- via thermostat is [i] steel-piped next to & heat is transferred into rocker cover's breather hose formatting link, this heated air is then sucked through PCV valve & into intake manifold.chamber [ii] rubber-hosed into bottom of throttle bodyformatting link, & heat flows into the air passing throttle. Both designs make air intake & cylinder head unduly hotformatting link: whenever intake manifold heats up ( esp in long trips ), torque drops & warm-starts are difficult , both because hot air cannot expand much when heated. Ideal temperature of air to receive injectors' spray of petrol is just 40°C =
104°F (