MClarenPower-Unit-honda

Foto di Racecar-Engineering

With a few clicks by Alberto Fabregas during the last Grand Prix we were able to understand more about the Honda engine. 
The design of the Japanese house seems very innovative in some respects, but the results of the last races you can see that it has not produced the desired results because of woeful unreliability.
 But we will try to make an analysis possible starting from these and other shots appearing over the weekend.

MClarenPower-Unit-honda5

Foto di Alberto Fabrega

From the photos immediately above we can see the intake duct which should lead to the air compressor in the’V’ of the engine that leads us to think that the same is located right between the two rows. The type should always be that of a centrifugal compressor although many experts have tried to assume an axial compressor. We feel this is not the case, since the axial compressor

MClarenPower-Unit-honda2

Foto di Racecar-Engineering

is characterized by a much lower compression ratio compared to the centrifugal compressor with all other things being equal, such as flow rate, inclination of the blades and speed of rotation.

To achieve a compression ratio equal to that of the centrifugal, the turbo would need more compression stages but those are technically prohibited by the Regulations. This area should be also where the MGU-H is mounted on an axis between the compressor and turbine but instead it is placed behind the engine. 
This solution involves a considerable savings of space in the engine compartment, and allowed the engineers to design a more powerful car under the streamlined appearance.
 The other side of the coin is certainly the adoption by Honda of a small compressor that would not guarantee a compression ratio necessary to obtain the power desired by the team. Another problem may be a very high temperature between the two rows that involve in addition to a higher mechanical stress also a lower yield of the compressor thus raising the temperature of the air that passes through it which would affect even in this case the power of the engine. The intercooler is used like air / air ducts which are visible in the photographs and should be gold and black in color which come from inside the V of the engine.

To conclude the discussion on the boost, we see the small size of the exhaust ducts such as Honda has decided to adopt. This solution was used by Mercedes last year but abandoned for 2015 because it brings with it a greater pressure in turbine, thus higher energy recovered, but the flow of exhaust gases is strongly penalized and requires a lot of the polishing on the car.

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Foto di Racecar-Engineering

Passando

Passing the aspiration can be noted the so-called ‘plenum’, or the area where the air intake is located. It is just before entering the combustion chamber and is made ​​of aluminum. This choice is also unconventional. Also the ducts of the entrance are rotated 90 degrees to reduce the height of the inlet and also improve in this case the design of the car. This should be equipped with intake trumpets of variable height used to improve the filling of the combustion chamber through the pressure waves that are created in that area at the opening of the valves.

MClarenPower-Unit-honda4

Foto di Racecar-Engineering

Turning to depart Electric Power Unit, according to Craig Scarborough, if the MGU-K has adopted a conventional arrangement below the left cylinder bank of the engine the same cannot be said for the batteries and the electrical module that control both the ‘MGU-H that the MGU-K. In fact appear to have been both merged into a single element positioned under the fuel tank.’

In conclusion, we can say that many of these decisions have been taken by some of the Honda engineers to try to have a car as powerful and aerodynamically efficient as possible. Unfortunately, as demonstrated by the results of these first GP this extreme design has created many problems of unreliability due in particular to the difficulty of cooling so many elements in relatively small spaces. The problems that have plagued both Button and Alonso from the beginning of the season have even led to the decision not to deploy Button’s car during the last GP.

However, we are of the opinion that the overall design of the car is technically very good and once solved, these teething problems of the Power Unit will lead to a competitive car. Maybe not directly in this year’s championship but McLaren-Honda’s car can perform much better.  They definitely will not be relegated to the last positions at the start and be able to fight for a podium finish and not just for points.

 

Dot. Ing.  Salvatore Di Nuzzo

Translation by  Christopher M. Uhl

 

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