UPDATE: The fruits of the labor. More media coming soon.
Original Post:
I got my Z4MC back today. I've only put about 40 miles on it with the kit, but these are my immediate impressions and questions for guys who already have the VT2-500.
The Build:
- Installation was apparently quite challenging. This was Alekshops' first S54 VT kit, though Aleks has done numerous S65 kits. Fitting the parts was challenging to say the least, but Aleks went above and beyond spending the time to make it right. It took him 3 hours to get one particular intake pipe to join smoothly. There is no doubt it took longer than the ~13 hours I was quoted, but Aleks stuck by his estimate even though he replaced all the plastic BMW fasteners with new ones.
- Don't forget to change the crankshaft pulley! Roffle Waffle missed this because it wasn't in the instructions; Aleks missed it because he wasn't even sent the part, in addition to it not being in the instructions. So unfortunately for now I am running with the stock pulley, which results in an indeterminately lower supercharger boost pressure. ESS has already stepped in to remedy the mistake at no cost, but since I am leaving for SoCal on Saturday, the work will probably be done there.
The Drive:
- The S/C wasn't too noisy at first, but now that it has broken in somewhat, it definitely sounds like the bucket of bolts that others warned it would during the break-in period. Honestly you could mistake the car for an idling diesel.
- Probably due to the pulley not driving the S/C as fast as it should, the whine of the charger is subtle, but oh-so-satisfying. In order to hear it with the windows up, I need to exceed about 3kRPM with the engine under only light load.
- The tune is still rough, but there is no doubt that as an Alpha-N system, it is still learning after a mere 40 miles of driving. The idle wavers a bit a times and especially after letting off the throttle while still in gear, the output of the engine is uneven and wavers a bit. I'm pretty confident these issues will go away with more driving, and also that they are exacerbated by the wrong S/C drive ratio.
- Despite the lower boost pressure and recently-reset DME, the car roars like a banshee at WOT from 3k to 4.5k! (At this stage of break-in I am avoiding higher RPMs) The power improvement is already apparent by 2kRPM, and the car gets away from you pretty easily in 1st gear. I'm used to N/A or Turbo, not the supercharger--so having boost when just casually going through 1st without high load is new to me!
Questions:
- The bypass valve makes a little whistle noise at the exact point where air starts to flow through it, so it is actually possible to be at an RPM/throttle level combination where the whistle is constant. I find the noise extremely ricey and annoying, already. At the engine speeds I have been operating at so far, I've not heard any desirable noises from the BPV yet, even with the windows down; certainly nothing like the refreshing "woosh" of a straight-out BOV. Beedub, others--does your BPV whistle at the tipping point?
- How long did it take your DME to adapt after installing the VT2-500?
Here's a video of the car at idle, complete with the noisy S/C and drifting idle towards the end:
More videos and photos to come in this thread in the future!