Often when we set out to buy a generator we are in the grip of doubts about which engine type is most advisable to install in the generator set that we are going to acquire. Decanting for a diesel engine or a gasoline engine is an important factor to take into account before making this investment if we do not want to take unexpected surprises later.

In general terms and in economic terms, we can apply the same principles that apply to vehicles or any machinery with diesel or gasoline engine, ie for a sporadic or punctual use is recommended a gasoline engine, while for a constant use or prolonged we should opt for a diesel engine, although we should not forget other factors as we will explain later.

However we see in depth that advantages and disadvantages offer each of these options.


In order to clarify the analysis we will divide the comparative in the following points: price, duration and breakdowns, fuel, consumption and noise and vibrations. We will compare both diesel and gasoline engines and indicate their advantages and disadvantages at each of these points.



As far as price is concerned, the victory is clearly for the gasoline engine. Today, approximately a diesel engine is about twice as expensive as a gasoline. This is the difference of price appears when acquiring any machine or vehicle with diesel engine with respect to the price of one of gasoline.

This is mainly due to the following reasons:

  • More robust and heavy engines

Diesel engines are more robust and heavy because they have to withstand a greater effort. The thermodynamic cycle of the diesel engine is responsible for their overwhelming defeat, as they work with higher pressures and need a more consistent and therefore heavier engine.

  • Gas post-treatment system

Diesel engines have more complicated to pass the pollutant emission regulations because they generate more gases than their namesake to gasoline, therefore diesel engines are forced to introduce complicated particulate filters, SCR system (with urea) and EGR valve which Increase the final price of diesel engines.

The forthcoming anti-pollution regulations predict tougher measures even with diesel engines, so the price difference between diesel and gasoline engines will grow even more if the current trend continues.


This point in principle is the most controversial may cause, since it depends on many factors difficult to assess, but if we analyze two engines of similar characteristics in their diesel and gasoline version, working at 80% capacity in normal weather conditions, indicate which statistically speaking diesel engines have a longer duration than those of gasoline engines.

Obviously there are many factors that can influence this result, such as the use that is given to the engine installed in the generator, the time in operation, the maintenance that is performed, weather conditions, etc., these factors can decant the balance to one or the other engine.

On the other hand, diesel engines, when suffering a failure, have more sophisticated or complex components than gasoline engines (high pressure injection, large-scale turbochargers and more exhaust aftertreatment systems, etc.). Have much more serious failures and consequently much more expensive repairs than gasoline engines.

The maintenance cost of both engines, as far as labor is concerned, does not really exist a price difference. However as you can imagine the spare parts and consumables of diesel engines are usually much more expensive than those of gasoline.


With regard to fuel, we will differentiate between price and safety.

As for the price, gasoline is cheaper at the exit of refinery, but the taxes applied to this fuel, make the final price rises above diesel, making the latter much more economical for the end user.

Regarding safety, gasoline is more volatile, so that at room temperature it can ignite with some ease. However, diesel does not suffer from this problem.


At the moment the differences of consumption have been shortened to a great extent, but still we can clearly say without fear to mistake that in this section is the diesel engine is the clear winner with a lower consumption of fuel.

The main reason for this lower fuel consumption is that the thermodynamic cycle used by the diesel engine is higher performance (diesel cycle) compared to gasoline engines (Otto cycle). In addition, the throttle valve of the petrol engines introduces losses in the admission mainly at partial load.

Finally, diesel fuel has a higher energy density. That is, we are able in principle to get more energy per liter of fuel through the use of diesel (this means less consumption, no more power, not to be confused).


As already mentioned, diesel engines due to the thermodynamic cycle of the engine work at higher pressure, so they produce a higher vibration in the engine, which also normally this vibration is propagated to the chassis, which causes a much greater noise than Gasoline engines that are much quieter. However this difference is quite equal to raise the speed of work of both engines.

The noise and vibration factor both diesel and gasoline engines installed generators can be counteracted with the elements and suppression measures that were presented in the previous article, soundproof generators.


We can therefore conclude that it is convenient to install a gasoline engine in those generators in which its use is sporadic and / or punctual, with few hours of use per year. We will be much cheaper to purchase a generator with a gasoline engine and we will not affect in excess the greater amount of fuel price since it will hardly have operating hours a year and we will be more economical any repair of damage or maintenance.

While on the other hand it is advisable to install diesel engines in generators of prolonged or continuous use, since for a greater number of hours in operation, it will require a greater quantity of fuel, than thanks to the difference of price between the diesel and the price Of gasoline, the price increase of the generator set, spare parts and maintenance would be quickly amortized.

However indicate that many manufacturers of generators do not install gasoline engines in its range of generators with more power, and are usually made with diesel engines, as this type of equipment are often devote almost exclusively to prolonged or continuous use, as sources alternative or complementary energy.

Looking for a diesel or gasoline engine for a generator?

In Tecnics Grupos Electrógenos, S.L. We work with the main brands of the market and we have a wide range of motors, alternators, and spare parts for Generator Sets.

Call us and we will advise you!