# How efficient can an engine be?

Contents

Modern gasoline engines have a maximum thermal efficiency of more than 50%, but road legal cars are only about 20% to 35% when used to power a car. … A gasoline engine burns a mix of gasoline and air, consisting of a range of about twelve to eighteen parts (by weight) of air to one part of fuel (by weight).

## Is it possible to build an engine that is 100% efficient?

It is impossible for heat engines to achieve 100% thermal efficiency () according to the Second law of thermodynamics. This is impossible because some waste heat is always produced produced in a heat engine, shown in Figure 1 by the term.

## What percentage of fuel is burned in an engine?

An accompanying graphic notes that a gas engine alone loses 68 to 72 percent of the total power in things like friction (3 percent) and pumping losses (4 percent). Heat losses through the radiator and the tailpipe add up to 58 to 62 percent of the total losses while driving a gasoline-powered car.

## Why is it impossible to design a 100% efficient machine?

Explanation: No machine is free from the effects of gravity, and even with wonderful lubrication, friction always exists. The energy a machine produces is always less than the energy put into it (energy input). … That is why 100% efficiency in machines shall not be possible.

## What is the efficiency formula?

Efficiency is often measured as the ratio of useful output to total input, which can be expressed with the mathematical formula r=P/C, where P is the amount of useful output (“product”) produced per the amount C (“cost”) of resources consumed.