This may end up being an unanswerable question, but I'll give it a try anyway...


I have a 2006 JCW convertible and a 2005 S. The JCW is stock while the S is also all stock except for having an ATI 2% damper installed. Both cars run perfectly fine with no drivability issues.


The thing is, off the line my 2005 S is much much faster and has tons of bottom end. In a race the 2005 S will be five car lengths ahead of the JCW after 150 yards. The JCW seems to come alive only in the mid to top end.


I know the ATI damper increases power by 15 to 20 hp, but the difference between my two Minis is significant.


I can certainly live with my JCW being what it is. I'm just wondering if I might need to have the ECU on my JCW re-flashed or, if it is working as it should, possibly have the ECU "tuned" so that it can offer better bottom end power.


What is your expert opinion/suggestion?

 

Have to remember that the vert is pushing 300 lbs heavier. With the 2% overdrive you boost is up there with the JCW and all it has is larger injectors, the exhaust, some polished ports and little better tune. The weight IMO has allot to do with it.

A boost gauge would help allot with the JCW as you may have some leaks around the BPV and/or the throttle body. What is condition of the plugs, air filter etc?

 

New plugs and filters with only 4K miles on them.


To be truthful, it's not so much that my JCW is slow... it actually feels the same as all of the other JCWs I've driven. My guess is that my 2005 S is just naturally a quick car - even more so now that I've added the ATI damper. Off the line it can really set you back in the seat.

 

A 15% reduction supercharger pulley will generate that gain not a 2% ATI crank pulley.

 

Gotta dust my brain off a little but thinking the rule of thumb is that when you increase the boost by 15 PSI you have doubled the horsepower. With an 05 S the HP is 168, so for every 1 PSI of extra boost you gain approximately 11 HP. That is why so many use the 15% pulley as an inexpensive way to pick up horsepower. The boost on a stock S is around 10. From most posts that you will see, with the 15% pulley they are up around 15 PSI.

Remember, these are all general numbers and allot of other things go into the mix such as fuel injectors, exhaust ports etc.

 

It's the weight difference, the convertibles are significantly heavier.