actually, the only time I drove the non-M was when I felt guilty because I’d been putting so many miles on the M. A sports car that just sits is useless, so I justified buying the kit because it would give the car similar performance to the M but with a totally different feel. I’m about 95% satisfied with the final result. The road to get there was long and difficult.


After buying the kit, there were delays in it shipping. This is common, and not just for VF. Every time I’ve ordered a major modification for the car there has been a delay, whether it’s through G-Power, Supersprint, or VF. I had the kit shipped to my parents’ house (450 miles away, bad idea) because I could muster more help from interested parties there, and I had more access to tools and workspace. The installation instructions said 8 hours start to finish, so with several of us working, I figured it would take a weekend or two. It ended up taking five.

The biggest issue I’ve had with the whole experience has been the installation instructions. The instructions included with the kit were for a Z3 with the Vortech V2 blower. The Z4 is different in that there’s no power steering lines to modify, and the V3 unit has a self-contained oiling system. For someone who has never installed a VF kit before (or any other for that matter), trying to figure out which steps to omit was a pain. There was a lot of backtracking, reading ahead, and “making sure I’m sure” before proceeding. Why, after paying thousands of dollars for a kit, was I having to waste brainpower and interpret my next step from instructions that weren’t even for the right car or supercharger? I know VF had at least one Z4 that came to them for test fitting… why not take some pictures during the install process and spend a few hours on some new instructions?

The instructions came on a CD, and while it’s nice to have an electronic copy, a hard copy should have been included too. Otherwise you’ll either have to print your own or drag computer cables out to the garage.

Many of the hoses weren’t the correct length, which required trimming on the customer’s part. I modified several of the included hoses, and others required the customer to cut half of an old hose and attach the other half of a new one to it. One came into contact with the serpentine belt when fitted, so I bought a new one from the auto parts store. While not a huge deal, it’s the attention to detail that shines through. A quality kit would have included new hoses of the correct length, which I guess would cost more. You get what you pay for - there were a lot of things that were left to the customer that shouldn’t have been.

Another example is the MAF sensor extension - I had to cut off the MAF sensor and extend the wiring. A better way to do it would be a plug and play solution, rather than having the customer cut the OEM wiring and solder/heat shrink wires. I can solder, but I really wasn’t comfortable cutting off my old MAF sensor when a simple connector would have done the trick.


I ran into some other issues that were due to my own inexperience. When I first fired up the car, it idled erratically. After troubleshooting and a few emails to VF, I figured out that the MAF sensor’s orientation wasn’t correct. Which brings up another point – tech support was very slow to get back to me, and they answered about every third email I sent their way. So, if you run into an issue, expect a week or two delay in getting a response. I relied heavily on the forums.

Anyway, I ended up isolating it as the MAF sensor by unplugging the MAF. This put the car in speed density mode, which will get you home, but isn’t meant for long-term driving. In fact, it takes several tries to start the car, and you have to let it idle for at least 15 minutes before driving it. Otherwise it will stall. I oriented the MAF correctly, and the issue disappeared.

Once the MAF issue was sorted, the car ALMOST made it out of the driveway before the radiator drain plug fired out from the bottom of the car. Again, this was my own doing – I had stripped it when I removed it. Because the dealership is closed on the weekends, I had to order a new one to be shipped in… and wait another weekend and 900 mile round trip…

After replacing the drain plug, the car began to overheat. I always shut the car down as soon as I saw the temperature rise, and never had any warning lights illuminate. Based on VF’s recommendation, I decided to replace the thermostat since it was at about the mileage where they fail. This was a misdiagnosis, but I don’t regret replacing it. A thermostat should fail in the open position, and the car will just take longer to warm up. My symptoms were from air in the lines. I had read that the system is self-venting. Maybe it is, but you should ALWAYS vent air from the lines any time you mess with the cooling system.

After purging all air from the lines, I drove the car around a bit and noticed a leak when I checked fluid levels again. The leak was due to the included radiator hose being too long, which I cut too short. I made the mistake of driving with the radiator cowl off the car as I was sorting through all the issues. The lateral movement of the radiator stretched the hose and caused the leaks. A new hose from Autozone and buttoning down of the radiator cowl solved this issue.

