Everyday Examples in Engineering - Dynamics
August 2014
 

The purpose of this project was to make a comprehensive assignment that is real and interesting to engineering and technology students. Many assignments in a dynamics course are strictly academic in nature, not attracting the students’ interest and often leaving the students wondering about the application.

Most engineering and technology students have at least a cursory interest in drag racing and some may be full-fledged enthusiasts or participants. Consequently, this assignment should have broad appeal in a dynamics course.

Students are given measured engine performance data for a Chevrolet Corvette C6-05. They are given the approximate values for the weight of the car, its transmission shift schedule, its differential ratio, its tire diameter, and a common method for estimating both rolling resistance and wind resistance. Students are also given the actual drag racing results published for a 1999 Chevrolet Corvette Coupe. It is not known if the weight, transmission, differential, and tire data given to the students matches that of the car for which race data is published but they are assumed to be close enough for the purpose of this assignment.

The assignment is comprehensive in that it requires utilizing the relationship of power to force and acceleration in free-body and kinetic diagrams, requires modeling of dynamic resistive forces, and requires finding displacement and time associated with non-constant acceleration. The five race data that are published include 1/4 Mile ET (elapsed time), 1/4 Mile MPH (miles per hour), 1/8 Mile ET, 1/8 Mile MPH, and 0-60 Foot ET. By carefully establishing a spreadsheet to carry out the appropriate integrations, students should able to closely match all five race data.


The full report is free to download for non-commercial purposes.

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To address why powertrain performance should be measured, Rototest Research Institute has published an article where powertrain performance measurements versus engine performance is discussed. The article also includes statistical data where stated engine performance is compared to powertrain performance. [ More... ]

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From James Watt and the steam engine to performance measurements in the racing industry; this series of three articles deals with all the questions that are essential when conducting powertrain performance measurements. This particular issue contains the history and fundamental physics of powertrain performance measurements. [ More... ]

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What is repeatability? And what is accuracy? How do they correlate? The second part in the series of articles on performance measurements will answer these questions. It will also describe how measurement chains and tolerances will affect the accuracy of your test equipment. [ More... ]

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This is the final part of the series. Matters such as advantages and disadvantages in test methods will be discussed, and also how test results are analyzed and presented. [ More... ]

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In this article Marco Alsterfalk of the Swedish tuning company www.MTE.se explains issues such as the fuel enrichment effect on high load operating points, definition of knock, the fundamentals of knock, what the optimum lambda is and how the knock limit and indicated mean effective pressure (imep) are affected by variations in lambda. [ More... ]

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In-Depth Race Car Performance Analysis
June 2009
 

A Porsche 911 GT3 Cup race car has undergone a world unique performance analysis to show its competitiveness in the global Carrera Cup series. Information that every race car driver must know.


Report Summary:

A Powertrain Performance Assessment, PPA, has been made on a Porsche 911 GT3 on behalf of Flash Engineering. The car is a 2009 model and recently delivered from Porsche. Tests were performed at 30 March 2009 on a ROTOTEST VPA-RX8 2WD chassis dynamometer which is of a hub-connected type. Compared to an engine dynamometer the engine performance is reduced with drivetrain losses. It is of course important to have a powerful engine but from the drivers' point of view, it is the power available to the wheels that the driver can make use of.

All tests have been run in 5th gear and started with a Steady State test at every 500 rpm beginning from 2000 rpm. Maximum performance numbers are 386.4 Nm of torque and 410.2 PS of power. Compared to the stated factory numbers of 410 Nm and 420 PS there is a difference of 5.8% and 2.3% respectively. The torque difference is in the expected range whereas the power difference indicates slightly more engine power than stated.

The car has also been subjected to tests at Steady Rate. This means measurements during controlled accelerations. 4 rates have been tested; 300, 500, 700 and 1000 rpm/s. During accelerations some of the engine power is used solely to accelerate the inertia of the powertrain. This loss is increasing with the rate of acceleration. An estimation of the Powertrain Inertia shows a value of 0.16 kgm2 which equals having an extra weight of 222 kg in 1st gear. The actual value of Powertrain Inertia is relatively low considering the size of the engine.

Compensating for the estimated inertia show that the engine is producing approximately 10 Nm and 5 PS more during acceleration compared to Steady State. This may be related to less tendency to knock during acceleration. In any case it clearly shows a performance potential that would have been missed if the mapping had only included static conditions. Especially for a race car the improvements can be considered to be large. From the drivers standpoint it can very well be the difference between winning or loosing.


Driver

H.R.H. Prince Carl Philip Bernadotte
More info at:
www.royalcourt.se
www.carreracup.se


The full report Powertrain Performance Assessment, PPA, Porsche GT3 Cup 2009 is free to download for non-commercial purposes.

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Tuning theory, Part 5
January 2009
 

This is the fifth and last feature article in an feature article series about tuning a VW Passat 1.8 turbo. The unique educational feature article series, with its 30 000 EUR budget, was made possible through a cooperation between Rototest Research Institute and the Swedish auto magazine Bilsport.

