Spec Any HEMI Build In Seconds: The ACE INC V8 Displacement Configurator
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Stop guessing. Start specing.
Every HEMI build starts with the same questions: how many cubic inches will this combo make, what rod length do I need to zero-deck the pistons, and is my rod ratio going to chew up skirts under boost?
We built a free tool that answers all three in real time, right here in your browser. No spreadsheets. No phone calls to the engine builder. Drag the sliders, see the numbers move.
What it does
- Live displacement in cubic inches and liters as you sweep bore and stroke
- Required rod length back-calculated for a true zero-deck assembly
- Rod / stroke ratio with a hard warning below 1.30 (where piston skirt wear gets ugly)
- NA vs Boosted profiles that auto-clamp bore max and minimum compression height to safe values
- Standard 9.30" and Tall 10.25" deck presets that match our actual ACE INC CGI block variants
Why rod ratio matters
Rod-to-stroke ratio is rod length divided by stroke. Below 1.30, the connecting rod sweeps through too steep an angle at mid-stroke. That angle becomes side load on the piston skirts. Side load eats skirts, scuffs cylinder walls, and wastes power as friction. Anything 1.50 to 1.80 is the sweet spot for most performance builds. The configurator color-codes it so you do not have to remember.
Why zero deck matters
Zero deck means the piston crown sits flush with the deck surface at TDC. That is where you want it. Pistons in the hole give up quench and squish. Pistons above deck need extra head gasket thickness to clear, which kills compression. Spec the rod length the configurator gives you and the head gasket does not have to fight the rotating assembly.
Built for our CGI HEMI block
The configurator presets are dialed in for our Gen III HEMI CGI engine block. 9.30" standard deck, 10.25" tall deck, bore options through 4.260". CGI material handles 3000+ HP without cylinder liners, without thermal expansion mismatch, without the cracking issues you get with old-school cast iron.
Drag the sliders. Spec your build. Then come grab the block that handles whatever you spec.
V8 Displacement Configurator
Spec your build. Calculates displacement, required rod length for zero deck, and rod ratio in real time.
Ready to build?
Every CGI HEMI block is designed under the direct oversight of Eric Cunningham, former Chief Engineer at SRT/MOPAR. Vertically integrated, made in the USA, rated 3000+ HP.