Under the Hood: DodgeSRT-4
The combustion chamber is classic pent-roof, with the spark plug in the middle where it belongs. The flat area extending between the intake valves (the bigger ones), and the smaller area hiding behind the exhaust valves would be the quench pads, if the pistons were designed to use them. Engine geeks take note: The intake valves are 34.8mm, the exhaust valves 28.45. For comparison, that's smaller than the 35.65mm intake and 30.65mm exhaust valves in Nissan's QR25. The included angle of the valves is fairly steep, at 48 degrees. This steep valve angle was common in the high-output Japanese four-valve until 10 or 15 years ago, but the newer engines have flatter combustion chambers on the order of 25 degrees. There's good and bad with both designs. Lastly, get this: The exhaust valves are made of Inconel, a hyper-expensive high-nickel steel superalloy designed for the high-stress, high-temperature world of gas turbine blades.
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