Jack and his classmates built a mini steam engine generated by a flywheel using aluminium, steel and brass components they built themselves.
Jack said the model created was a one lunger steam engine which took about four hours a day, for about 18 weeks, to create.
He said the lunger steam engine was decided on because it was customisable, so you could put your own take and style on it.
"It wasn't so hard that people like me who just started engineering couldn't do it, but it still presented a challenge."
He found out the result on Monday, and was "pretty amazed".
"I just like the hands on approach engineering has and you're building something with the equipment provided, and can see the progress as you go."
As part of the competition, a video was made with the steam engine's parts, showing how they fit together and the different standards the parts had to be created to, he said.
The video was filmed and edited by Rotorua Lakes High School student Ben Peacock, 18.
Rotorua Lakes High School engineering teacher Dave Whitby said the competition had seemed like a great motivator for the students and it was a great achievement for Jack who had only taken up engineering this year.
"My thanks to Competenz for setting up such a fabulous competition. We are looking forward to taking part again next year."
Competenz schools and careers manager Joanne Verry said the challenge was designed to build excitement around trade-based subjects and complemented the national curriculum.
"It's a fun way for students to work towards unit standards while gaining exposure to an industry-based challenge."
All finalists were judged against other schools by industry professionals, including representatives from Competenz, and also a public vote.