I finally gained enough confidence in the car to drive it home. On the last 100 miles of the trip, the throttle response didn't feel right. In the last 20 miles, I knew something was definitely wrong. I coasted home at low rpm and popped the hood. One of the hoses connected to the intake manifold had completely detached, causing a major boost leak. When I originally installed the band clamps, I tightened them down to what I thought was “about right” since it’s very possible to break things by over-torqueing them. As almost anyone who has installed a FI kit before will tell you, too tight is just right. After tightening down everything, the car drove great.

In the next few weeks I put about 1000 miles on the kit, including a spirited run with our local CCA chapter. The spirited run was the culmination; I progressively built up to it, pushing the car more and more until I was confident it wouldn’t blow up spectacularly. If you install a new kit, every time you drive the car your senses are on full alert. Any sight, smell, sound, or feeling that just isn’t right will cause you to pull over and check everything.

All was going great, and I left for two weeks on leave prior to flying out for Afghanistan. When I returned, the car idled erratically. I unplugged the MAF, and sure enough the idle smoothed out. I swapped in a buddy’s MAF sensor from his 330ci, and isolated the issue to a failed MAF.

The moral here is, expect to spend some time troubleshooting and lose a few years off your life worrying about your car. There were days that I looked depressingly on a car that ran perfectly fine before I started screwing with it, and the only way it was going to run again was if I sorted out the god**** mess I created. Realize that the initial price of entry doesn’t include a lot of things you’ll need or want – gauges, a pod, supercharger maintenance items, general wear items, things broken during the install process, and so on.

The car still has a few issues, including some mild oscillations that surface on very rare occasions (once or twice a week) at part throttle, and a check engine light from it running rich. The CEL takes a couple hundred miles to surface after a reset. I haven’t hooked up my AFR gauge because I’ve run into issues with installing the pod, and I want to do it simultaneously with my Supersprint header install since they already have additional O2 sensor bungs built in. Despite checking and double checking everything, I haven’t found a mechanical issue that would cause the car to run rich. My next step is to take it to a quality shop to see what they say, because I’ve had a few places around here look it over, unable to provide any suggestions.(Edit 6/8/2014: VF has sent me a new tune, which I will test out over the next few weeks. Most of my issues have been sorted, so hopefully this tune will be the final piece! The car put down 285 rwhp with the previous tune and Supersprint headers. I'm expecting a few more horsepower since AFR will be optimized. VF has since updated the instructions and tune, as well as calling me to make sure everything was good to go. I will revise the kit's rating to a "B".)

Driving Impressions

The powerband is extremely peaky. The car feels stock up until 4000 rpm, and even then it’s only mildly quicker. After 5000 rpm, power ramps up and the car starts to push you back in the seat. 6k rpm to 7k rpm usually provokes language I won’t post here. I’ve seen enough dynos to know that a centrifugally supercharged car’s horsepower output is essentially a straight line up to redline. With this car, it feels more exponential. It’s like wow… woah… WOAH!! (Edit 10/3/2014: Now that the tune has been sorted out, the car feels exactly like the dyno shows... power builds progressively until redline).

The best part of the kit is the sound. A sports car simply isn’t a sports car without an exotic song. It’s not obnoxious but it turns heads, more so than my supercharged M. From the driver’s seat, the Vortech brings with it two new sounds. The first is the familiar belt-driven supercharger whine. It’s very faint, but you can hear it over the race exhaust. It's also very different from roots or twin screw whine! Its pitch increases with rpm, and it's highly desirable. The second new sound is the hiss of boost. It obviously builds with rpm, and at redline it overpowers the engine’s scream. At full throttle, the car sounds like a jet.

From outside the car, the whine is more noticeable. You can hear it echo off buildings at low speeds. Even non-enthusiasts know the car is modified. As previously stated, my goal was never to grab attention, but the overwhelming number of compliments from strangers is definitely a perk. With the M54 being such a quiet engine, the supercharger defines the car.


