What should our "smoothing" be on the Dyno?
 

Hey guys, I posted up my Dynojet numbers on another car forum and one of the members asked me why the smoothing was set at 3. He said it should be at 5. I have no clue about it so I figured I'd post it up here for more info.

Thanks!

Mine is STD 5.

So that's what mine should have been at?

What's the difference between 5 and 3?

2.. :tup:


It just has to do with smoothing out the actual line, if you crank the number down to 1 it will be extremely jagged. The readings happen quickly, and there is always variances. Setting it to 5 smooths the line out, gives you a nicer line.

It's arbitrary. 0 = noisier, 5 = less variance charted. Think of 0 as "raw" and 5 as "normalized". I like 3.

I find STD skews high for N/A cars; I think the over generous correction is more appropriate for FI cars given that there is no good correction factor to account for the change in temp due to boost/intercooling.

For N/A cars, I prefer SAE, which tends to be a bit more conservative.

That said, all of the correction factors are equally valid; it just makes it easier to compare and contrast runs done in different ambient conditions if you use the same correction.

But... check this out http://www.the370z.com/1372982-post62.html

Got it! So the power output stays the same...it's just the line itself becomes more detailed or less detailed.

Well, right.

The range of values in the graph will tend to change a bit with smoothing, because the max values are themsleves just two data points (i.e., hp, tq) that have been plotted, and the smoothing function will eliminate (transform, really) some of those individual points.

Thus, it is possible to go up or down a wee bit in terms of what values are reported, but the whole purpose of the smoothing transformation is to eliminate outlier data points.

The correction factors are different -- they apply a correction formula based on the expected influences of temeprature, air pressure, and humidity. In theory, they allow you to make comparisons between sets of runs taken under diferent ambient conditions.

Different correction factors use slightly different formulas, but they are all defensibly legitimate.

If all you care about is the absolute value of the dynamometer's estimate of hp/tq made on that specific day, just go by uncorrected.

As it turns out, on your last dyno day, the ambient conditions must have been pretty close to what SAE determines to be "normal", because SAE CF was 1.00, the same as uncorrected.