FRANKLIN TOWNSHIP – Nearly all the internal combustion teams entered in this year’s SAE Clean Snowmobile Challenge passed inspection Monday, with only minor tinkering ahead of them before the endurance run to Copper Harbor Tuesday morning. They were facing a challenge they hadn’t expected, though – high temperatures, sloppy snow conditions, and even the possibility of heavy rain.

“Tomorrow’s going to be miserable,” said Chad Smith, who will be riding Tech’s internal combustion sled. “I brought my rain gear.”

They’ll also be facing a less-obvious challenge, but one they have been working hard on in the months leading up to the event.

The rules change a little bit every year, said Jay Meldrum, executive director of Tech’s Keweenaw Research Center and lead organizer of the challenge. This year, teams had to design their engines to run on flex-fuel, a high-ethanol mix of gasoline, but won’t be told until after the event what the actual mix of ethanol was, meaning they need to build versatility into engine designs.

“They get better, so I make it harder,” said Meldrum.

Meldrum said the Clean Snowmobile Challenge is also the only event on this year’s Society for Automotive Engineers collegiate design schedule that requires teams to meet federal emissions and noise standards.

“You have to meet standards, or you can’t win,” he said.