The “Rubber Band” Effect robs you of precious torque!
We all have felt different power curve in various vehicles. Quick transitions from lower to higher torque levels induce risk on lower octane fuel. By limiting transitional spikes, and tapering in and out of torque slightly; risk can be greatly reduced. A great example of this is on the right, the previous tune had these issues:
Under-timed onto boost
Overly-rich onto boost
Timing identical from 2.0 load to 3.5 load (2500-4500)
This creates excessevie EGT’s
Flattens torque curve
Makes boost harder to control
Torque spikes with the boost spike
The result for the user is a very “Rubber Band” style of torque curve. The car “Feels faster“, when actually it’s running identical peak torque to the other map. The difference is with a correct timing curve, the torque builds faster and holds longer. It would be like driving in I mode at all times; with incredibly high boost pressure. This reduces that quick transition to higher torque. This easier transition to and from higher torque helps by:
Driver has better control of the torque application
Cylinder pressure doesn’t spike as drastically
Lower boost levels increase turbocharger efficiency and life
Less wear on drive-train components
We also were able to lower the boost being run on this example by 1.4PSI at peak. This greatly helps reduce the heat soaking of the cooling system. By running lower amounts of boost we can also reduce the risks of over-boosting. If an over-boost event does occur, it would be at a lower amount. This allows us to also drop the over-boost threshold to give us a more tight control over the boost. All of this helps greatly reduce stress on the system. With drive modes in the vehicle we can further tweak the scaling to take advantage of this correct scaling. Running optimal timing and fueling in and out of boost at various drive levels.
Remember a tune is not just the peak torque, high RPM events in a tune. Transitional states are HUGE when calibrating. Don’t let timing flaws, over fueling onto boost, flawed cam phasing and non optimal scaling plague your off and onto boost performance. We are often asked why we love flex-fuel so much. Well simply put, it allows you to have 100% perfect scaling on varying fuel types. With a revolving math equation running at all times in your engine; you want as many constants as possible. To get your vehicle optimized, follow the links below: