The big engine of Jason Taumalolo fires up again as he takes aim at the Roosters' defence.

Jason Taumalolo is pledging to fire up his "turbo diesel" engine for one last drive towards premiership glory after powering North Queensland's incredible journey to the NRL grand final.

Taumalolo promised fans there was fuel left in the tank for Sunday night's blockbuster battle with Melbourne after destroying the Sydney Roosters pack at Sydney's Allianz Stadium in the semifinals.

The Cowboys enforcer racked up 237 metres - 100 metres more than any other player - from 21 runs and also made two tackle busts and 22 tackles in another unstoppable display in the 29-16 demolition.

MARK KOLBE/GETTY IMAGES Plenty of admiring fans pursue Jason Taumalolo after the Cowboys' win over Sydney Roosters.

The added metres brought Taumalolo within touching distance of becoming the first NRL forward to register 5000 running metres in a single season. If he can make just 56m more in the grand final he will break his own record, set in 2016. He's averaging almost 200 metres a game.

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"I think I'm a turbo diesel, so good in short stints, but if I needed to I could go that extra bit longer," Taumalolo said as he fuelled up with a celebratory XXXX Gold in the triumphant Cowboys dressing shed after the semifinal win.

"It's a grand final so I think I'm willing to leave it all out on the field on Sunday night. Honestly, words can't describe how I feel. I think proud would be the biggest word to describe the way the boys have been playing the last few weeks.

"Everyone thought we were here to make up the numbers. Pretty much no one gave us a chance the last three weeks, obviously apart from the boys who took the field."

Taumalolo delighted in leaving his New Zealand test team-mate, Roosters hardman Jared Waerea Hargreaves, eating his words after he'd talked of stopping the Cowboys juggernaut to end North Queensland's dream run.

"There's a lot goes into the hype of finals footy, but there's an old saying: 'if you're not going to do it, then don't say it'," said the reigning Dally M Medallist.

"Obviously Jared, I have that much respect for him and he's a physical guy and great footy player. I knew I had to be at my best if I was to be up to the challenge and I took it to him."

The Cowboys' other superstar JT, injured half Johnathan Thurston, is backing Taumalolo to again produce the goods against Melbourne.

"What he's done tonight, the Storm pack are going to come after him," Thurston said.

"That's where he's at now in his career. He's put himself in this position and that's what happens you start to become the best; you get hunted."

Taumalolo plans on emptying the tank.

"It's been a big season and whatever I have left."