The Chrysler B and RB engines are a series of big-block V8 gasoline engines introduced in 1958 to replace the Chrysler FirePower (first generation Hemi) engines. The B and RB engines are often referred to as "wedge" engines because they use wedge-shaped combustion chambers; this differentiates them from Chrysler's 426 Hemi big block engines that are typically referred to as "Hemi" or "426 Hemi" due to their hemispherical shaped combustion chambers. The corporation had been seeking a smaller and lighter replacement for its FirePower engines, in part because new styling dictates meant moving the engine forward in the chassis which negatively affected weight distribution.