There is one sentence that all racers never want to hear: “The motor blew up!”
In drag racing, when those words are uttered it’s often a literal statement: engine parts scattered over a wide area along with a hot engine-oil bath and lots of fire. It really isn’t necessary for a driver to make the announcement; the accompanying massive fireball pretty much tells the tale. These violent events create some of the most visually compelling images in all of motorsports.
For the unfortunate race team, a photo or video of their massive failure often ends up on the front page of the local newspaper and is a good bet to be the lead item on the local TV sports segment. The reality is that although big honkin’ engine explosions and fireballs are used by the sanctioning bodies to sells tickets, by television producers to juice their ratings and by editors to sell magazines, they are dangerous and expensive—very expensive.
There are three items that generally get the blame for massive engine explosions: parts failure, tuner error and driver error.
Most nitro engine builder/tuners will tell you a V-8 engine is really eight separate internal combustion engines tied together to form an engine block. Each one of these individual engines is supposed to work by opening the intake valve, allowing the mixture of compressed air, nitromethane and a little alcohol to fill up the cylinder; then the intake valve closes, the mixture is compressed even more, an electrical spark is introduced and the mixture is ignited, etc. At some point the exhaust valve is supposed to open, relieving the pressure. And the cycle is repeated.
Most of the experts I’ve talked to agree that massive engine explosions often can be traced to valvetrain failure. If the valves don’t open when they’re supposed to, and instead remain closed creating a sealed, pressurized cylinder full of a nitro/alcohol mixture? That’s the very definition of a bomb!
We know the engineering reasons for engine explosions but what about the human factor? We asked some famous tuners and drivers to tell us what causes the dreaded fiery KABOOM!
Check back next time when Drag Racer speaks to some well-known tuners and drivers to get their take on why good engines sometimes go bad.
Text by Jeff Burk
Photos by Jere Alhadeff, Gary Nastase and Marty Reger