It never fails. When I give a talk about The Science of Speed at a University science department (as opposed to a talk for the public), someone will ask “How can you advocate for NASCAR? They’re the biggest waste of gasoline.”
Or something similar.
I’m going to look at this in two ways. People often confuse how much energy is used with how efficiently energy is used. One way to cut back on energy usage is to use less energy, but it’s also possible to use less energy by using the energy more efficiently.
A NASCAR racecar gets about 4.6 miles per gallon. Or you can think of it as one gallon gets you .217 miles.
Let’s look at the longest race, the Coca-Cola 600.
Assumptions: We’re going to assume the highest possible energy usage
- Assume all 600 miles are run at full speed. That means we’re overestimating the amount of fuel used, because NASCAR racecars generally get about double the mileage under cautions they get under yellow.
- Assume all 43 cars run the full 600 miles (which rarely happens)
Forty-three cars times 600 miles is 25,800 miles. At 4.6 miles per gallon, we need 25,800/4.6 = 5609 gallons of gasoline.
We can check this against the ‘real numbers’ to get an idea how much over estimate this is. In 2015, there were 24,885 miles run, so we’re 915 miles (about 20 gallons) over.
That seems like a lot, right? But you have to put the number in context.
There are 42 gallons of gasoline in a barrel, so that means we used 136.92 billion gallons — 136,000,000,000 gallons — of gasoline.(Side note: This is down from the record high of 142.35 billion
barrels (gallons – thanks, Josh!) of gasoline in 2007.)
We can break that down a little more.
So the total amount of gasoline used in the longest Sprint Cup race comes out to a little more than one second of the nation’s gas use.
In 2015, the total of all Sprint Cup races was 13,826 miles (per racing-reference.info, thanks!). Multiply that by 43 cars and that’s 594,518 miles total. That’s 129,243 gallons of gasoline – equivalent to 30 seconds of the country’s gasoline usage. Even if you multiply that number by 5 to account for practice and testing, we’re still talking a very tiny amount of gasoline.
A recent report by the Texas Transportation Institute notes that the average urban commuter spends 42 hours a year stuck in traffic jams. About 3 billion gallons of gasoline and 6.9 billion hours were wasted sitting in traffic in 2014. So if we’re talking wasteful, there are far bigger targets to aim for.
And if you want to compare to other sports, examine how much water it takes to maintain a golf course in Southern California or the sum total energy usage
Noticed how it’s really hard to find 100-W incandescent light bulbs? They’re being phased out because they are just darned energy inefficient. Incandescent bulbs work by running current through a metal (often tungsten) filament. The problem is that 85-90% of the energy that goes into a light bulb comes out as heat. Ever tried to change out light bulbs right after one’s gone out? They’re hot.
The lumens per Watt of a light bulb measures how much light is produced for each Watt of power used. The graph to the right compares Light Emitting Diodes (LEDs), Compact Fluorescent Lights (CFLs) and Incandescent bulbs. The number at the bottom is the Wattage for the incandescent, just because that’s how most of us think about lighting.
You can see from this that incandescents are significantly (4 to 10 times) less efficient than the CFLs or the LEDs. If they get the same amount of power, the LED will put out more light than either the CFL or the LED.
How does this apply to NASCAR? A NASCAR engine builder told me that a NASCAR engine under full throttle uses 28 times the amount of gas a passenger car going 40 mph uses.
But it creates 32 times more power. (And that was before EFI, so it’s probably higher now.) The question isn’t how much energy you use, it’s how much of the energy from the gasoline get turned into speed and how much is lost to friction and heat.
A NASCAR engine is more efficient than a passenger car. The whole point of racing is to go faster than anyone else. Since everyone has the same engine parameters, a lot of the work engine builders do focuses on how to make the engine more efficient and get more power out of the gasoline going in.
How do they do this? Lots and lots of ways, among them:
- Lower viscosity oil, to decrease friction
- Lots more oil than in a passenger car to take heat away from the engine faster (hot engine is less efficient)
- Coatings on
- piston skirts
- crankshaft coatings
- cylinder inserts
- and more
Let’s look at valves. The material from which valves are made is regulated (titanium, thank you, to keep costs low), but there are not regulations as to what kinds of coatings you can use on the valves.
Most coatings (anywhere in the engine) are designed to manage either friction (decrease it), wear (decrease it) or heat (direct it to where it’s needed, protect from where you don’t want it, or to help dissipate it). Coatings are very, very thin. We’re talking microns or tens of microns, depends on the application and the coating being used. To compare, the average human hair is 50-70 microns. If you’re more of an English units type of person, we’re talking 100 millionths of an inch.
A typical valve might have three or more coatings.
- a ceramic on the flat (the part that faces the combustion chamber) for thermal insulation
- a hard coating on the dome to protect from valve seat recession (more of a problem since gasoline went unleaded)
- a low-friction coating on the stem
The trick is getting the coatings to stick. This often requires buffer layers to improve adhesion (sort of like primer for making your paint stick). There are people who do nothing but research how to make coatings stick to different types of metals, how to coat parts with complicated shapes, etc.
And there’s a whole ‘nother industry of people who analyze why coatings don’t work. One of these places is Metallurgical Technologies, and given that they’re located in Mooresville, NC, it’s probably not surprising that they do a lot of work for the motorsports industry. (They’ve worked with ECR Engines, GM Racing and Joe Gibbs Racing to name a few.)
The figures above (from their website) show a valve that failed and was brought to the company for them to figure out what happened so that whoever coated the valves could fix it. In this case, the coating started to pit. If you look at their website, you’ll see Scanning Electron Microscope pictures that show the pitting on a micron-scale.
Among the many coatings used in the motorsports industry is Titanium Nitride (TiN), which wears three times less than steel and has less than half the coefficient of friction. If you’ve seen the gold-colored drill bits at the home improvement stores, you’ve seen TiN coatings. TiN helps the drill bits retain their edges and last longer. TiN is also used in hip replacement implants and other medical tools.
Another popular coating is diamond-like carbon (DLC), which gives you ten times less wear than TiN and two-thirds of the coefficient of friction. You may remember that carbon can be as soft as graphite or as hard as diamond. DLC is sort of the Goldilocks material, which makes it wear well and decrease friction. It is not pretty – you wouldn’t make jewelry out of it.
These coatings are a large part of the reason why NASCAR engines are actually more efficient than passenger car engines. So why aren’t they implemented in passenger car engines? Cost. The coatings are deposited by placing the parts in a vacuum and turning your coating into a vapor (or plasma) so they can make a uniform film on the parts. The potential savings for the consumer is offset by how much more expensive it would make the car.
But the more we learn about coatings, the more we develop easier ways of putting them on car parts, the more you’re likely to see coatings more and more in the passenger car industry, making those cars more efficient.
But probably still not as efficient as race cars.