How do hybrid engines start and stop combustion so efficiently?


Regular gasoline engines might take a few cranks to get started for a lawnmower/generator, a car has its spark plugs that have to turn over. But in a hybrid, combustion just starts and stops so seamlessly.

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The short answer is that they’re designed for it. The starter motor is designed to engage much more frequently and quietly than traditional ICE engines.

Modern engines are a lot lighter to get going

A small 1.5-2L engine has a lot less rotating mass than an older 3L+ engine did. They’re also generally built with lighter materials because we care about weight and the cost isn’t prohibitive since Hybrids are already more expensive, this makes them even easier to get up to speed. We’re also using wayyy thinner oils which are easier to get going, and even thinner when warm.

Basically, making engines light and easy to spin also made them better engines so we did that and as a side effect they start easier

A lawnmower/generator typically has a carburetor, it takes a number of rotations for the gasoline to travel into the cylinder. most modern hybrid engines have a direct fuel injection into the combustion chamber, so no delay.

This question seems a bit misleading. A hybrid is just the mix of different engines like an ICE and an electric motor/ battery. That’s not what makes the ICE start and stop easily. This is done on most newer engines. My 5.3L V8 (not a hybrid) starts and stops nearly seamlessly.

The starter in a hybrid or car with stop/start spin faster than a traditional starter does.

A traditional starter for a car spins the engine at about 500rpm, just enough for it to start.

A hybrid or stop/start equipped starter turns the engine over at about 1000 rpm, which is just over idle speed.