F40 LeMans
Tarmac Traveler
- Messages
- 304
There are no correction factors or whatsoever in German tests. They measure acceleration from rest (and by rest I mean 0,00 km/h instead of 1-ft-rollout) in both directions and later they only have to average the best runs of each direction.
I don't know much about the dyno-methodes, but one thing's for sure: Insoric is much more different than the standard, "standing" dynos. I btw. think it's much more reliable, since it measures the car's real power at movement.
Thanks DeDe for your answer. 
Unfortunately looking at the Insoric system on the web I found no good informations about its reliability to say it must be more accurate than a Maha dyno and its processor and test procedure: http://tothefloor.com/2015-bmw-m3-a...ed-and-real-world-14-mile-et-and-trap-speeds/Recently the Swiss company Insoric came to our attention with a brilliantly conceived device that attaches to your wheel, captures acceleration and deceleration, and converts this data into wheel horsepower and crank horsepower. Their idea to calculate crank horsepower based on measuring drivetrain losses through physics equations of wind and rolling resistance is simply brilliant.
Here at P1 Motorcars we were so intrigued by this idea we immediately contacted Insoric to ask if we could become their US Distributor.
Here’s video demonstrating their brilliant concept.
This video and the concept looked so good, we immediately fired off a series of emails to get more technical details. Here’s what they told us and can be seen from their documentation:
Input Parameters:
- Velocity capture: Captured from Gyroscope and Accelerometer (not GPS — huh?)!
- Sampling Rate: 10 Hz (equal to vBox, but less accurate without a GPS).
- Wheel Diameter (circumference or diameter, measured or calculated)
- Max RPM (user supplied)
- Gear Ratio (calculated from Wheel Diameter, velocity, and Max RPM).
- Wheel weight (user input without any notion of weight distribution)
- Barometric Pressure (user input)
- Temperature (user input)
Look what’s missing:
- Let’s start with capturing velocity: Using a gyroscope and accelerometer to capture and approximate velocity isn’t accurate. At the end of the day, it’s just an approximation. This is exactly how your BMW Performance Steering wheel works. It’s never going to be accurate compared to using a GPS that can capture velocity within a few hundredths of a MPH.
- SAE/STD/DIN correction.: All of the horsepower correction formulae require temperature, barometer, and humidity (or wet-bulb/dry-bulb). Humidity is missing from the input parameters. Their correction equations will never be accurate.
- Calculating losses due to wheel weight (“equivalent mass”): Like CarTest, Insoric has a one-size-fits-all approach to calculating wheel losses. They don’t have separate input for front/rear tires, and they always seem to assume four wheels (no big deal, just pointing it out). To get more accurate calculations, one would like to know the wheel and tire dimensions, along with approximate weight distributions for each.
- Calculating losses due to aerodynamics: Without frontal area and drag coefficient, these losses can’t be calculated. Insoric RealSpeed doesn’t seem to account for this very significant force.
- Calculating losses due to rolling resistance: This is another of those areas where Insoric dropped the ball. The best physics-based calculations here require tire pressure, and for Insoric that is missing.
- Calculating losses (or increases) due to slope. Insoric says to run their product on a flat road or else it’s not accurate. Without a GPS, you don’t have this data. So just stay on a flat road when testing.
