Paul Walker crash caused by speeding: investigators

Investigators have concluded that speed was solely to blame for the car crash that killed Paul Walker and a friend.

The Porsche driven by Walker's financial adviser Roger Rodas was travelling at up to 150km/h when it hit a light pole in November, 80km/h above the speed limit, according to investigators with the Los Angeles County Sheriff's Department and California Highway Patrol.

Walker, 40, and Rodas, 38, died at the scene.

The sheriff's department announced its findings on Tuesday, confirming earlier reports that the crash was not caused by mechanical problems with Rodas's 2005 Porsche Carrera GT or debris on the road.

The speed of the Porsche was calculated based on marks that one of the car's tyres left on the road, according to the Associated Press.

Porsche engineers sent to review the mangled and burned wreckage of the car had found no problems with its systems.

"The results of the investigation show that, according to all the available evidence, this crash was caused by dangerous driving at speeds much too high for the road in question," Porsche said in a written statement.

"We stand by our Carrera GT and by the investigation."