Blow Off Diverter Valve Upgrade - recommended for the MINI Cooper S with increased boost, and for unmodified MINIs in warmer climates. For the Cooper S with the N14 engine 2007-2010.
Fits the following models with the N14 engine:
2007-2010 R56 MINI Cooper S Hardtop
2008-2010 R55 MINI Cooper S Clubman
2009-2010 R57 MINI Cooper S Convertible
This valve is for the BMW Mini 1.6 Turbo engines, as found in the BMW Mini Cooper S Turbo R56/55/57 models with the N14 engines. These are found in the Cooper S 2007-10 or JCW Cooper S 2007-12 . This solution is recommended for any vehicle where the boost pressure has been increased by an ECU software upgrade, and for unmodified vehicles operating in warmer climates, as a solution to the many failures that have occurred.
The most common complaint on the OEM solenoid valve is a split diaphragm, which prevents the valve from opening fully, or not at all. This doesn’t always result in a check engine light as the valve can still be blown open by the boost pressure. We have seen many valves with this problem (see image above). The other problem is that diaphragm retaining ring is made from very thin plastic that goes brittle with heat cycles, and eventually fails. This prevents the diaphragm from sealing with the same problems as mentioned above. This particular failure also results in the valve falling apart upon removal from the turbo; in extreme cases, bits of plastic can enter the turbo and destroy it.
The alternative is a fully engineered solution offering both significantly improved reliability. Our valve is piston based, with no diaphragm to fail, and of all aluminium construction, it replaces the original unit with a pressure/vacuum operated piston valve that still also retains the desirable OEM ECU control over valve actuation. The valve has been proved on the VAG scene for many years. The spring is interchangeable for different levels of boost, and the solenoid is plug and play with the wiring harness, which is included.
Bypass / Recirculation Valve Basics
As you accelerate , the turbo charger vanes are spinning and boost pressure is increased, literally blowing into the engine cylinders. Then when you change gear you take you foot of the accelerator momentarily, select the next gear, and accelerate again. As you take your foot off the accelerator the throttle valve to the engine closes. The problem here is that during this process the turbo is still spinning and the boost pressure that it is producing has no where to go. (This is a bit like putting you hand over a hair dryer so the air cannot get out) What happens at this point is the turbo starts to stall, the spinning vanes slow down (incurring alot of stress) and the boost pressure drops.
When you open the throttle valve again by pushing down on the accelerator (demanding more power) the turbo has lost its momentum, boost pressure and there is a pause or a "Lag" before the engine is producing the required power once again. To combat this loss of power and stress on the turbo, a recirculation or diverter valve is used. On the Mini, when the throttle valve closes, the engine management opens the recirculation route around the turbo. This gives the charge air an alternative route and allows the turbocharger to keep spinning so that when you accelerate again there is no "lag" or waiting period. This system works well and is adopted by nearly all vehicle manufacturers on turbo charged petrol engine applications.
It should be noted that the engine management also uses this valve to decrease engine power when necessary. An example of this is by the (DSC) Dynamic Stability Control system. Although you would not normally hear this occurring, when a blow off adaptor is fitted you may well hear the air being expelled when the DSC operates (going to fast around a bend for example)
NOTE: Some states (like California) have ever tightening requirements for emissions testing and inspections. Always check your current state regulations on compliance for street use before you order.