Australian horror film duo James Wan and Leigh Whannell have once again proven there's millions of dollars to be made in scaring the pants off audiences.

Their sequel Insidious: Chapter 2, starring fellow Aussie Rose Byrne, cost just $US5 million ($A5.37 million) to make but it topped the North American box office and broke records on the weekend by amassing $US41 million in ticket sales.

It was the second-highest September opening weekend for any film, one of the top debuts ever for a horror film and proved they are among the most profitable filmmakers in Hollywood.

"I just woke up and saw what Insidious 2 did last night," a stunned Wan tweeted.

"I should sleep more."

The film relegated Robert De Niro's new Mafia comedy The Family to a distant second place at the box office with just $US14.5 million in takings.

Insidious only made $US13 million on its opening weekend in 2010, but with Wan's haunted house film, The Conjuring, earlier this year smashing box office records by earning more than $270 million worldwide, the director has built an army of loyal fans.

Director Wan and screenwriter Whannell, both 36, met at film school in Melbourne and had jobs at the ABC before moving to Los Angeles.

They have found the recipe to make low-budget horror films that earn hundreds of millions of dollars.

Their breakthrough came in 2004 with Saw, an ultra-violent and psychologically terrifying horror film that cost $US1 million and went on to collect more than $US100 million in box office and generate six sequels.

Hollywood studio Universal is hoping Wan's magic will continue in a different genre after hiring him to direct Vin Diesel and Paul Walker in Fast and Furious 7.