I'm curious about how regenerative braking works with a traditional Hemi engine. Specifically, how is the captured kinetic energy stored and then used to assist the combustion cycles? What control strategies are usually used to balance electric torque and raw engine output without affecting drivability? Any insights or resources would be helpful.
How does regenerative braking integrate with a traditional Hemi engine?
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I’ve actually done a small hybrid retrofit on a 5.7L Hemi for a project car, so I can share the practical details. The key is to add an electric motor-generator on the front (or rear) driveshaft and a modest-sized high-voltage lithium-ion pack—usually around 2 kWh is enough to give a noticeable boost without adding too much weight. When you brake, the motor-generator acts as a generator, feeding the pack via a bidirectional DC-DC converter; the kinetic energy is captured as electricity, not as heat. On the throttle side, the controller blends the electric torque with the engine’s torque using a torque-by-torque strategy: the electric motor provides up to 30% of the total output at low RPMs, filling in the Hemi’s torque dip, while the engine takes over as you climb the rev range. A simple torque-request map, updated every 10 ms, keeps the combined output smooth and prevents jerky transitions. In practice, I’ve found that a basic PID loop that limits the electric motor’s contribution to the engine’s current torque output—derived from the crankshaft position sensor—keeps drivability solid and avoids any “surge” feeling during shift points.