# Finding out the time duration for which intake valve remains open

• monty37
In summary, the conversation revolved around calculating the time it takes for a 4-cylinder diesel engine to complete one cycle and determining the duration of the intake valve being open. It was discussed that this information is dependent on the camshaft specifications and that measuring it in a running engine would be difficult. It was suggested to obtain the cam profile and use kinematics to predict the valve open time.
monty37
I set out to find out how many seconds it takes for a 4cylinder naturally aspirated diesel engine to complete 1 cycle(4 strokes):
I considered a tata indica model
max power:53.5PS@5000rpm

therefore 5000 rev per min or 83.3 rev per sec
now it takes 0.012 seconds to complete 4 strokes or 1 cycle and 6x10^-3 seconds for 2 strokes

Now I want to find how much time does the intake valve remain open.

That is impossible to know without knowing the exact camshaft specs.

you mean to say the crank angles at which the valves operate ..now if i know the time
duration for the intake stroke can i not find out the valve open duration..in seconds?

About 0.006 seconds, assuming 180 open duration out of the 720 degrees needed to complete one cycle (0.024 sec., not 0.012).

It sounds like you're assuming that the intake opens exactly at TDC and closes at BDC; not so. As mentioned, the intake opening and closing points will depend on the design specs of the camshaft.

The whole point is racing cam design is to get maximum open time while still getting the valve securely seated in time to prevent blow back when ignition begins. Lots of effort goes into cam design, and as a result, the performance with each cam will be different. Measuring this in a running engine is going to be extremely difficult. You would be much better off to get the cam profile and then work through the kinematics of the valve gear in order to predict the valve open time.

## 1. How is the time duration for intake valve opening calculated?

The time duration for intake valve opening is typically calculated by measuring the opening and closing times for the valve using a timing light or oscilloscope. The duration is then calculated by subtracting the closing time from the opening time.

## 2. What factors can affect the time duration for intake valve opening?

The time duration for intake valve opening can be affected by several factors such as engine speed, valve size, camshaft profile, and engine temperature. These factors can impact the amount of time the valve remains open, and therefore, the overall performance of the engine.

## 3. How does the time duration for intake valve opening impact engine performance?

The time duration for intake valve opening plays a crucial role in engine performance as it determines the amount of air and fuel that can enter the combustion chamber. A longer duration can increase the engine's power and torque, while a shorter duration can improve fuel efficiency.

## 4. What is the ideal time duration for intake valve opening?

The ideal time duration for intake valve opening can vary depending on the engine's specifications and intended use. Generally, for street applications, a duration between 200-220 degrees is considered optimal, while for racing applications, a longer duration may be necessary for maximum power output.

## 5. How can the time duration for intake valve opening be adjusted?

The time duration for intake valve opening can be adjusted by changing the camshaft profile or installing a performance camshaft with a different duration. The valve timing can also be altered by advancing or retarding the camshaft using a timing gear or belt. It is essential to consult a professional mechanic or engine tuner before making any adjustments to ensure proper engine performance.

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