Can a 1.3 hp Engine Power Our Prototype Car?

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SUMMARY

The discussion centers on determining whether a 1.3 hp, 35cc single-cylinder air-cooled 4-stroke OHV engine can power a prototype three-wheeled car weighing 120 kg. Key calculations reveal total power losses of 1.234 hp, factoring in road gradient, rolling resistance, and drag. To ensure optimal performance, it is crucial to account for drivetrain friction and conversion losses. The overall efficiency of the powertrain must also be considered, with a suggested calculation method provided for determining required engine power based on efficiency losses.

PREREQUISITES
  • Understanding of power loss calculations in automotive engineering
  • Familiarity with drivetrain efficiency metrics
  • Knowledge of vehicle dynamics, including rolling resistance and drag coefficients
  • Basic principles of thermodynamics as applied to engine performance
NEXT STEPS
  • Research methods for calculating drivetrain power losses in automotive applications
  • Learn about the impact of rolling resistance coefficients on vehicle performance
  • Explore the principles of engine efficiency and optimal operating conditions
  • Investigate the effects of different gear sets on overall powertrain efficiency
USEFUL FOR

Engineers, automotive designers, and hobbyists involved in prototype vehicle development and performance optimization will benefit from this discussion.

Carvinos
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Hello!
Actually i want to find the required power of an a single cylinder air cooled 4 stroke OHV engine. i have calculated three power losses, power loss against road gradient (Pg), rolling resistance (Pr) and drag (Pd) using the following formulae:
Pg=M*g*v*grad=1.095 hp
M(mass of the prototype car)=120kg, g=9.8 m/s^2, v(prototype car velocity)=13.88 m/s, road gradient= 5% (0.05)
Pr=RRC*M*g*v=0.109 hp
RRC (rolling resistance coefficient)=0.005 for a bicycle tire we are using in our prototype car
Pd=0.5*rho*v^3*Cd*A = 0.030 hp
rho=1.099 kg/m^3, Cd (Coefficient of drag)=0.04 in case of our prototype car, A=0.384 m^2
Net power losses=Pg+Pr+Pd=1.234 hp.
Now please tell me can i use an engine of 1.3 hp of 35cc volumetric capacity in our prototype three wheeled car. Generator is the only accessory that will be connected with the engine to charge the battery.13.88 m/s will be the max. speed of our prototype car, 120 kg is the mass of the prototype with driver. reply soon please
 
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Did you calculate the rolling resistance for all wheels?
Have you applied a safety factor, and an allowance for acceleration (and not just travel at a constant speed)?
Have you considered friction in your drivetrain?
Have you considered conversion losses through the powertrain (including your 'generator'?)
Is your engine going to be operating at optimum conditions for 1.3hp?
 
ok.thnx.tell me please the procedure of how to calculate the power losses of engine through transmission.
 
Carvinos said:
ok.thnx.tell me please the procedure of how to calculate the power losses of engine through transmission.

For every gear set or belt drive set, assume 95% efficiency. For every chain drive set, assume 92% efficiency. Multiply all of them for overall efficiency.

Ex.:

if the power of your engine goes through 3 gear sets before reaching the wheels, your overall efficiency would be 0.95*0.95*0.95 = 0.857. So if you need 1.234 hp at the wheel, you need 1.234 / 0.857 = 1.44 hp at the engine.
 

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