Sunday, January 19, 2014
How to Calculate Engine Power in the Metric System
Nearly every car commercial boasts about the car engines horsepower. But for people outside the U.S., or with a scientific background but not a car background, it may be unclear how much power a horsepower truly is. One horsepower is defined as 33,000 lb*ft/min (pounds times feet divided by minutes). So, converting horsepower into the metric system is simply a matter of converting the separate units of force, distance and time to arrive at a value in Nm/s (Newtons times meters divided by seconds), also known as Watts.
Instructions
- 1
Convert pounds to Newtons using the conversion factor 4.448 N/lb. If we take the original figure of 33,000 lb*ft/min and multiply by 4.448 N/lb, we get 146,784 N*ft/min.
2Convert feet to meters using the conversion factor 0.3048 m/ft. If we multiply this by 146,784 N*ft/min (our figure from step 1), we get 44,740 N*m/min.
3Convert minutes to seconds using the obvious conversion factor 60 s/min. Because minutes is in the denominator of our figure, we must divide the figure by this conversion factor to get the minutes to cancel out. 44,740 N*m/min divided by 60 s/min yields 745.7 N*m/s, or 745.7 W.
4Calculate the metric power of an engine from its horsepower rating using this figure. Since we know that 1 horsepower = 745.7 W, we can simply multiply the horsepower of an engine by 745.7 to arrive at a value in Watts. For example, a 300 horsepower engine puts out 300 * 745.7 = 223,700 W, or 223.7 kW.
Monday, November 11, 2013
How to Calculate an Exhaust Header
No matter the exhaust header length in a car, the choice of a length matches the specific needs of the car. While short lengths, for example, are easier to install, long lengths are more difficult to install but best for high performance. If you know the Engine Cubic Inch Displacement, the Engine Maximum Revolutions Per Minute, and the Header Tube Outside Diameter , you can use the Bowlings Best Exhaust Header Predictor equation to determine the best exhaust header tube length for your car engine.
Instructions
- 1
Define the parameters you will need. The equation you will use states that Exhaust Header Length (H) in inches equals Engine Cubic Inch Displacement (CID) in inches times 1900 divide by Engine Maximum Revolutions Per Minute (RPM) in revolutions per minute divide by Header Tube Outside Diameter (OD) in inches. Therefore, you will need three parameters: "CID", "RPM", and "OD".
2Simplify the calculation. Calculate "CID" times 1900 with the aid of a calculator to obtain a single value, which we will call the numerator. Calculate "RPM" times "OD" with the aid of a calculator to obtain a single value, which we will call the denominator.
3Perform the calculation. Calculate the numerator divide by the denominator with the aid of a calculator to obtain "H".
