Comparison of two engines of the same displacement

In summary, the conversation is discussing two engines with the same displacement but different piston sizes. One person suggests that the smaller piston with a longer stroke may have higher low-end torque, making it the "stronger" engine. However, another person adds that a shorter stroke can cause issues with valve clearance and high performance engines tend to favor an equal bore and stroke for a more balanced design.
  • #1
anhtho
9
0
Hi all,

I have this question, and hope you could help me to solve.

There are two engines with the same displacement (say 250cc). One with smaller piston and the other bigger. Of course the first one will move longer.
If everything else is the same or similar, generally, which engine is the stronger ?

Thanks for any input.
 
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  • #2
With a larger piston you can have crank/ rod geometry which favors higher rpm (because the piston acceleration is lower). Which means you can get more power.

I believe the longer stroke of the smaller piston favors higher low-end torque, which makes this the "stronger" engine (stronger, but less powerful).

I'm sure there is more to it than that, so someone else please chime in...
 
  • #3
With a short stroke a problem arises with clearance for the valves makers of high performance engines tend to favour an equal bore and stroke a so called square design
 

1. What is the difference between two engines of the same displacement?

The main difference between two engines of the same displacement is their design and construction. This includes the number of cylinders, the arrangement of cylinders, the type of fuel injection, and the use of forced induction. These differences can affect the power output, fuel efficiency, and overall performance of the engines.

2. How do I know which engine is better?

The quality of an engine cannot be determined solely by its displacement. Other factors such as horsepower, torque, and specific output should also be considered. It is important to examine the specifications and performance of each engine to determine which one is better suited for your needs.

3. Can two engines of the same displacement have different power outputs?

Yes, two engines of the same displacement can have different power outputs. This is because there are various factors that can affect the power output of an engine, such as the design, fuel type, and tuning. Even small differences in these factors can result in significant variations in power output.

4. Are there any advantages of having two engines with the same displacement?

Having two engines with the same displacement can provide consistency in performance and maintenance. This is especially useful in industries where uniformity and reliability are important, such as in aviation or marine applications. Additionally, having two engines of the same displacement can make it easier to find and replace parts.

5. What are some potential drawbacks of two engines with the same displacement?

One potential drawback of two engines with the same displacement is that they may have similar power outputs, making it difficult to achieve significant performance gains. This can be a disadvantage in industries where high power output is necessary. Additionally, having two engines of the same displacement can also make the vehicle or equipment heavier, resulting in reduced fuel efficiency and higher operating costs.

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