VF-Engineering addresses misleading F80 M3 & F82 M4 S55 tuning dynos (correction factors) and the difference between consistency and marketing

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Tuners using inflated peak figures to market with is nothing new. Often times on forums people just look at the peak figures on a dyno to determine which tune is 'bes' and this is a very flawed approach. Pushing an engine too hard just to get an impressive peak number may look nice on the graph but how nice will it feel when something let's go?

There are many tricks tuners employ. One that is popular with a certain tuner is to get the car very hot and induce heak soak for a baseline run. Then the tuner waits until the car has fully cooled down and does a 'cool' tuned run to exaggerate the gain from the baseline.

There are many ways to influence dyno numbers such as using different gears or playing with correction factors and VF-Engineering delves into why consistency is important below.

Now that we're a forum sponsor, I just wanted to make it known that we're here to answer questions, offer feedback, respond to constructive criticism, etc...

Keeping with the theme of the original post, independent 3rd party dyno results are right on par with our advertised gains by design. We've all been personally bothered when you see that the advertised gains for some companies products seem to always be just ever soo slightly out of reach. Understanding that a lot of this is marketing and companies trying to put their best foot forward, we've made it a point to remain slightly more conservative and let the product and customer reviews do more of the talking.

Here's a excerpt from something we wrote recently to address how misleading dyno numbers can be within context. (hope you enjoy!)

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Aside from what people consider to be the more "marketable" numbers, we prefer to use our DynoJet for it's measuring capabilities as it gives us the best ability to overlay multiple runs and look for consistencies or inconsistencies as we push the car in back-to-back-to-back-to-back runs.

The purpose of these multiple run-groups is to track the changes as temperatures increase, or as we make subtle calibration changes for fine tuning. As you can see below, the consistency of our HEX Tuning Stage TWO runs in the sequence below is quite impressive.(5 runs in a row with 30 seconds rest, then a 10 minute rest before runs 6-7.)

Reading the results.While it's pretty common to see single run comparisons, the more run examples the better. The following plots will give you an idea of how a single run on it's own doesn't necessarily mean much without something to compare it to.

Stage ONE - STD Correction | Smoothing 0 - 486HP 529TQ

Stage ONE - STD Correction | Smoothing 5 - 482HP 521TQ

Stage ONE - Uncorrected | Smoothing 5 - 472HP 510TQ

Stage ONE - SAE Correction | Smoothing 5 - 471HP 509TQ

As you can see from the 4 variations of the exact same run above, there is a deviation of as much as 15HP and 20TQ just by changing the correction factor and smoothing.

When Uncorrected, the dyno is purely displaying the power at the wheels asthey are measured by the machine. SAE and STD Correction will adjust the values based on the the relative air temperature, humidity, barometric pressure, etc. at the test site.

EXAMPLE:
SAE is established at 77°F and 0% Humidity.
STD is established at 60°F and 0% Humidity.

On a 90°F day in July with 70% humidity, the Uncorrected horsepower and torque will likely read lower than on a cooler day with less humidity. SAE or SAE Correction will equalize the results as if they were measured at their respective temperature/humidity.

Generally on a warmer day the correction factor will increase the final results, and on a cooler day the results will decrease.

There are plenty of arguments to be made for or against the use of correction factors, but we'll save that conversation for another day. At VF Engineering we prefer to advertise Uncorrected numbers as we feel the results are more accurate when your before and after dyno results may not take place on the same day and under the same conditions.