This photo from Mark Webber's wreck on Sunday in Sao Paolo shows that the Porsche 919 uses a transverse mounted V4 engine. I don't think Porsche ever released that info before (if they did, I just missed it, personally)
edit: naaaa son, the car is fucking ripped in half, homie
at 1:42, you can see the crash
PS: #aussiegrit himself had no more than a concussion, doesn't remember the crash, was kept overnight at the hospital but he was released after just a night.