php class in an array

I have a php file where I have an array with some data in classes like this: (in javascript)

array = [
     {engine: "V6",
     capacity: 2.5,
     hp: 300
     }]

I tried to put this into a php file but it gave me 500 error

$array = [{engine => "V6",
     capacity=> 2.5,
     hp=> 300}];

I think I may be doing something wrong over here, could someone confirm?