### It’s all about the what?

8/15/2013

Why?

What is the delta?

By definition, *the delta* is the change in any changeable quantity. The delta is what sums up the basis of OEG. It is the quantified measurement of improvement over any number of given points. When you get your engine calibrated / tuned by me, you are getting the greatest delta that I can safely provide over all given rpm points, not just the peak values.

It’s unfortunate that the majority of people have an understanding that a dyno session will only reveal two numbers, maximum horsepower and maximum torque output. My understanding of this is founded from the question that I often recieve after tuning a clients car:

*“What did it make?”*

Now, it should be understood that the maximum power output of an engine is an important piece of data. It can be one of the class selection variables in NASA and SCCA road racing series’. It can put in perspective the overall health of the engine, but it is really only a small fraction of what really matters after a dyno tuning / calibrating session.

Figure 1 is a dyno plot of two similarly modified Nissan GT-R’s.

*It should be noted that these two plots are different cars with different sized turbo chargers, and only the red plot has a properly tuned closed loop boost control algorithm. *

*The point of this article is only to highlight the little amount that “peak numbers” really tell you. *

You’ll notice that the red horsepower and torque plots make a little less power and torque above 6750 RPM, but practically everywhere above 3700 the red plot makes substantially more horsepower and torque. What this means in the end is that the power and torque output that is felt by the driver will be much easier to access being that it makes the greater power and torque numbers at a LOWER rpm.

If you were to focus on the peak numbers alone, you might think that just because the blue plot shows that the engine made 1266 whp it would marginally faster than the engine that only (yes, “only”) made 1084 whp. I would be willing to bet given the same circumstances, that if these two cars were to drag race from a stop that the race would be very close.

*Note, this is just conjecture and the race would depend greatly on gear ratios and shift points. *

Now, what isn’t conjecture is that the red plot will yield a much more enjoyable car to drive. Take a look at the 5000 RPM x-axis column. The red plot is 200 ft/lbs of torque MORE than the blue plot!

The purpose of this is to show that there is so much more to calibrating / tuning an engine than just peak output numbers. I always focus on giving the customer the best outcome at all measurable points. Any questions, concerns, or comments? Please write me from the Contact page, It would be great to hear from you.