How could Roush Fenway Racing, one of the top organizations in NASCAR, a group that spends millions of dollars a year on research and development, have an engine failure in the first seven laps of a race for a Ford team coming off back-to-back wins?
How could Hendrick Motorsports, possibly the premier team in the sport, the one that has won the past three Cup championships, have four engine or transmission problems in its Chevrolets the past two weeks?
And how could Toyota Racing Development, a group that knows as much about engine technology as any in the world, have to put a batch of motors in the junk pile thanks to a lubrication issue?
Is there some strange disconnect between the design model and the designers, the NASCAR experts, in making engine power and reliability?
No, these guys haven't lost their cylinder heads. The answer isn't complicated. Too many RPMs and not enough testing have caused a rash of unexpected motor malfunctions.
"Everyone's engines now are so on the razor's edge," said Lee White, president of TRD. "There's no margin built in because the competition is so fierce. The engines have to be perfect."
A lot of engines weren't so perfect at Las Vegas.
Matt Kenseth's motor was clanging metal almost before the Shelby 427 began Sunday. Two of his Roush Fenway Racing teammates -- David Ragan and Carl Edwards -- also had motors die on them before the end of the event.
Kenseth said it was his first engine failure in two years. Ragan never had a previous engine issue at RFR.
"In four years [at RFR], I think this is the first time," Ragan said. "But things like this happen sometimes when you try to get the most out of these engines."
All the RFR engines come from a partnership program with Yates Racing. Doug Yates is considered one of the top engine builders in NASCAR. He was concerned after Sunday's race because the three engine problems weren't similar.
"This is the same package we ran last year," Yates said. "But these cars are getting better, and it's putting us over the limit."
The same thing is happening with some of the Toyota teams and the General Motors engines in the Hendrick Motorsports Chevrolets.
Mark Martin lost an engine for the second consecutive race, an unimaginable occurrence for a Hendrick car.
"Last week [at Fontana, Calif.] we broke a valve spring," Martin said. "I can't understand what happened this time. This stuff [engines at Hendrick] is usually bulletproof."
Toyota officials feel that way about their motors, but they noticed the lifters had wear issues after qualifying at Las Vegas. Four cars changed engines, and most Toyota teams went to a heavier lubricant.
Kyle Busch won Sunday's race in a Toyota, but Joe Gibbs Racing builds its engines with Toyota parts. All the other Toyota teams receive engines built at TRD in Torrance, Calif.
That's great to say, and it's a fantastic sales pitch, but we don't race dynos. There's no way my dyno technicians put the engine through the stress that the crew chiefs and the teams do when they're searching for every last fraction of a second on the racetrack.
"-- Lee White, president of TRD
All engines from each manufacturer are thoroughly tested before they reach a race weekend. Teams have a device called a dynamometer, dyno for short, which measures the power of each engine.
Teams do simulation races with the dynos, including 500-mile tests in the shop. Technicians say they can learn what they need to know about durability from those simulations.
White says it works in theory, but reality is a little different.
"That's great to say, and it's a fantastic sales pitch, but we don't race dynos," White said. "There's no way my dyno technicians put the engine through the stress that the crew chiefs and the teams do when they're searching for every last fraction of a second on the racetrack."
So with NASCAR's testing ban, some teams are learning engine capabilities at the track. And they're asking more from each engine than they did a year ago.
The more the Cup teams learn about the new car, the faster they go. And Goodyear's tires have improved this season, enabling drivers to rev up the engine a little more.
Even two laps of qualifying put a strain on the motor, with engines approaching 10,000 RPMs.
At tracks such as the 1.5-mile oval at Las Vegas, RPMs stay at more than 9,000 for a large portion of the event. Atlanta Motor Speedway, one of the fastest tracks in NASCAR, also will put additional stress on the engines this weekend.
But there's a bigger issue that NASCAR will need to address soon. The carburetors NASCAR teams still use on its engines are dinosaurs. It's like making popcorn in a skillet.
No one wants to admit it, but eventually, NASCAR will have to switch to fuel injection for engines. NASCAR officials have said they don't want to do it because adding the electronics would be harder to police.
Nevertheless, it's an inevitable evolution at some point in the near future.
Crew chiefs say better cars and better tires have increased engine RPMs about 3 percent more than what they were last year. It doesn't sound like much, but 200 to 300 additional RPMs can be the difference between running fast and blowing up.
It's Newton's third law of motion: To every action there is an equal and opposite reaction.
More RPMs is the action. It's that bad reaction part with blown motors that the teams have to figure out.
Terry Blount covers motorsports for ESPN.com. His book, "The Blount Report: NASCAR's Most Overrated and Underrated Drivers, Cars, Teams, and Tracks," was published by Triumph Books and is available in bookstores. Click here to order a copy. Terry can be reached at firstname.lastname@example.org.