With the issues that I’m still sorting through, and the long road to get to this point, it’s hard for me to say whether I would do it again.(Edit 10/3/2014: I would absolutely do this mod again, though I would have it done at a shop). If I didn’t have the desire for the education motivating me, I would have had everything done at a shop I trust. When you add everything up, it would have been cheaper. Not to mention less painful. Living where I do, this isn’t a simple task.

I think an M has more midrange, and could probably beat a car with a VF kit off the line assuming equal drivers.(Edit 6/8/2014: A 3.0i with this kit CAN beat a stock Z4M in top end. With headers, it's no contest). But that doesn’t really mean anything except to people looking to brag. A car with this kit will always grab more positive attention if that's what you're after.

At this point I haven’t decided if I will upgrade the kit to a custom 11 psi “stage 2” with an intercooler and WMI; or sell the kit and go for an Active Autowerkes Stage 2, Technique Tuning Turbo, or ESS TS2.(Edit 6/8/2014: I plan to keep the car as-is, having paired it with headers, full exhaust, 3.64 final drive, and a lightweight flywheel/clutch combo... I may add WMI and cams later; it feels like it has over 400 bhp). For those that love their cars but long for more power, and have access to a good shop that can avoid or sort through issues, this kit is a great way to go.

Last edited by pokeybritches; 10-12-2014 at 04:35 PM..


Supercharged G-Power G4 3.0i EVO III BMW Z4

While BMW has opted for a twin-turbocharger system to boost extra power from its 3.0L straight six engine, German tuner G-Power has decided to adopt a new supercharger design for its latest performance upgrade for the Z4 roadster. G-Power is no stranger to drawing big power from BMW engines. The tuner holds the title for the world’s fastest street-legal BMW with its twin-turbo M5, and for its Z4 package its engineers managed to ring out 375hp (280kW) and 310lb-ft (420Nm) of torque from the 3.0L mill.

G-Power used an ASA T1-12 supercharger to reach the new power levels, and also needed to upgrade the engine’s ECU and exhaust system. The exhaust upgrades consists of a set of racing-headers and high-flow catalytic converters.

Other modifications include a mild sports bodykit, 20in light alloy wheels, a stiffer suspension set-up and uprated brakes with eight-piston fixed calipers and 380mm discs.

The end result is a 0-100km/h (62mph) time of 4.9 seconds and 0-200km/h (124mph) time of 15.1 seconds. This makes the G-Power Z4 3.0i comparable in performance to BMW’s own Z4M. Pricing for the kit starts at €18,850 ($29,900).

G-Power G4 3.0i EVO III BMW Z4

  1. Xfx rx 480
  2. Swoop ponytail
  3. Rectangular plastic baskets

akaik their isnt another z4m running the ess stage 2 + kit in the uk... or even the stage 1 for that matter.... i wish another uk buyer would come on this ride with me so ive got someone to build ideas with, ive gotten pretty friendly with afew american owners now that i actually talk to on skype weekly..... ESS have developed this kit over 10 years on the m3's their track record and knowledge is legendary in the bmw FI world....

Gwatson had a z4 3.0litre kit i think ........Edit.... gwatson had a 3.0l Ts ess kit....

i can gaurantee however if i wanted to strip this thing off i could sell the kit within an hour for solid money..... would i ever do that NO WAY>>>>

ok mark, fuel econ is terrible on boost, the car has the m5 v10 injectors :-(off boost i can match the stock cars mpg figures....

costs are very decieving i found..... by the time youve purchased your kit and installed it ect ect you looking to add a quite abit to the bill.... i think in installs alone ive spent 4k easily..... In stage 2+ form the pretty much the whole front end of the car was removed, it was a solid week of work.....

selling on??? i very nearly sold this car after recieving an offer i was stupid to refuse really.... i would never split it from the car and i understand it will take longer to sell but it WILL sell for sure.....

the vt1 kit will net you 440 hp, the stage 2 500hp then stage 2 + kits (methanol/water injection) around 540ish bhp.... this car with 540hp feels ludicrous... meth can be turned off with puts you back to around 500-510bhp.... 500 feels just as silly but more deal-able with.....

