Yamaha queen of MotoGP: how Quartararo’s in-line 4-cylinder works

Less powerful than the Ducati V4 engine, but very balanced in power delivery. Having solved the problems of grip and high temperatures, the Frenchman made the most of the flexibility and versatility of the Yamaha engine

Massimo Falcioni

Hats off to Fabio Quartararo for the MotoGP title won with two races in advance at the age of 22 and honors to Yamaha which, despite not being given at the beginning of the season as bike No. 1, managed to beat the large and qualified competition thanks to quality of its driver and of an M1 that has its strengths in its driveability and general technical balance.

i meriti yamaha

In this case, the merits should not be divided “fify-fifty” between rider and bike, because the difference was made on the Quartararo track, this season a notch above the other riders of the house of the three forks and not just for five victories and the five podiums but also, or above all, because he contributed to creating the conditions of unity and motivation in the team, with a healthy enthusiasm, indispensable for great results. However, credit must be given to Yamaha and first of all to his team for having focused on the winning horse and also for having always believed in the goodness of their engine, the 4-cylinder in-line, considered by many to be outdated, to be put in the attic. The beginnings of the 2021 season, with Yamaha’s first three victories in Viñales (Losail 1) and Quartararo (Losail 2 and Portimao), had made it clear that the air was pulling while noting that Iwata’s bikes were certainly not the fastest. This was also confirmed in the last race of Misano2 where the fastest bike was Zarco’s Ducati (305 km / h) ahead of Viñales’ Aprilia (304.2) followed by Bastianini’s Ducati (302.5), Martin ( 302.5), Marini (301.6). The winner Marquez is only 13th (299.1) with Quartararo behind (before Yamaha 298.3). Bagnaia is fifth from bottom (297.5) followed by the two Yamahas of Rossi (295.9) and Morbidelli (295), then Petrucci (294.2), last is Dovizioso’s Yamaha (293.4). Eleven km / h difference in speed between the first and the last is an abyss, especially on a circuit like Misano. The reasons for these differences are many but undoubtedly there is also a question of power where Yamaha is certainly not at the top.

horse question

The power of the engine is needed but that’s not all because the decisive factor is how this power is delivered, how it translates into the tires, how it is managed by the rider in each circuit to optimize driveability, to give more aerodynamic load on the front wheel, improving the insertion in cornering and reduce wheelies under acceleration which increase the lap time. This, for example, was the limit of Marquez’s Honda in the Misano race on Sunday, especially at the exit of Tramonto but also of the Carro, unlike the Ducati of Bagnaia and the Yamaha of Quartararo. On a technical level, the world title conquered by Quartararo on the Yamaha raises the question again: better the V4 engine or the 4 in line? With current regulations of the MotoGP particularly restrictive (1000 cc displacement, maximum 4-cylinder fractionation, with 81 mm bore, single electronic control unit, etc.) each of the two constructive philosophies has advantages and disadvantages.

motogp engines in comparison

The Yamaha M1 has a great frame and excellent driveability but, as mentioned, it suffers in power, acceleration and speed. There was, particularly pressing until last season, the problem of grip on the track: that is, the lack of grip, especially in some asphalt conditions (slippery) and weather conditions (high temperatures) with less grip, losing in braking and above all in acceleration. In particular, it was Rossi who complained, practically every race weekend. The previous electronics gap was brilliantly bridged by Yamaha. The real problem concerned the technical and technological basis of the entire project of the “four in line” engine, in particular the crankshaft redesigned several times. Unlike Formula 1, in MotoGP the right compromise of the crankshaft inertia value is a very important factor as the footprint of the rear tire is reduced and consequently, too fast acceleration variations generate an abrupt delivery of the rear tire. couple. A low inertia crankshaft provides higher acceleration than a higher inertia one. But with this configuration, for the motorists and for the electronics, it is more complicated to manage the torque and calibrate the electronics, to the variable conditions of the track and of the different tire compounds. It is for this reason that a crankshaft with higher inertia ensures a more manageable power delivery, especially at small throttle openings. The problem is evident mainly in corners, when the rider reaches the maximum inclination, with a small opening of the throttle. In this situation the power required from the engine is less and, due to the low air speeds in the intake ducts, the mixing in the combustion chamber is not homogeneous with a high cyclic dispersion and irregular ignitions. driver has to manage a not very linear motor torque, often very abrupt.

the mechanisms of motogp

To deal with these problems, the electronics can intervene on the “traction control” strategies, turning on only some of the cylinders. If, however, the shaft inertia is too low, even the electronic interventions are not sufficient to solve the problem. Of course, opening the throttle with a linear connection of the engine torque, reduces the stress on the rear tire, prevents skidding and facilitates the setting of the frame. In short, complex technical and technological issues: it is not simply a question of V-shaped or in-line cylinders. The Yamaha 4-cylinder in-line engine (same as the Suzuki one) is not technically outdated. It is not just a question of the engine. If the V4 has a reduced rate of friction losses with a more compact crankshaft, therefore an engine with an excellent balance between maximum power and torque and chassis with less transverse dimensions of the bike, development of aerodynamics, in general excellent driveability, the 4 in line it offers large margins of intervention in the rear suspension geometries (swingarm pivot far forward, etc.) with positive effects on grip and the possibility for the rider to optimize the electronic power to the fullest. With those restrictive regulatory limits mentioned above, the V4 is as if “caged” in its power potential and rpm allowing the “older” 4 in line to be competitive.

more power or balance?

Today, what pays in MotoGP is not the revolutionary project to have more laps and therefore more power but the balance of all the components, with great commitment to the development of aerodynamics, which allows the bike to ground all its power. and allows the rider the maximum feeling and the possibility to express their full potential as a “handle”. It is this great work done by Yamaha in particular step by step, swallowing not a few toads, which in the end led to the result, to the world title. Fabio Quartararo, his talent and his tireless refinement work, deserve the great credit for having been able to interpret and manage this potential in the best possible way on the track.

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Yamaha queen of MotoGP: how Quartararo’s in-line 4-cylinder works

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