Map Width Enhancement Groove

A map width enhancement (MWEG) groove is a pathway between the front of the compressor cover and a slot on the inside of the bore, located well behind the leading edge of the compressor wheel. Its purpose is simple and proven: to prevent compressor surge.

Our Patented Tunable Race Cover takes this concept further by allowing the groove size to be adjusted to match an engine’s volumetric efficiency (VE). This design does not create an artificial “cheating” power gain—it’s a tool to:

• Keep the turbocharger out of surge, and

• Shift power delivery within the engine’s powerband (from the front end to the rear).

Standard, non-adjustable map width grooves are typically set between 0.200" and 0.250". However, if an engine’s VE is far from ideal and surge occurs, being able to tune the grooveallows you to eliminate surge and balance performance. For example:

• This adjustability can make engines of very different sizes (e.g., a 6-cylinder vs. a 440ci V8) behave in a similar, surge-free manner.

• In third-party testing with a single 76mm turbo, adjusting the groove was shown to shift 45–50 horsepower from the lower portion of the powerband toward the upper range.

This tuning flexibility provides real-world benefits:

• Engines that lack low-end torque can keep more power early in the band to help get moving.

• Engines with excessive low-end torque can shift power to the top end—where traction is better and the extra horsepower can be put to use more effectively.