Power & torque
Click the chart to inspect that RPM below.
Breathing
Inside the cylinder
VE & MBT tables
Theoretical MBT, not an ignition base map. Each cell shows the spark advance that puts 50% of the burn at 8° ATDC, the phasing for best torque, predicted from flame speed in this chamber. It ignores knock entirely, so real engines run less advance wherever knock limits them, typically at high load and especially on boost.
Volumetric efficiency and theoretical MBT spark advance at every RPM and manifold pressure, from deep vacuum up to peak boost. Each cell is its own engine run with the manifold held at that pressure, so throttling, residual gas, boost scavenging and turbine back pressure all show up. VE is against manifold air density, the speed-density convention.
Compressor map
Estimated from wheel sizes. Your real map beats this.Derived geometry
Compare to dyno data
Paste a dyno pull: columns for RPM plus power and/or torque, separated by commas, tabs or spaces. A header row like RPM, HP, TQ is detected; without one the columns are read as RPM, power, torque.
Set drivetrain loss to 0 for an engine dyno. For a chassis dyno, the pull is scaled up to crank numbers before comparing.
Results table
What the model does
Each RPM point runs one cylinder through repeated 720° cycles until the trapped charge settles. It is a physics model, not a set of correction tables.
Cylinder. First-law energy balance with real gas properties for fresh charge and burned gas, including dissociation at peak temperature. Volume comes from bore, stroke and rod length. Heat loss to the walls uses the Woschni correlation, and the heat released comes from the trapped air and the fuel's heating value, burned at the rate the combustion model below predicts (or along a fixed Wiebe curve if you choose).
Valves. Lift curves are built from your duration at the check lift, max lift and centerlines. Flow area grows with lift and is capped by the port flow coefficient. Flow through the valve is compressible and chokes at sonic speed.
Combustion. The spark lights a small flame kernel at the plug. The flame front grows as a sphere clipped to the chamber, whose height is the instantaneous piston-to-head distance. It entrains unburned charge at the turbulent burning speed: turbulence scales with mean piston speed and the chamber's charge motion, and is amplified by compression. The laminar flame speed comes from the Metghalchi–Keck correlation in pressure, unburned temperature, mixture strength, fuel and residual exhaust gas. Spark timing is solved each cycle so 50% of the burn lands where you set it, and 8° ATDC is used as MBT. Known limitation: the extra advance real engines need at light load is understated, because turbulence here follows piston speed only.
Intake runner and header. Each is solved as a 1-D pipe, so pressure waves travel, reflect at the open end and arrive back at the valve. Ram tuning, reversion and scavenging come out of that solution.
VE. Volumetric efficiency is the trapped air mass divided by what the swept volume would hold at manifold pressure and manifold air temperature, the same reference a speed-density tune uses. Boost raises the manifold density, not the VE. When boosted, the dashed line shows trapped air against outside-air density instead, which is the whole-system figure that goes well past 100%.
Output. Net indicated work is the integral of p dV over the whole cycle, so pumping loss is computed directly. Friction follows a Chen-Flynn form (constant + peak-pressure + piston-speed terms). Brake torque is what remains.
Turbo. At each RPM the compressor and turbine are balanced as the engine cycles converge. Turbine flow comes from the housing A/R and wheel size treated as a nozzle. Its efficiency falls away from the best blade-speed ratio, which is what makes a big turbine lazy down low. Compressor efficiency comes from a simplified map with surge and choke limits. Exhaust gas cools along the port and primary before reaching the turbine. The turbine sits at the end of the exhaust primary as a real boundary, so its work is integrated through every blowdown pulse. The other cylinders sharing that turbine entry feed the manifold at their firing intervals, which is what separates a twin-scroll from a single-scroll or log manifold. The compressor cannot hold pressure left of its surge line, which is what keeps big compressors from boosting at low airflow. The wastegate opens to hold the boost setting, and the resulting exhaust manifold pressure feeds straight back into the engine's pumping loss. In Dyno sweep mode the rotor speed is a state: between sweep points it accelerates on whatever turbine power is left after driving the compressor and filling the intercooler and piping, with rotor inertia estimated from the wheel sizes. A crank-driven supercharger has its drive power taken off the brake output.
Not modeled: knock (on purpose: the timing table is theoretical MBT), variable cam timing, cylinder-to-cylinder interaction in shared plenums and collectors, and measured port or turbo map data. The calibration group holds the knobs to fit against your dyno.