The Three Lions head into the fourth ODI in Dunedin on Wednesday with a 2-1 series lead after Curran and Chris Woakes held their nerve with the ball in a dramatic finish in Wellington on Sunday.
Curran, 22, went for just seven runs in the 49th over of the match and the seamer claims he has more slower ball variations up his sleeve as he targets a place in England’s side for the World Cup in 2019.
“You have time in training to get a feel for all these different slower balls – and if you don’t try them, you’re not going to learn,” Curran said.
“It’s a gut instinct, and out there I make a decision and commit to it.
"I’m practising all the time, trying these new ones. There’s obviously the knuckle ball, and there’s other slower balls that are coming out.
“In games at the moment, I’m just using the two. But there’ll be a couple more interesting ones coming out for the season – a work in progress.
“I think you’ve just got to try things. A couple of years ago I just started practising different types of slower balls from the back of the hand, and they seemed to work.
“A combination of that and the off-cutter seems to be coming off.”
After conceding just 31 runs in his final four overs, Curran responded to the nod from captain Eoin Morgan at the end of New Zealand’s innings in Wellington, at a time when Mark Wood or Ben Stokes also had overs left in hand.
The Surrey man, who has been given an extended run in the side on this tour due to Liam Plunkett’s hamstring strain, was delighted to contribute to the victory and now hopes to push his longer-term credentials for the white-ball side.
“Getting over the line with the win on Sunday was very satisfying,” Curran added.
“I’ve done it a lot of times in training and I’ve had time to implement it in games at Surrey and a few games for England, so it’s just about going out there and backing myself.
“When it comes off because of the hours you put in practising, it’s very satisfying.
“[The World Cup] is 15 months away, so I’ll finish this tour, go back, do my thing for Surrey and hope to give Morgs a tough selection problem.
“That’s exciting – it’s a great place to be in.
“It’s about me putting my hand up and performing when I do get given a chance.”
Follow all the latest news from England's tour of New Zealand HERE.