Cores Are Printed, Molds Are Quoted — Our First HEMI Blocks Are Weeks Away

Why Gray Iron First

These first two blocks are being poured in Class 35 gray iron, not CGI. That's a deliberate choice, not a compromise.

The purpose of this first pour is to lock in our core assembly strategy. We need to validate how the cores locate, how the mold fills, and how the casting comes out dimensionally before we commit CGI material to the process. Class 35 gray iron gives us nearly identical mold flow characteristics to CGI, so the data we collect from these castings translates directly to our CGI pours.

Our CGI equipment is arriving in the next few weeks. Once we've proven out the core assembly and mold flow on these gray iron blocks, we'll move straight into pouring the real CGI blocks with confidence that the process is dialed in. You don't want to troubleshoot core fit and gating on expensive material. Get it right in gray iron, then run CGI knowing the only variable is the metallurgy.

What We're Pouring

Two blocks in this first run: one standard deck height and one tall deck. Each one has a specific job beyond proving the casting process.

Standard Deck — 370 Cubic Inch Supercharged Build

The standard deck block gets machined and built as a 6.2L-style engine at 370 cubic inches with a Kong 2650 Hellcat replacement supercharger on top. Stock cam and lifter setup, positive displacement blower making real boost.

The idea is straightforward: take a combination that's close to production geometry, pile cylinder pressure on it with the Kong blower, and see how the casting responds. That tells us exactly how the block handles sustained thermal load and combustion pressure in a configuration that a lot of HEMI builders are chasing. If you're building a supercharged street car or a bracket car on a 6.2L platform, this is the kind of setup that matters to you, and we want to prove the block in that environment.

Tall Deck — 575 Cubic Inch Clearance Verification

The tall deck block has a different mission. We're building it out as a 575-cubic-inch stroker motor to validate two things: that the 5-inch stroke clears the block, and that the lifter geometry works as designed.

We're running a billet 5-inch stroke crankshaft from Bryant Crankshaft on this one. Bryant makes some of the best cranks in the business. If our tall deck clears a 5-inch stroke billet piece and the lifter bores locate properly for the tall lifter setup, we know the casting is right for the full range of stroker builds the HEMI community is running.

This isn't a power build. It's a validation of stroke clearance and lifter geometry. Every thousandth matters when you're swinging that much stroke, and we'd rather find interference issues on our first casting than have a customer find them on theirs.

The Road to CGI

For anyone following the program, here's where CGI fits into the bigger picture.

Compacted Graphite Iron sits between gray iron and ductile iron in terms of mechanical properties. Compared to the gray iron in a factory HEMI block, CGI gives us roughly 75% higher tensile strength, 45% higher stiffness, and double the fatigue strength. That translates directly to a block that handles boost, RPM, and cylinder pressure better without adding weight.

These gray iron blocks are the proving ground for the process. The CGI blocks that follow are the product. Once the equipment arrives and the core assembly is validated, we'll be pouring CGI HEMI blocks that have never been available as an aftermarket option on the Gen III platform.

What's Next

Once the cores arrive and we pour, the blocks go straight to machining. We'll be documenting the entire process from raw casting to finished, machined block so you can see exactly how these come together.

The standard deck supercharged build will hit the dyno, and the tall deck goes on the measurement table. Both will tell us exactly what we need to know to move into CGI production.

We're building these in the USA, start to finish. That's the plan, and it's happening.

More updates coming as we get closer to pour day.