One can't help but believe that engine builders on the NASCAR Sprint Cup circuit are looking forward to one of those rare off weeks coming up in mid-March. After a rash of engine failures to start the season, a little downtime will probably be welcomed.

Chevrolet was the first to get in on the action when Hendrick Motorsports teammates Mark Martin and Dale Earnhardt Jr. were forced to retire from the race at Fontana with blown motors. Bad valve springs provided by a third-party vendor took the blame for these. In the same race, Kevin Harvick crashed from what was initially thought to be another blown engine. The team later announced that actually the oil cooler had been punctured, which caused Harvick to slip in the oil and crash out of the event.

When the tour rolled into Las Vegas on Friday it was Toyota's turn to feel the pain. Eventual race-winner Kyle Busch was the first to be forced into an engine change, after only logging four laps in the first practice session. By the time the day was done, four other Toyota teams were swapping out engines, three for lubrication problems with the cam lifters and the other for another failed valve spring.

Ford didn't fare much better; the Roush-Fenway Racing team blew up three motors in Sunday's race. Matt Kenseth -- going for three straight victories -- had barely turned a lap until he realized there was a problem. Five laps later he had pulled behind the wall and was done for the day. Then David Ragan went up in smoke, followed shortly thereafter by Martin's second straight blown motor, this time for a broken rod. Carl Edwards almost made it to the finish, retiring with two laps to go.

Jack Roush attributed his teams' failures to a bad car setup, causing broken valves. According to NASCAR.com, the Roush team misjudged the speed increases caused by the new Goodyear tire compound.

"We had a choice of which rear axle ratio to use, and we used the higher of the ratios, and it was 200 RPM more than the other ratio would have been. We just made the wrong choice from a crew chief and from an engineering point of view on that. If we can go back looking at it, I'd say I'd need to have more margin in the engine, and it needs to not be that close to its limit. We'll be wiser going to Atlanta."

Everyone will have to be wiser going to Atlanta. The track is one of the fastest on the circuit of those where engines are unrestricted; topping over 9,000 RPMs on the straights is quite common.

Hey... this is why they run 500 miles.

Kyle Busch picked up the lead with 17 laps to go and held on through a pair of restarts to win the Shelby 427 NASCAR Sprint Cup race at Las Vegas Motor Speedway on Sunday.  By doing so he simultaneously became the first driver to win from the pole and win from the furthest back starting position at Las Vegas.  Busch won the pole position on Friday but started at the rear of the field due to an engine change.

Matt Kenseth's attempt to make history by starting the season with a third consecutive victory quickly went up in smoke on lap 6 after engine failure.  Roush-Fenway teammates David Ragan and Carl Edwards also retired with blown engines, Edwards with just two laps to go.

With six laps to go, Jimmie Johnson crashed in turn two to bring out a race record 14th caution.  On the restart, Busch drove his Toyota away from Jeff Burton and Clint Bowyer to take the checkered flag at his hometrack.  Bowyer passed teammate Burton on the final lap to claim second place.  David Reutimann finished fourth and Bobby Labonte was the top finishing Ford in fifth.

Jeff Gordon rebounded from a blown tire on lap 220 to finish sixth.  Gordon missed pit road coming down for a stop, locked the brakes, and blew out the left front, causing significant body damage.  Rounding out the top ten were Greg Biffle, Brian Vickers, Jamie McMurray and Dale Earnhardt Jr.

Johnson, Biffle, and Burton combined to lead most of the laps.

The circuit moves to the fast Atlanta Motor Speedway next weekend before taking a week off.