Een snelle en een nóg snellere Z4

[ChrisXL]

[ChrisXL]

Leuk stukje om te lezen uit het Z4 forum:

Quite a fascinating comparison with an outcome that surprised me. The key conclusion is that there are several choices open the prospective (and existing) Z4 owner and it will depend on what you're looking for in a car.

Both Tony (X88Racing) and myself visited Simpson Motorsport yesterday to make some changes to my Alpina plus fit a new supercharger to his Z4 and a new rear exhaust box. Once the work on his car was finished I had the chance to drive it and see how it compared to my Alpina.

Well, in some ways they are quite similar (both being very quick Z4s) but in other ways they are poles apart. The Alpina is all about smooth and wonderfully fluid power delivery with lots of torque throughout the rev range. Tony's Z4 also pulls strongly throughout the revs but not quite as strongly as the Alpina as low revs, as we discovered on one back to back comparison. There's a point during the mid-range where Tony's Z4 pulls extremely hard (rather like a turbocharged car in some ways) and whilst it revs to the red-line, it seems starved of oxygen because it feels a little breathless compared to the Alpina. This gives it the impression of having very close gears (whereas the Alpina is actually geared shorter), since Tony's supercharged Z4 is all about punchy low-mid range that thursts the car forwards quite violently until you get used to it.

For those of you that haven't experience it, I've got an easy way for you to imagine. Pick up a copy of GT4 (If you don't already have one), select a 3.0i Z4 then choose all of the tuning options available included forced induction. Now unlike a turbocharger there's no discernable lag, but otherwise it feels very similar to the game version. Acceleration on a par with a speeded up video game, and the 'darth vader' soundtrack to go with it.

I realise that Tony's next step is to fit cams and improve the top-end breathing and this should provide the final icing on the cake that it needs, but it's currently a high-octane equivalent of a fizzy drink - lots of excitement and drama in a tightly controlled package.

We tried a back to back performance comparison later in the day, but at this point I had a nice CSL front anti-roll bar and Tony had nothing (yes, I mean nothing) on his car. So it was a scary beast to turn into a corner and even scarier under braking. Tony was 2-up whilst I was on my own and the Alpina seemed quicker lower down but both cars similarly matched threafter. But it's not really a fair comparison since it can't have been much fun for Tony with a front-end that had gone AWOL. We know Tony's Z4 is producing around the 380bhp mark so that confirms that the Alpina is comfortably kicking out around the 320bhp on Shell's finest (that's nearly 100bhp more than a 3.0i Z4).

So as I say, there are choices.

The Alpina certainly held it's own in such esteemed company and proves what fantastic value these cars are, but a supercharged Z4 along the lines of Tony's car is about as quick as you could sensibly choose to go in a Z4 and not far off something like a 996 Turbo, for a fraction of the price.

[ChrisXL]

En nu het commentaar van Tony:

Yes, Steve didn't point out that the reason why I didn't have a front anti-roll bar on was that HE HAD IT ON HIS CAR!!!!

I wasn't intending to follow him, but a visitor at Simpsons wanted to sample the car. It was horrific without the anti-roll bar!!! I couldn't use any of the top end power, and that made it difficult chasing Steve - especially as I could barely go around a corner!!!

The worse thing was that I couldn't find the spare CSL anti-roll bar, so had to fit a set of Ground Control roll bars I had lying around - but couldn't find the drop links - so had to make them. Then I discovered my tyre pressures were 6 psi too low, and generally rushed to put everything back on the car so I could get home - it was not almost 8 pm!!!

Result - my car is not quite right and I need to spend some time on setup.

I also drove Steve's car - it is a lovely package really. I hate the styling though, loved the Alpina seats, loved the clutch and gearchange - and it is a great engine. It is not as fast as my car, but really is easily faster than an M3. The passenger in my Z4 is a GT3 owner, and in among the expletives he let out, he said the car felt far quicker than his GT3. I agree!

The new exhaust makes the car sound alot better (ESS back box) and the replacement supercharger from ESS is also far better (the previous one had an annoying rattle). Steve is right - the standard cams are lacking in lift and stopping the engine from using all that the supercharger provides. The gearchange and clutch are also irritating, lacking the lovely tactility of the Alpina. All will be resolved soon!

One funny point steve - the last time you photo'd a car of mine, it was a very similar shot of a metallic grey and sapphire black pair of BMWs - last time it was our CSLs side by side!

Tony.

[pierrez101]

Verhaal komt me heel bekend voor, een grote zuiger motor is over het hele toerengebied gewoon super soepel en gaat vol door tot hoog in de toeren.

Turbo's of Kompresors zitten meestal in een veel kleiner toerengebied maar delen daar veel rakere klappen uit.

Doe mij dus maar de Alpina, maar dan voor de rest qua exterieur als de zwarte , mooi laag en dat grijze muizen grijs vind ik maar niks, net als het nieuwe design van de alpina wielen

[ChrisXL]

Ja de nieuwe Alpina wielen zijn wel een beetje jammer.

De zwarte is een complete ombouw, zit een complete M3 CSL onderstel onder en is nog verder verlaagd. Is een circuit auto aan het worden.

Die Tony is dan ook een race tuner.

De Alpina is al verlaagd ten opzichte van de standaard.

[pierrez101]

Ja weet dat de Alpina al verlaagd is tov origineel, echter niet veel 1-2 cm AFAIK maar lijkt wel op een SUV in vergelijking tot die Z4, wat ligt ie laag

[ChrisXL]

En vreselijk snel!!!!!

[GVfB]

De Alpina Roadster S is 4mm lager dan de "gewone" Z4 met standaard ophanging.

De Alpina Roadster S is 9mm hoger dan een Z4 met ///M ophanging.

De Alpina Roadster S gebruikt dezelfde stabilisatoren als de ///M ophanging (25/19mm).

De Alpina Roadster S gebruikt dezelfde uitlijningswaarden als de gewone ophanging... en hier wordt het interessant. Omdat de Z4 steeds uitgerust is ex works met Runflat banden en de Alpina goede banden heeft (lees: geen RFT's) is het naar mijn mening, en dit wordt bevestigd door de uitlijning van de Alpina, beter om minder negatief camber (-2°15' vs -2°50) in te stellen achteraan. De RFT's hebben immer een stijvere wand.

Momenteel heb ik op mijn zzzz vooraan de E46M stabilisator van 26mm en achteraan de E85 ///M susp stabi van 19mm. Zit achteraan met camber -2°28' en vooraan -1°22'.

Als het wat beter weer wordt, komen de Sachs Sport dempers erop en ga ik eens wat minder negatief camber (ca. -2°15') achteraan en wat meer toespoor vooraan instellen... wordt vervolgd.

[pierrez101]

Lees sowieso geen goede dingen over de RFT's veel te hard en stug! En superzwaar. Had voor Pa op de vijf serie een set originele 18 inches gekocht met 245/40 RFT's. Man wat waren die velgen/banden zwaar

[GVfB]

Ben van 16" RFT naar 18" niet-rft gegaan.... wat een verschil in wegligging en comfort (beter wel te verstaan he )