Supercharged Z4 to Z4M or vice versa

B

Babw

Member
Has anybody done either of these moves?

I've got a fairly special Z4 (that was owned by Jason Plato) with a very high spec in the colour combo I wanted but it's just a standard 3.0i. Now the bug has hit and I feel the need to up the power, brakes, suspension but am I just chasing diminishing returns?

I didn't really consider a Z4M as I also have a low mileage E46 M3 SMG so didn't really want the same engine in the Z4. It seemed more interesting to have the M54 supercharged to provide a different type of power delivery.

I'm having second thoughts....

Would be great to hear from any supercharged Z4 owners or Z4M owners who's driven a supercharged Z4.
 
Just to copy what we spoke about in our PM as others may find it an interesting comparison:

"It's been 5 years since I sold my ESS twin screw 'charged Z4, so the memories are fading. However, it was quicker than a Z4M, 100kg lighter with slightly more power and torque. I also know this as my friend had a Z4M at the time and we did a few "drags". The 3.0 was easily faster, it also had a lot more grunt low down and still made a great noise, I also had the ESS exhaust. I never had a problem with the brakes or suspension, it never felt over powered on the road, but if I was doing it again I'd of fitted a limited slip diff. In the dry traction was never a problem, but it struggled in the wet, but then so does the Z4M I guess. I chose the supercharged route as back in 2006 a Z4M was £45000 vs £18000 for a 3.0, so £5000 for a supercharger made sense. That's very different now, not sure it would make financial sense, only if you want something different and a project.

As for the Z4M, I've only had it a couple of months, but test driven 5 or 6 over the years. In my opinion it has lots more character, feels more special and a offers a better sense of occasion. The engine is a master piece both in the way the power is delivered and the noise! The car feels more raw because of this and begs to be driven harder. I'd argue the interior is also nicer. It feels heavier on the road, but the steering is sharper, still lacks a little feel though.

Dynamically the Z4M will be a let down after your E46 M3, but more fun if that makes sense.
 
I had the opportunity to go side-by-side with a stock M prior to swapping headers and my diff's final drive. It was close, but a decisive victory for the supercharged 3.0i. The Z4M has more down low than a 3.0i with a centrifugal supercharger @ 6 psi (otherwise stock). The supercharged car has more top end. An ESS-equipped car would be faster than both.

However, the combination of the headers and diff swap is absolutely intoxicating. There is plenty down low now (18.6% more torque going from a 3.07 to 3.64). I love the sound. I'd agree with what's written, but would add that the Z4M left a lot on the table with regards to suspension. A Z4M with a proper suspension setup is balanced and gives so much feedback... definitely not a handful like the reviews say about stock cars. I have all kinds of confidence in it. You simply can't ask for more feedback or better handling in a street car without getting into supercars. A non-M will always be held back with its electric steering.

My car has far more character than a stock Z4M. That's a perk of a centrifugal blower - the rush of power as you approach redline, and the hiss of boost with a high rpm impeller that makes for a turbo-like sound. The spits, pops... love it! You really need exhaust mods to fully enjoy either car.
 
jamiez said:
Pics of current z4 please and spec :)
Click to expand...

Sterling grey with red leather interior.
Main spec:
Professional Nav
M sport heated interior and suspension
Bi-xenon
Professional hifi
etc

I love the colour combination, I didn't have the balls to go for red interior in my M3 with silver grey but the red seems to suit the nature of the Z4 more.

Not the best picture but I think this shows the lines off really well.

11405884675_7637386078_z.jpg

gwatson has been a great help with my questions but I think the ultimate question is that does supercharging and upgrading suspension + brakes take the Z4 up a notch in terms of driving experience?

The power and figures are great but it's really also about the overall package.

As said previously, I like the thought of having an alternative BMW engine to another S54. My daily driver is a 550i so having a Z4 supercharged would further diversify the stable. I probably should have tried a Boxster but am a sucker for BMW.
 
Forgot to post, this is our Z4 on a test against the Boxster form a few years ago. It goes pretty well!

[youtube]Pe9tYS9qaK4[/youtube]
 
pokeybritches said:
] My car has far more character than a stock Z4M. That's a perk of a centrifugal blower - the rush of power as you aproach redline, and the hiss of boost with a high rpm impeller that makes for a turbo-like sound. The spits, pops... love it! You really need exhaust mods to fully enjoy either car.
Click to expand...

Agreed, a centrifugal will give more of a rush top end. For reference BabW, this is because a centrifugal generates maximum boost at maximum rpm, so is constantly building in boost, giving the rush. Where as the ESS kit I had was a twin screw, so it generates maximum boost at just 2000rpm right up to the redline, so is much more linear and give for more of a torquey drive.

Final drive is also a nice modification to make on either car, but not necessary on a 'charged car. I'll be keeping my Z4M engine as it is, but will definitely change the final drive from 3.62 to 3.9 or 4.1 at some point. I did this on my M3 track car and it made a noticeable difference.

Both cars need suspension and brakes upgrades if going anywhere near a track.
 
Babw said:
As said previously, I like the thought of having an alternative BMW engine to another S54. My daily driver is a 550i so having a Z4 supercharged would further diversify the stable. I probably should have tried a Boxster but am a sucker for BMW.
Click to expand...

Haha... what good taste you have. I sold my 550i last year :) Here's a picture of my Z4 when supercharged... you'll notice the subtle S after the 3.0 badge :)

DSC00242_zps985cbe56.jpg

550i_2_zps62b138b7.jpg
 
Great choices gwatson!

You seemed to have got the right idea of buying them and moving them on. The only regret about the 550i is that I wish I had waited for a touring to come up, have been keeping an eye out on the AUC site for a while but these are rare beasts.
 
Ha.. you could call it an addiction, on my 18th and 19th cars in 15 years of driving.

Well mine is/was 1 of 7 manual tourings. I fitted an Eisenmann exhaust too it, stunning!!
 
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