What could cause these differences in torque, power and BSFC?

In summary, the conversation discussed engine testing at university using a JCB 4.4l twin turbo diesel engine. The results were compared to the manufacturer's graphs and showed a difference in torque, BSFC, and peak torque and torque band width. Possible causes for the difference were discussed, such as cold start, fuel and air temperature, flywheel, and equipment calibration errors. Further ideas were requested to investigate the issue.
  • #1
Webbd050
35
4
Ive been doing some engine testing at university and have created some torque, power ad BSFC curves. The engine used is a JCB 4.4l twin turbo diesel engine. I then compared to my results to the manufacturers graphs and got these. I need some ideas on what could cause the difference in torque, BSFC? What could cause the peak torque to be higher and the torque band narrower and the BSFC to be higher? I believe that the engine used in the uni test cell is a development version of the dieselmax and the one in the manufacturer specifications was the production model what could they have changed to cause the difference. Also the engine in the test cell is relatively green (not run in very much) which would surely mean the torque and BSFC would be lower which is contrary to the results. Maybe there is some calibration errors in the equipment? Some ideas that i could look into would be great if you have any. Thanks :)

Heres the graphs
http://imgur.com/a/yw1uJ
 
Engineering news on Phys.org
  • #2
Interesting graphs.
Probable possible causes that could happen:
-Cold start?
-Fuel temperature? Air temperature, pressure?
-Flywheel (is it the same?)
-What overall setup are you using? Engine+gearbox in neutral or bare engine?
 
  • #3
Lok said:
Interesting graphs.
Probable possible causes that could happen:
-Cold start?
No expert.
The torque spike in the mid-rev range means it could be cold start(also the fact that your bsfc is higher suggests cold start).So,the engine pumps in more fuel than air at the lower rev-range(more smoke hence).During cold start,the torque curve initially drops at the lower rev-range because of incomplete combustion(yellow flame). Once the engine hits a certain rev range,the torque curve should climb up back to the full load curve.But,your experimental graph is weird.It goes above the full load curve. Maybe your dyno has a defect??
 
  • #4
Would resonance in the intake/exhaust give that type of torque curve with a peak at which it is tuned?
No expert either.
 

1. What is torque and how is it related to power and BSFC?

Torque is a measure of the twisting force produced by an engine, which is typically measured in units of pound-feet (lb-ft) or Newton-meters (Nm). Power is the rate at which work is done, and is a function of torque and engine speed. BSFC (brake-specific fuel consumption) is a measure of the amount of fuel consumed per unit of power produced. These three parameters are interrelated and can affect each other depending on various factors.

2. What factors can cause differences in torque, power, and BSFC among engines?

There are several factors that can contribute to variations in torque, power, and BSFC among engines. These include engine design, fuel type, air intake system, exhaust system, ignition timing, and engine size. Other external factors such as altitude, temperature, and humidity can also impact these parameters.

3. How does engine design affect torque, power, and BSFC?

The design of an engine, including its number of cylinders, displacement, compression ratio, and valve configuration, can significantly impact torque, power, and BSFC. For example, an engine with a larger displacement or higher compression ratio may produce more torque and power, but may also have a higher BSFC due to increased fuel consumption. Similarly, an engine with a more efficient air intake and exhaust system may have better torque and power output, with lower BSFC.

4. Can fuel quality affect torque, power, and BSFC?

Yes, the type and quality of fuel used can have a significant impact on torque, power, and BSFC. Using a lower quality fuel with a lower octane rating can result in reduced performance and efficiency, as it may not be able to withstand high compression levels. Additionally, the presence of impurities or contaminants in the fuel can also affect engine performance and fuel consumption.

5. How do environmental conditions impact torque, power, and BSFC?

Environmental conditions, such as altitude, temperature, and humidity, can affect the performance of an engine and its associated parameters. In higher altitudes, where air density is lower, engines may produce less power and torque due to reduced oxygen levels. Similarly, cold weather can also impact performance, as colder air is denser and can improve combustion efficiency. Humidity can also affect engine performance, as the amount of water vapor in the air can impact the air-fuel mixture ratio and combustion process.

Similar threads

Specified Torque Specs on Automotive Fasteners -- Required or just suggestions?
    • Mechanical Engineering
Replies
10
Views
1K
Analytical mathematical modeling of the torque caused by the laundry
    • Mechanical Engineering
Replies
6
Views
1K
Is a Larger DC Motor Needed for Low Wind Speed Power Generation?
    • Mechanical Engineering
Replies
34
Views
2K
Plotting a Power Graph using Torque & RPM
    • Mechanical Engineering
Replies
3
Views
3K
How to Measure Torque Required for motor to spin a rotating shaft?
    • Mechanical Engineering
Replies
3
Views
2K
Can you help me calculate the required torque and power of this motor?
    • Mechanical Engineering
Replies
8
Views
1K
Torque and Rotational Power
    • Mechanical Engineering
Replies
4
Views
4K
Solving the Rewinding Tension Control Puzzle: A Production Engineer's Story
    • Mechanical Engineering
Replies
8
Views
2K
Automotive Electronic Torque Managment in an EV
    • Mechanical Engineering
Replies
7
Views
1K
Torque Reaction Force of Transmission and Drivetrain
    • Mechanical Engineering
Replies
10
Views
12K

Hot Threads

Recent Insights

Back
Top