My s has been treated to the jcw kit, and I have added alta intake, & madness header. Would a big-bore throttle body help even more, and if so, which is currently the best on the market (madness,mania,etc.) they range from 61 to 63 mm bore, vs 58 for stock. Anybody encountered driveability problems?
thankx-

 

Personally, I just don't see what a bigger TB would add to what you already have... might want to look at the MTH software as an upgrade to what you have and pocket all the extra cash!

 

JCW software: if you go w/ an aftermarket software upgrade on top of a Works kit you WILL void the JCW warranty.
- Specifically, a few companies such as Dinan have taken a more responsible position and advised Works owners not to mess w/ the JCW software (knowing full well the hard & fast positon Mini has taken on this matter.)
-Throttle body. One issue you need to be aware of is the sometimes problematic tendency of the big bore bodies to develop a "sticking" butterfly syndrome at WOT: The increased air velocity and vacume can cause the butterfly valve to stick/hang in it's wide open position at very high speeds & WOT. You will notice upon releasing the gas pedal after a high speed run or WOT driving that the thottle seems to have a delayed drop-off response. This "delayed" throttle response (hangover effect) is uncommon but it does happen and it's a pain in the ***.
IMO: The Dinan throttle is the optimum diameter (conservative) for the Cooper S application and the milling is excellent. Will a TB make a difference? Yes but only in terms of the driver having a more agile throttle feel (faster response time) and NOT in measurable terms of increased power (HP/Torque.) I will be adding a Dinan TB to my 04'Works/Dinan car simple because it does contribute to the responsiveness (add's to the driving fun/pleasure factor.)
PS. I have owned several BMW's (E46 M3 among them) that had AM throttle bodies and the gains were ALWAYS pretty subjective (better throttle "feel" but nothing measurable.)

 

"The increased air velocity and vacume can cause the butterfly valve to stick/hang in it's wide open position at very high speeds & WOT. You will notice upon releasing the gas pedal after a high speed run or WOT driving that the thottle seems to have a delayed drop-off response."


If it is a mechanical hangup, I would suspect the bfly shaft return springs, bearings or the fit of the bfly in the bore; all are related to the mfg of the larger bore, which requires some tricky dis-assembly, re-assembly and careful machining.


Compared to stock, a larger bfly has to rotate farther to reduce the airlow the same amount.

 

I have the M7 62MM tb, and am very pleased with the throttle response, and I haven't had any real problems.

 

I my case it seems to have been a spring problem ( I think it was a larger out-sourcing issue that Dinan was having for a while.) Once it was all re-assembled it worked perfectly & was a very nice addition to my car(s).