Hi, I just bought a 2008 cabrio JCW (1st gen). Beautiful car that was well taken care of and garaged. 50K miles. Car is essentially a garage queen and 100% stock. The problem is it doesn't feel like a 210hp car. it feels healthy, revs fine, I can hear the supercharger whine but just feels slow. It feels more along the lines of a 150hp. also the boost buildup feels more like a turbo, not the instant super charger torque I was hoping for.

I've owned lots of cars in the past and have built several cars including supercharger and turbo installs and all associated mechanic / maintenance work. I've also tuned ECUs on my cars. I would love some advise on where to start in the debug effort.

Here is what I know so far:
- Max boost is around 12.9psi per OBD2 monitor. This is consistent from run to run
- No CEL / codes
- BPV spring feels healthy. Tugging on it I feel no gap or play.

I've tried to do a bit of searching and reading. What else should I look for?

Here is the car

 

Hmm strange, the power delivery is (near) instant. I drive a Volvo S80 2.4T daily and the Mini R53 JCW for fun and the Mini feels way faster due to its direct nature.

Also the system is quite simple, when compared to turbo. It's almost all mechanics, so troubleshooting it will be easier. I did some searching and it seems the boost figures you see are for a standard MCS and not a JCW. In other words, are you 100% sure that you bought a JCW and not a stock Cooper S with some Works trim?

https://www.northamericanmotoring.co...u-getting.html

 

Ah, I noticed that you created the same thread here > https://www.northamericanmotoring.co...-look-for.html

 

could be belt slippage. I been finding these belt drives are finicky and if not super tight ( this is why I love the Alta tensioner) they don't hold boost or build it correctly.
I would start by smoke testing juuuuuust encase there's a vacuum leak , check the sparkplugs and check the serpentine system..