Look for any late 80s or early 90s non turbo volvo at the junkyard. It will have a dual intake with a thermostatic flap attached to the bottom of airbox. One side takes hot air from the exhaust, the other takes cold air from the grill. Set up manual control for it and you're in business. Most volvo owners disable the hot air side completely in order to improve fuel economy, power and emissions. But to each his own.