i service the car yearly.... But if im honest its the best money ive spent, the car is an absolute blast..... its turned a car i love into a car thats a true one off.... put that into a car that ive had from 2007 and spent all its life with me, its like new and still only 11k miles from its weekend use.... i wont sell it, sometimes i do get the urge but i wont....

interms of driving you wouldnt no its their if you just pootle around, it drives exactly the same as your car does, just faster, part throttle, on throttle, off throttle everything is stock like delivery.... i can spin the tyres in 1-3rd pretty easily.... if its warm i can hook at the top of 2nd.... the car sounds like induction raw with massive whooooooshhhhhhh.. lots of blow offs, pops and whistles from under the bonnet, lots of fire from the exhausts, lol its a real event.... i travel to my sprint track in convoy with afew of the members, the one member has a v8 r8 which is can dispense with very very easily..... its turned the z4m from sports car performance into a new league of performance. its been a costly road however. Would you like to come and see the car and ill spent a few hours with you and run you through the complete build..... its something i researched heavily for about a year then have carried on over of the past years.....

ess customer service has been faultless....

and simpson have made it a pleasure to be apart of.... put simply.... if i could have all my money back would i??? NOT on your nelly..... the best money ive spent in a long time.... do your figures and work it out properly, ive had some shocks along the way that i did not factor in in the initial build price.... ive also upgraded lots of engine components now, catch cans, meth, kevlar hosing, ss murray clamps, billet s/c wheels ect alot more.

also add in costs for better brakes ect ect and supporting mods to the car in general....
Supercharged Z4 Exhaust Comparison - OEM vs Supersprint

BMW Z4 Supercharger Kits

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Z4 supercharged

Drop Top Racer: Supercharged BMW Z4 M Roadster

Coming out of a fast right hand corner the 1996 328i went from gripping the road to sliding irretrievably out of control. The BMW fishtailed left and right and then sailed off the road. The passenger’s side of the sedan hit a tree squarely in the center after which the car flipped end over end down a steep slope for 130 more feet. A midnight canyon run in the mountains above Albuquerque, New Mexico with a group of fellow car enthusiasts had just come to an abrupt end.

Luckily the only scratch that owner Andrew Golden got from the accident was caused by the sudden and violent deployment of the air bag. The car on the other hand was a complete write-off. While an accident like that might make some people reconsider the car hobby, in this case it didn’t affect Golden’s appreciation for high performance cars and driving in a negative way. If anything, it only served to reinforce his appreciation for the machines from Bavaria, in this case how incredibly safe they are in a serious accident like the one he had just experienced. In retrospect the young enthusiast is realistic about the cause of the accident, which stems mainly from a bit of youthful enthusiasm paired with some dangerously worn tires. “The tires were bald, but I was like ‘I’ll buy swaybars first,’” laughs Golden when he thinks back about the accident. 

Golden got the BMW bug from his father, an affliction which is also shared with his three brothers. “My dad owned an 1800, so I have always been around them,” he says. “I remember an E30 convertible that he used to drive me and my brothers around in. Even when it was cold, he would drive with the top down.” The 328i that had been destroyed in such spectacular fashion was Golden’s first BMW. He was a high school student at the time and had built up the E36 sedan with an improved suspension and a supercharged motor. It didn’t take long for him to move on to another BMW after the accident. A couple of weeks later the now deceased 328i was replaced with a ’99 Z3M Roadster in Dakar Yellow, which was eventually replaced by a 2009 factory JCW (John Cooper Works) MINI. He kept the MINI for a year and a half before trading it for the black Z4 M Roadster pictured here.

“It was a trade in at my work and after staring at it for a month, I just had to trade in my MINI for it,” he says. The Z4 was painted in Black Sapphire metallic, a hue that perfectly suits the roadster’s flame-surfaced lines. The interior of the Z4M was as striking looking as the exterior, with two tone Light Sepang Bronze leather and black upholstery and wood trim. In fact it was the interior that ultimately sold Golden on the Z4: “It had every option except extended leather.”

