I just read an article in a Fourwheeler magazine about semi trucks racing in Europe, and trying to see if there'd be any interest in the United States. They said that most use the 11. 1 ltr Detroit In-Line Six. They start with 375hp, and a few engine mods and it's up to 500+hp. If they adjust the turbo they can get upwards of 1000hp. 0-60 in 4 seconds, and this with a 12,000lb truck.
Paul
Paul