Haven't been on here for some time (to post anyway) but figured I'd make the exception to add some words and opinions to Evolve's post
So yes, I noticed the other week that
Woots was thinking of letting his Evolve prototype airbox go soon (as he is returning his to stock for now) so shot him a PM straight away. Did a deal and had the work done just over a week ago. Now the Z is no longer my daily (hasn't been for some time tbh), and in fact is more of just a trackday whore these days, with the occasional meet/show thrown in
Suffice to say though that the addition of the airbox returned the Z to daily commute duties for a few days, as the sound of the thing is rather intoxicating and I couldn't let it just sit there on the driveway doing nothing!
So impressions from the driver? I would say this mod is very, very worthwhile to anyone even thinking of trying to extrapolate performance from their Z4M. Yes, you can go down the route of forced induction of course, but sometimes there is more to the way a car drives than just a raw headline power figure. There is something pure about an NA engine, not to mention this modification is just so straightforward. It took the guys about 60 minutes to install and then another 60 to modify the mapping and get it on the dyno.
So the important things first. Performance. The power curve is arrow straight all the way to the redline. No flatspots, lumpiness, or any hesitation. Just raw pace and the relentless consummation of any road or track ahead of you. Throttle response is also sharpened to almost telepathic levels. It's not like the Zs really suffered from being sluggish to respond; the S54 feels every inch a tamed race motor even in stock form, but the combination of this air box and map make it feel like the throttle linkages have been hardwired to your cerebral cortex. Every single demand you make of the engine's attitude is delivered as you think it, the intake barking back to the affirmative.
And that bark. If this thing doesn't make you feel like you're in a GT or Cup racer from the word go then I don't know what will. It may as well have open throttle bodies/velocity stacks. It breathes hard and loud! Under 3k it's relatively tame. This isn't a bad thing, as it keeps the car subtle enough to drive slowly around town, if my Z was subtle in the first place (but it may be important to some!). The only tell-tale at this stage is an increased sucking-air sound on a light throttle, and slightly gruffer induction, but I would say no louder than any other intake or the Gruppe-M I had before this. From 3k though, on anything from 50% throttle or more, all hell breaks lose. The once muted engine suddenly finds its voice and fills the cabin with a hammering induction note, as if the fuel were now being injected by Railgun instead of Bosch 440s. This increases in speed and pitch until you reach the upper 5000's where it takes on a different tone, seemingly pulverising the cylinders into submission and releasing the battle cries of all six of the forged pistons into a howling wail all the way to 8000rpm, whereupon there is a just a moments silence, as the clutch is dipped, the revs fall and the next gear is engaged ready for it all to begin again!
I shot a little bit of video from a trackday I was on last Friday. It really doesn't do it justice mind you, but hopefully it gives you an idea (plus it gives me somewhere to post this video
). I will try and do some exterior shots shortly as well, and maybe drop them into a comparison video with some of my old Gruppe-M fly-bys. Anyway, here's the link:
Cadwell Park
So, as you can tell I'm pretty happy with the box so far. However there are a couple of minor issues that have been mentioned on here already I believe, that I want to just add my 10p worth to.
There is a minor cold-start issue. It's not really anything more than an inconvenience and a bit of weirdness, but basically results in the engine revs "hunting" when you depress the brake pedal when the car is first fired up from cold. I would say it is in obscure vacuum problem of some kind, and it only happens for the first 30 seconds or so? Indeed, if you drive the car off immediately, and depress the brake a few moments later it has already stopped doing it, and it never happens once its past this point.
Secondly, and I believe this was mentioned by
fullera on a couple of the other threads about this box already, but you cannot heel-and-toe since the new map was uploaded. For whatever reason, it appears as soon as you apply the brakes, the throttle is disabled. Nothing happens no matter how hard you prod it, nada. Now for most people this wouldn't pose much of a problem I guess, but if you're tracking your Z4 then this could be a major concern. I was definitely surprised when I found this out. Not being able to balance the car under breaking and down-change into a corner kind of takes away any advantage you might achieve down the straights from the extra power! :P I've already spoken to Imran on Friday whilst at the track though about this, and dropped Sal who does the mapping an email, and fully expect them to come up with a solution and amendment to the map shortly
Other than these (for some very minor) issues, which will likely be ironed out shortly, I've got nothing but praise for this modification. I'm impressed with what has been achieved, and trust the backup the Evolve guys give their products. I'll update shortly on the issues above, especially the brake/throttle problem, as this is particularly important to me since my car spends a lot of its time on track.
Overall though, a big thumbs up!