Enter bore, stroke, and chamber specs once — displacement, compression, power estimate, and induction sizing all update together.
Mean piston speed (ft/min) = stroke × RPM ÷ 6. It's a real, widely-used ceiling check — not a prediction of your actual peak-power RPM, which also depends on heads/cam/intake tuning length we don't model. The suggested range assumes a mild-to-moderate street VE window (3800-4400 ft/min); race combos with the parts to back it up regularly run higher. The max-RPM check below is flagged against your piston type from section 04 — cast/hypereutectic parts tolerate less than forged.
Rolls up block + heads + crank + rods + pistons + intake, entered across sections 02/04/06, plus a fixed allowance for accessories, fasteners, and gaskets. Doesn't overwrite the field above — copy it over yourself if you want it as the working number.
Bore/stroke over ~1.0 favors high-RPM breathing; well under 1.0 favors low-end torque.
Per-port flow at .500" lift — the number every head spec sheet leads with.
Port shape and size are reference/sanity-check info — pick a shape to load a typical width/height, then dial in your own custom size. The flow numbers above stay the authority on breathing capacity; the animation speed is just for feel, not a new model.
—
—
More duration/lift shifts power higher in the RPM range and softens low-end VE.
Rod ratio: 1.4-1.6 is tighter/more angular, 1.6-1.8 is typical, 1.8+ favors high RPM and less side load. The computed intake close assumes duration is split evenly around the centerline — real cams aren't always symmetric, so a several-degree gap from your entered ABDC value above is normal; a huge gap is worth double-checking against the card.
Optional: if you know these real measured/catalog numbers, this backs into deck clearance from first principles (deck height − (crank throw + rod + comp height)) instead of guessing it — copy the result into "Deck clearance" above if it looks right.
Pistons + rods scale with cylinder count from Shared Specs; crank is one piece. Feeds the weight rollup back in section 00.
Ignition quality is a separate RPM ceiling from the valvetrain one in section 03 — weak spark energy or dwell shows up as a misfire before anything mechanical lets go. Crank trigger and coil-near-plug skip distributor gear/shaft wear entirely. Plug gap checks against your power adder in section 07 — boost and big nitrous shots want a tighter gap.
Carb CFM = CID × max RPM × VE ÷ 3456. Bigger isn't always better — an oversized carb hurts throttle response and low-speed signal. Running injection? The CFM figures are still a useful equivalent-airflow reference.
—
| Use case | Assumed VE | Recommended CFM |
|---|
Boost multiplier ≈ 1 + (psi ÷ 14.7) × an efficiency factor. Nitrous is a flat HP add once it's on.