Rototest Research Institute whishes to thank Bilsport (www.bilsport.se) with staff for its capable cooperation for more car tuning knowledge.

Passing examination in the family car tuning school
Includes: Power or torque, constant speed, change gear at crossing, power accelerates, tops 245, fit or slack, changes character, change gear whenever and optimal gear ratio.

Graphs: Tractive effort, acceleration improvement, Powertrain Performance Toyota Corolla and VW Golf GTI, acceleration potential Toyota Corolla and VW Golf GTI.

Reader questions and comments:
Please write to tuning-theory@rri.se, open to december 2009.

The article is free to download for non-commercial purposes.

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Tuning theory, Part 4
January 2009
 

This is the fourth feature article out of a total five in an feature article series about tuning a VW Passat 1.8 turbo. The unique educational feature article series, with its 30 000 EUR budget, was made possible through a cooperation between Rototest Research Institute and the Swedish auto magazine Bilsport.

Rototest Research Institute whishes to thank Bilsport (www.bilsport.se) with staff for its capable cooperation for more car tuning knowledge.

Mapping - the final touch
Includes: Tough adjustments, original system preferred, difficult torque curve, retain the margins, volumetric efficiency, knocking, the three elements of combustion, lambda value and 200 with environmental conscience.

Graphs: Mass flow and Diff temp, cooling efficiency, cooling power, engine speed and temp. after turbine, pressure loss exhaust with and without catalyst, powertrain performance, wheel torque and inlet pressure standard, with new exhaust, with new intercooler, and with a new engine calibration, engine speed and injector duty cycle, throttle, lambda, inlet pressure, engine speed and volumetric efficiency relative total, lambda.

Reader questions and comments:
Please write to tuning-theory@rri.se, open to december 2009.

The article is free to download for non-commercial purposes.

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Tuning theory, Part 3
September 2008
 

This is the third feature article out of a total five in an feature article series about tuning a VW Passat 1.8 turbo. The unique educational feature article series, with its 30 000 EUR budget, was made possible through a cooperation between Rototest Research Institute and the Swedish auto magazine Bilsport.

Rototest Research Institute whishes to thank Bilsport (www.bilsport.se) with staff for its capable cooperation for more car tuning knowledge.

The intercooler´s to be - or not to be?
Includes: Higher density, efficiency increases with the flow, theory can be destroyed, standard elements, perceived as gain, double cooling capacity, chassis dynamometer - that´s how it works, a tolerance of one percent, different measuring methods, forget the 25 percent losses and counting the horses.

Graphs: Pressure drop over the intercooler, powertrain performance with standard and new exhaust system and with new intercooler, air mass flow and pressure drop, air mass flow and cooling power and diff temperature and cooling efficiency.

Reader questions and comments:
Please write to tuning-theory@rri.se, open to december 2009.

The article is free to download for non-commercial purposes.

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Tuning theory, Part 2
August 2008
 

This is the second feature article out of a total five in an feature article series about tuning a VW Passat 1.8 turbo. The unique educational feature article series, with its 30 000 EUR budget, was made possible through a cooperation between Rototest Research Institute and the Swedish auto magazine Bilsport.

Rototest Research Institute whishes to thank Bilsport (www.bilsport.se) with staff for its capable cooperation for more car tuning knowledge.

Big exhaust system - benefit or pleasure?
Includes: Disadvantage or advantage, pre-condition for more power, half the gain, the surge line, measurements and results, more air in, specific fuel consumption, conclusions, volumetric efficiency, total volumetric efficiency and counting of molecules.

Graphs: Performance during an acceleration at 500 rpm/s, power and torque with new exhaust, exhaust performance, breathing capacity and efficient use of fuel and air.

Reader questions and comments:
Please write to tuning-theory@rri.se, open to december 2009.

The article is free to download for non-commercial purposes.

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Tuning theory, Part 1
August 2008
 

This is the first feature article out of a total five in a feature article series about tuning a VW Passat 1.8 turbo. The unique educational feature article series, with its 30 000 EUR budget, was made possible through a cooperation between Rototest Research Institute and the Swedish auto magazine Bilsport.

Rototest Research Institute whishes to thank Bilsport (www.bilsport.se) with staff for its capable cooperation for more car tuning knowledge.

Family car tuning under the magnifying glass at Rototest Research Institute
Includes: Background, test object, steady state and sweep, theoretical interpretations, measurements and results, turbo life and pressure, injector limit, exhaust temperatures, low exhaust noise-back pressure, still clean at 190 km/h and the compressor map.

Graphs: Power and torque - the original, information at max performance, intercooler performance, exhaust performance, speed related performance and the compressor map.

Reader questions and comments:
Please write to tuning-theory@rri.se, open to december 2009.

The article is free to download for non-commercial purposes.

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