BOOST CONTROL

Perfect Power Articles.

 

This applies to Turbochargers only. Superchargers can’t be boost controlled. Boost control was traditionally performed by a ‘waste gate’ canister: a little canister connected to the manifold. When the boost pressure is too high it opens the waste gate, and more exhaust gases are wasted. Simple and effective! But these devices required that the engine is decompressed, which results in ‘turbo lag’.


Modern engines are not decompressed, but use a sophisticated control that regulates the boost pressure to acceptable levels. Acceptable means: Maximum power without detonation! Boost control can be performed by the XMS4 Stand Alone and SMT8 piggy-back product range.


Detonation (Knocking) is mostly experienced between 2000-3000 RPM, when the turbo is full on speed, and the engine has a reasonable good airflow. By reducing the turbo boost at this point and increasing it gradually at higher RPM’s the turbo lag is eliminated and drive-ability is greatly enhanced by an almost flat torque curve.


The boost can be increased at higher RPM’s because the airflow into the cylinders gets worse and the cylinders don’t fill anymore. If one is really smart (and some car manufacturers have done it) one can tune the engine to an ‘almost flat’ torque curve. Of course you need to bring in the turbo boost as soon as the airflow is not so perfect anymore. This requires a good turbo selection and the electronic control provided by the XMS4 Stand Alone and SMT8 piggy-back product range.


HOW IS IT DONE?

A waste gate with the ‘lowest acceptable’ pressure is used. Lowest acceptable means 0.2 to 0.3 Bar. This is the boost pressure at which the engine does not detonate. Then an air solenoid is employed, which allows partial manifold pressure to reach the waste gate. This solenoid is pulsed with a PWM signal (directly driven by XMS4 and SMT8 units). The solenoid bleeds the airflow to the waste gate canister, thus allowing more boost pressure than the waste gate pressure.


The setting up is sometimes a little cumbersome because it depends on the bleed solenoid and the airflow restriction to the canister.

 

 

THE FOLLOWING PERFECT POWER PRODUCTS CAN DO BOOST CONTROL:

 

VISIT THE FOLLOWING LINKS FOR MORE INFORMATION ON BOOST CONTROL: