Engine Preheater


Carlor Engineering is a Belgian company that specialises in manufacturing electric coolant preheating systems for use with all types of heat engines. Carlor is your trusted partner in the field of engine block heaters, electric heaters and much more.
Our products are designed to be installed in heat engines for generator sets, locomotive engines, construction and emergency vehicles, lorries, buses and even marine engines.
Engine heater advantages

Carlor recently ordered two studies from Liège University on the impact of a Carlor engine heater system on emissions of toxic substances and the general consumption of an engine. The results were impressive, a return on investment can be achieved for the acquisition of a Carlor preheater in just one year.

Study no. 1: Reducing emissions for toxic substances

The study was carried out on a direct injection diesel engine (1896 cm³, 66 KW at 4,000 rpm).

Three journeys were considered: 3.2 km, 15 km and 34 km with an ambient temperature of +25°C.


Pollution and total consumption weighted without a engine heater with an outdoor temperature of 25°C.

  CO emissions (g/km) HC emissions (g/km) Consumption (litres/100 km)
For 3.2 km
For 15 km
For 34 km


Pollution and total consumption weighted with a Carlor engine heater at an engine temperature of 50 °C.

  CO emissions (g/km) HC emissions (g/km) Consumption (litres/100 km)
For 3.2 km
For 15 km
For 34 km


Gains thanks to preheating the engine to 50°C using the Carlor engine heater

  HC emissions (%) CO emissions  (%) Consumption (%)
For 3.2 km
For 15 km
For 34 km

For HC and CO: Pollution during the initial seconds represents the main share of thepollution emitted during the journey. This share is particularly high for start-ups at low temperatures. The pollution emitted during the journey is not proportional to the length of the journey, as the weighting of the initial seconds is decisive.

The decrease in pollution levels over the initial kilometres was impressive: 45.04% for HC and 16.12% for CO!

It is important to remember that the study was carried out at an outdoor temperature of +25°C, while the mean temperature in Belgium is +10°C… There can be no doubt that in most cases, the decrease in pollution levels achieved thanks to the Carlor preheater will be far higher than the above figures.


Study no. 2: Reducing consumption

The results of the following tests were achieved on a direct injection diesel truck engine, with the following characteristics:

  • Cubic displacement: 8455.7 cm3
  • Volume of water: 25.55 litres.
  • Volume of oil: 20.820 litres.
  • Mean power: 103 Hp.Mean consumption: 17 litres / hour (running at idle, with no loads)
1. Fuel savings at start-up

Fuel savings can be estimated as follows based on the results for the engine:

Carlor engine heater warming the engine to 30°C above outdoor temperature.
Fuel savings when starting-up at –20°C 1.97 litres 11.58%
Fuel savings when starting-up at –15°C 1.78 litres 10.47%
Fuel savings when starting-up at –10°C 1.63 litres 9.59%
Fuel savings when starting-up at –5°C 1.49 litres 8.76%
Fuel savings when starting-up at 0°C 1.37 litres 8.05%
Fuel savings when starting-up at +5°C 1.27 litres 7.47%
Fuel savings when starting-up at +10°C 1.19 litres 7.00%
Fuel savings when starting-up at +15°C 1.11 litres 6.52%


2. Reduction in consumption due to the rise in temperature of the diesel with the Carlor engine heater

The improved performance indicated below was calculated by extrapolating between the temperatures of -10°C and + 60°C based on linear regression. This reflects the reality in an optimised manner.

Fuel savings based on the increase in diesel temperature.

Fuel consumption will decrease as fuel temperature increases. Therefore, with a mean annual temperature in Belgium of 10°C, if we increase the temperature of the diesel by 40°C, fuel consumption will decrease by 1.24% when compared with mean consumption levels for the engine.

These tests provided us with ballpark figures for savings. Let us consider the example of a truck driving for 8 hours per day over 200 days each year, with a mean outdoor temperature of + 10°C. The following savings would be achieved in this case:

1. At start-up:

By heating the engine to 30°C above outdoor temperature:

17 litres x 7% x 200 days = 238 litres of diesel per year.

2. When driving:

If the temperature of the diesel is increased by 40°C:

17 l. x 1.24% x 200 days x 8 h. / 100 = 337 litres of diesel per year.

i.e. an overall annual saving of 575 litres of diesel.

i.e. an overall saving of 2875 litres of diesel over five years!

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