The tanker explosion climax in his latest blockbuster action film "Dhurandhar 2" used 500 liters (around 130 gallons) of petrol along with explosives in a carefully orchestrated stunt involving star Ranveer Singh.
"The fragments and fires were 100% real," Tyagi, 48, told Agence France-Presse (AFP) in an interview.
The sequence reflects a growing trend among Indian filmmakers to deploy special effects, looking to deliver the type of authenticity that computer-generated imagery often cannot replicate.
To create the explosion, Tyagi's team used a real train as a base, constructing the tanker with acrylic panels mounted on a metal frame.
"Because acrylic melts into the air, that's why we see fragments flying," Tyagi said.
"Sometimes, to give a real look, we have to use something artificial."
Also an arms specialist, the shelves at Tyagi's warehouse in a Mumbai suburb are stacked with AK-47s, sniper rifles and rocket launchers, which he supplies as props for movie sets in India and abroad.
His company has worked on productions including the Oscar-winning "Slumdog Millionaire," "Zero Dark Thirty," the Netflix hit "Extraction," Salman Khan's "Tiger" franchise and Shah Rukh Khan's "Pathaan" and "Jawan."
"Our core expertise lies in executing real, controlled effects, from firearms to large-scale explosions," said Tyagi, showing burn scars on his hand from a recent shoot.
Tyagi inherited the profession and the passion for it from his father Mahendra Tyagi, who moved to Mumbai from Uttar Pradesh state in the 1970s.
Starting with small acting roles, the elder Tyagi gradually set up a business supplying prop guns to the industry.
As a child, his son spent his days surrounded by guns and explosives on movie sets.
"I was always excited about new guns and how they operated. There was nothing else that I wanted to do," said Vishal Tyagi.
His father later died in a studio fire, but Tyagi was not deterred.
"I wanted to pursue this career in the correct manner," he said.
"A lot of times I don't get paid as much as the work deserves because some filmmakers don't have that kind of budget, but I never compromise on quality. It's my passion."
Despite rapid advances in artificial intelligence, Tyagi says technology cannot replace practical special effects.
"AI is not creating anything new. It will show you only what you feed into the system, so there is no threat," he said.
"We are dealing with nature. Fire is nature. Smoke is nature. Rain is nature. Technology cannot compete with nature because nature is unpredictable."
For Tyagi, that unpredictability is what audiences appreciate on screen.
The biggest challenge, he says, is that Bollywood often expects special effects crews to deliver Hollywood-scale results with only a fraction of the preparation.
He points to the explosion scene in the James Bond film "Spectre," which took weeks of planning and testing before cameras rolled.
"We don't get that kind of time here," he said. "Here we are always on gas."
His crew follows strict safety protocols, with restrictions on mobile phones and walkie-talkies that can trigger detonations, but risks remain.
Tyagi recalled a recent accident on a set in Chennai in which one worker was killed when diesel tanks exploded.
And on the set of Shah Rukh's upcoming flick "King," where Tyagi was injured while executing a scene involving 1,200 litres of petrol, he said heat from the massive explosion burned his hand despite precautions.
"I should have left the spot, but I waited until the whole blast was over so that the shot didn't get ruined," he said.
"Every day is a learning process."
