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Design Innovation

MotoGP 2007: Criteria for Engine Optimization

[+] Author and Article Information
Enrico Mattarelli

DIMeC, University of Modena and Reggio E., Via Vignolese 905, 41100 Modena, Italymattarelli.enrico@unimore.it

J. Eng. Gas Turbines Power 130(1), 015001 (Jan 16, 2008) (10 pages) doi:10.1115/1.2771238 History: Received May 26, 2006; Revised May 11, 2007; Published January 16, 2008

The paper proposes some design criteria for the MotoGP engines, complying with the FIM 2007 Technical Regulations. Five configurations have been considered: engines with three cylinders in line and four cylinders in line, and three V engines with four, five, and six cylinders. All the analyzed solutions have been optimized from a fluid-dynamic point of view by means of one dimensional engine cycle simulations. Then, the engines are compared in terms of full load performance at steady conditions. Finally, the influence of engine performance, along with operation regularity and motorbike weight, is assessed by means of a lap time simulator, developed by the author on the base of real data. The best configurations turned out to be the four-cylinder engines, while three-cylinder and five-cylinder engines are quite penalizing. The key of the four-cylinder engines success is their good breathing capability and mechanical efficiency at high speed, yielding an optimum power-to-weight ratio, associated with a good engine regularity, i.e., a smooth response to throttle angle variations.

FIGURES IN THIS ARTICLE
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Copyright © 2008 by American Society of Mechanical Engineers
Topics: Engines , Stress , Cylinders , Valves
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References

Figures

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Figure 1

Percentage error on brake torque prediction at full load versus nondimensional engine speed

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Figure 2

Valve discharge coefficient, i.e., valve effective area divided by seat area at top engine speed, for three throttle positions (90deg, 50deg, and 20deg). The values calculated by CFD intake simulations are compared to their experimental steady counterparts.

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Figure 3

Valve discharge coefficient and pressure ratio across the valve at top engine speed for two throttle positions (90deg and 50deg). The steady discharge coefficient is also plotted as a reference.

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Figure 4

Flow field through the throttle body depicted on a cross section passing through the valve axis at 100deg after TDC (intake stroke), throttle angle of 50deg, and top engine speed. Results of a CFD-3D intake stroke simulation.

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Figure 5

Flow field through the throttle body depicted on a cross section passing through the valve axis at 120deg after TDC (intake stroke), throttle angle of 20deg, and top engine speed. Results of a CFD-3D intake stroke simulation.

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Figure 6

Experimental versus computational results of the reference engine (torque at partial load)

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Figure 7

Sketch of an intake manifold featuring telescopic trumpet

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Figure 8

Influence of the intake manifold Mach index on IMEP

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Figure 9

Influence of the intake taper Mach index on IMEP

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Figure 10

Influence of the exhaust primary pipe Mach index on IMEP

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Figure 11

(a) Comparison among the engines at WOT in terms of volumetric efficiency, residual fraction, and PMEP. (b) Comparison among the engines at WOT in terms of IMEP, FMEP, and BMEP.

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Figure 12

Comparison among the engines at WOT in terms of brake performance

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Figure 13

Throttle angle calculated by engine simulations at the exit of the Bucine turn

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