We saw Garrett Mitchell might want something like our newest Engine of the Week – It's a 422 cid small block Mopar engine, which might not be something many people see anymore these days, but it still has a strong following among the loyal Mopar crowd. As such, Ken Lazzeri of Indy Cylinder Heads showed us a build they did using the aftermarket R3 Mopar performance block that's capable of 750-800 hp naturally aspirated, and even more if done in a blown configuration. Engine of the Week is sponsor

In the 1970s and early '80s, Mack Trucks teamed up with Garrett AiResearch and KHD to challenge diesel with jet power. The result? The GT-601 gas turbine – a 550hp air-cooled engine that could launch a loaded Mack in top gear without a shake. No winterizing needed, whisper-quiet inside, and just as happy on alcohol as it was on diesel. It roared through 7,000 test hours, scorched leaves from trees, and toured Europe as the future of trucking. But by 1986, improved diesels and tighter regulations