Sunday, February 19, 2017

Sixty foot failure - Why are magazines afraid to measure in sixty feet?

Recently Jason Fenske of Engineering Explained calculated a clever theoretical zero to sixty miles per hour best-of time using the extreme threshold braking measurement. He used the sixty miles per hour to zero braking distance to calculate the time from 0 to 60mph. The braking shows the grip threshold of the tires. There are some problems with this. First the sixty foot should be the launch measurement. Second 0-60mph is only half the picture with too many variables and becoming moot with all-wheel drive.

Real world results of drag racing with street cars are obtained with the most participatory motorsport in the United States. Hundreds of drag strips across the country host hundreds of racers each on any given weekend or evening weekday. Whether minivans and Honda Civics, Prius or Porsches, and ever-present Camaros and Mustangs, they are all raced and the drivers get a timeslip with their results for each pass.  And on that timeslip is the sixty foot time showing how good the launch was. The magazines don’t do this. Dragstrips don’t measure the 0-60mph time. We have a discrepancy.

The 0-60mph measurement is becoming essentially moot among all wheel drive vehicles. Add more power and the time drops. With 8, 9 and now 10 speed transmissions, more aggressive gearing is even easier to make a vehicle quicker without negating overall mileage. Imagine hitting redline in first and second gear before hitting 60mph in under three seconds. So for all those AWD performance cars, does a 2.2 or a 2.4 second 0-60mph time really matter? Only in a stoplight race across the intersection. And assuming launch control is active, conditions are ideal and if an EV, has a nearly full charge.  But a sixty foot time tells the launch potential. Tesla now has the production car record 0-60mph. And the new 911 Twin Turbo S lifts the front wheels at launch per Motor Trend. What is the 60ft for both of these?

Rear wheel drive cars are not just limited to their street tires and a theoretical traction limit based on their braking distances. Weight distribution and transfer can vary, that is always a given. But surface and tire adhesion can be increased with substances like VHT which as a result decrease potential 60ft times. Also a very popular upgrade for better traction is street legal drag radials (“DRs”). Dodge is making history by equipping the upcoming Hellcat based Demon with DRs for the very purpose of better launch traction and hence a quicker elapsed time at the track.

So the NHRA and dragstrips across the country have been measuring the 60ft, the AWD cars are making the 0-60mph a secondary data point and now a car is coming from the factory with drag radials. A special mention should be made for the Mustang GT which comes with a line lock for allowing rear tire spin to clean and heat them up to make them more sticky. And of course Tesla, despite the only performance metric they excel at, for now having the 0-60mph record and bringing such attention to production car drag racing. Bottom line, the 60 foot time is long overdue for the magazines and needs to be incorporated in their testing.

Footnote:
An initial appeal was originally published on February 3rd, 2013:  http://cartruthblog.blogspot.com/2016/07/what-car-magazines-should-measure-part.html

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