The Z4M isn’t exactly a slouch in stock form, powered as it is by a 330-hp version of the S54 that powered the E46 M3. But given his history of making his cars faster, Golden couldn’t resist upgrading the potent two-seater. A shorter ZHP shift knob was the first part that was installed- “It was cheap,” says Golden- but that quickly snowballed into more radical modifications. The handling was sharpened up with adjustable H&R coilovers. “My goal was to increase the handling and looks for the track and street,” he says. “Coilovers were ideal for this as it allowed me to slam it for street driving and raise it back up for the track.” A better flowing stainless steel, cat-back exhaust from Stromung was installed as well. “The exhaust sound is perfect from the Stromung. It makes a nice deep tone with some popping and burbling on deceleration and no drone during daily driving.” At this point Golden also installed factory aero side skirts for a sleeker appearance.

“After my first autocross, I realized I needed to fix the understeer,” he says. “This lead to my wheel and tire upgrade. I picked up a set to APEX ARC-8 wheels from a forum member who had put only 100 miles on them. They were the exact fitment I was looking for.” The APEX wheels measure 18x9.5-inches at the front and 18x10-inches at the rear and are wrapped in sticky Hankook RS3s sized 255/35 and 275/35. “I also increased the front camber to -3 degrees while keeping the rear at -2.5; the result was amazing on the track and understeer was no longer a problem. The car's handling after the upgrades is night and day. The tires are so sticky and along with the stiffer suspension, it's a dream to drive. It's a great track car. The chassis is very stiff and balanced.”

Next up was adding some more power to the equation. While an intake and an ECU reflash would have sharpened up the S54, Golden researched a few companies that offered supercharger kits for the Z4’s S54 engine and settled on VF Engineering out of Anaheim, CA. The company’s VF570 Stage II kit was selected, which, you guessed it, is designed to increase the S54’s horsepower output to an impressive 570-horsepower at the crank. The conversion centers around a V3-SQ trim supercharger that delivers compressed air into a cast intake manifold with an air and water-cooled cartridge inside. Larger Bosch fuel injectors replace the stock injectors. The conversion also includes a software reflash, CNC machined alloy bracket for the supercharger, OEM idler pulleys, molded intake ducting and a K&N air filter, to name just a few from a long list of parts.

Golden installed the kit himself. “It took about three weeks, working in my spare time,” he says. “I think I worked on it for about 15 hours total.” Normally, the intercooler for the supercharger is mounted in front of the BMW’s oil cooler, which in turn is mounted in front of the radiator. Golden decided to install the intercooler between the oil cooler and the radiator, which required trimming off some of the radiator’s plastic shroud. A set of Active Autowerke headers were also bolted to the engine during the supercharger installation.

When Golden tested the motor on a chassis dyno, the forced induction S54 pumped out 470-hp to the rear wheels at about 7,500-rpm and an equally impressive 331 lb/ft of torque to the wheels. “There was a huge difference in acceleration,” he says. “It made me laugh out loud the first time I drove it.” And the engine’s behavior in stop and go traffic has actually been improved. “It idles even better and more smoothly, and the drivability is near stock.” 

On the road, the Z4M feels like a rocket. It may not have quite the thrust of a turbocharger, but the supercharger’s power delivery pulls like a train. The torque curve is flat as can be. On a cold winter day in fact, the power proves to be a bit much for the sticky R-compound tires, which slither back and forth under heavy doses of throttle in the lower gears. There is a slight whine from the supercharger under aggressive acceleration, but the dominant noise is the raspy howl of the S54 engine, amplified in this case by the Active Autowerke headers and Stromung exhaust. As expected, grip is so high during street driving that there is no way to really probe the limits safely. Despite the massive power increase, Golden’s Z4 appears to have retained an impressive amount of balance in regards to acceleration, handling and braking. Sure, the ride is on the stiff side, but that doesn’t bother Golden: “It's my daily driver- rain, snow, or shine- and track car.”

Supercharged Z4 Exhaust Comparison - OEM vs Supersprint


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