Engine Management

The three main parameters (boost can only be modified on the Cooper S) of engine management that affect performance are:

1. Boost (cramming more air into the cylinders)
2. Timing/Ignition
3. Fuel Ratios

Boost is generated by a supercharger or turbo charger.  A supercharger is different from a Turbo in that the compressor is spun by a belt that is driven off the engine drive train.  On a turbocharger, the compressor is spun by exhaust gases coming out of the engine.

Boost Controllers

Boost controllers are listed here just so you can understand what might happen when a naturally aspirated (115 hp) MINI Cooper is turbocharged.  For information on increasing boost on a Cooper S go to the ?Pulley? section.

The simplest form of engine management to extract more power is a manual boost controller. As its name implies, the boost controller maintains stock or higher levels of boost. As in a "Stage I" application (Exhaust and intake) the boost controller overrides and adjusts turbo boost levels over the engine's entire rpm range. A manual or "solid response" boost controller, however, does NOT adjust/change other engine parameters such as timing or the air/fuel mixture.

You will need a boost gauge to initially set a boost controller.

Pulleys

In order to increase boost (and get more power) you need to get the belt that drive the compressor to increase its speed.  The easiest way to do it is by reducing the size of the engine pulley.

It is easiest to understand when you think about your mountain bike (or your old Schwinn 5 speed :^).  The highest gear?or rather the fastest gear is when the chain is driving the smallest gear.  That means when you reduce the size of the engine pulley, the supercharger compressor will spin faster and create more boost.

A stock MINI Cooper S runs with .8 Bar boost?roughly 11.75 psi (14.7 psi = 1 Bar?to convert Bar to psi, simply multiply bar by 14.7). 

Reduced sized pulleys typically generate an increase in boost of 3-4 psi which roughly translates into 20-25 hp.  Also, there is a noticeable difference in how the engine behaves as the engine will reach higher boost much earlier in the RPM range than stock.

Torque figures go up in a similar manner as well.

Timing and Ignition

Timing is usually expressed in terms of degrees before ?top dead center? (TDC).  Tope Dead Center is when the piston is all the way to the top of the cylinder?or at the top of its cycle.

What timing tells you where the piston is in its up/down cycle when the spark plug fires.

Aggressive timing unlocks more power?to a point.  Timing that is too aggressive leads to detonation.

To set timing and ignition effectively, you need a dyno and a knock detector.  Since no one I know has those lying around in their garage, it is best to let engine management companies that expert and have the necessary tools to determine the best compromise between power and reliability.

These companies (like autothority, GIAC, Conforti, etc.) coined the phrase ?chipped? or ?chip?.  What they really do is to reprogram or modify your stock ECU. 

Some companies produce a separate controller for timing, fuel, and boost.  Other companies produce a ?piggy back? ECU that typically incorporates timing, boost, and air/fuel.

Fuel Controller/Computer

Running too much fuel, especially with increased boost, decreases combustion (not enough air to combust all the fuel) and hence?less power.

A fuel controller/meter can adjust the fuel mapping, allowing the engine to increase its power output. This can be significant or a properly tuned/matched fuel controller combined with a smaller pulley.

Piggyback ECU, ECU "Reflash" & Full ECU Replacement

The next step up in engine management is to either reflash the factory ECU, add a "Piggyback" ECU or a full ECU replacement engine management system.

These computer systems typically incorporate boost control, fuel controller, and add to the mix things like ignition/timing.

With more parameters than just boost pressure, a properly tuned engine management system can have a greater impact on mid-range torque and throttle response with little or no effect on reliability. This is because they have greater control over how the engine performs as a whole and do not need to resort to dangerously high boost or fuel levels as the sole method to make more power.

ECU Reflash

The is becoming the norm in engine management. A programmer is used (it typically plugs in to the OBDII port of your car) to change some of the factory parameters and specifications...like air/fuel ratios and timing. This is a great way to modify your ECU as it continues to utiliize all factory sensors and the factory ECU still has control over non performance items...like climate control, etc.

"Piggyback" ECU's typically add functionality to the factory ECU. The benefit of "Piggyback" ECU's is that the factory ECU typically retains control over the vehicle's vitals. In other words, the factory ECU still reads and uses all factory engine sensors (such as O2) and performs as the factory intended.

In other words, a "Piggy-Back" system usually influences only the "performance" parameters (such as boost, fuel mixture, timing, etc.).

It does this by intercepting the factory ECU signal, sending preprogrammed performance parameters (i.e. boost, timing or fuel), and then "lying" to the factory ECU when sensor information is sent back (no?I am only running 11.7 psi?not 16 psi :^).

A full replacement or stand-alone engine management system (Link, AEM, TEC-II, etc.) allows even greater flexibility. With that flexibility comes complexity, custom fitting, and cost (expect to pay $600-1,200 over a "Piggy-Back" ECU). As you progress further down the power path (monster turbo, custom cams, new fuel systems, etc.) a replacement ECU becomes necessary.