"Built for the 2015 Dodge Challenger SRT, the Hellcat’s foundation is a 90-degree V8 truck block found in Ram heavy-duty pickups. SRT considered developing an aluminum cylinder block, but the cost and durability advantages of the existing iron block were too attractive to ignore.
“Were not saying aluminum was an impossibility,” explains Gregg Black, chief engineer on the Hellcat Hemi project, “but the iron gives us the stiffness that helps prevent distortion under the high cylinder pressures.”
Computer modeling predicted cylinder pressures approaching 1,600 psi. Given that the Hellcat engine sports a 4.09-inch cylinder bore on a 4.46-inch bore centerline, significant strengthening measures would have been necessary on an aluminum block to support those high cylinder pressures.
“We already had a 6.4-liter block with a high duty cycle developed for trucks,” Black tells EngineLabs. “We knew the strength of that block had been upgraded for that program. It made sense to leverage hardware already available.”
While the Hellcat starts with a block that is cast and machined on the same line as a Ram truck engine, the Dodge block, of course, is painted bright Hemi Orange."