Nobody was more stunned by his meteoric rise to junior national champion than teenage go-kart driver John Iafolla himself.

The Port Kembla 15-year-old had always dreamed of claiming honours at the Australian National Sprint Kart Championships, but had previously failed to feature on the sport's biggest stage.

So when he surged from seventh on the grid to take the checkered flag in the National Heavy category, he returned to the pits post-race in a state of shock.

"It was awesome. I couldn't believe it coming in," Iafolla said.

"I have only started to realise it now through the days that have passed.

"I haven't really won much, it was a massive step up from what I have been doing."

Before the win, Iafolla had previously only scored modest victories at club meetings at his home Picton track and a second placing at the NSW Championships in Lismore.

But after a solid weekend of racing at Newcastle, the 15-year-old began to believe he could stage a boilover on the track.

"When I caught second and third and knew first place had gone ahead, that is when I thought, 'I can get this, I can get this'," Iafolla said.

"I just chased him down and got him with three laps to go and just pulled away. I didn't even realise. I just put my head down and didn't look back once."

The art of coming from behind was far from foreign to the young driver throughout the weekend.

He had earlier came from tenth place on the grid to win his Junior Heavy heat and started 14th in the Junior National Light final before racing home into fifth on a maximum grid.

Weeks of hard work had paid off.

"Until we saw the Nationals there, we hadn't race in Newcastle for about two years. About nine weeks prior we said we are going to test and practice every weekend," Iafolla said.