Lesee if this works
05-26-2004, 12:29 PM
#1
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Lesee if this works
I can't seem to grasp the concept of a 4 valve per cylinder engine. I understand INTAKE, COMPRESSION, COMBUSTION, and EXHAUST, but for a 2 valve.
***can't make the shockwave flash work!***
Taken from http://auto.howstuffworks.com/engine4.htm
Any help?
http://static.howstuffworks.com/flash/engine.swf
***can't make the shockwave flash work!***
Taken from http://auto.howstuffworks.com/engine4.htm
Any help?
http://static.howstuffworks.com/flash/engine.swf
Last edited by gpatmac; 05-26-2004 at 12:35 PM.
05-26-2004, 12:37 PM
#2
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from howstuffworks.com
Having four valves per cylinder gives an engine several advantages.
By having four valves in a cylinder instead of two, a larger portion of the area can be used to let air in and exhaust out. The engine can make more power if more air enters the cylinder, and it wastes less power if it is easier to pump the exhaust out of the cylinder.
At higher engine speeds, the engine pumps a lot of air though the cylinders. Having four valves per cylinder allows the engine to pump enough air to run and make useful power at these higher speeds.
Another interesting thing that some car makers do is have a separate intake runner for each of the two intake cylinders. One of the intake runners is wide and short for maximum airflow, the other is a tuned intake runner.
When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.
If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.
Having four valves per cylinder gives an engine several advantages.
By having four valves in a cylinder instead of two, a larger portion of the area can be used to let air in and exhaust out. The engine can make more power if more air enters the cylinder, and it wastes less power if it is easier to pump the exhaust out of the cylinder.
At higher engine speeds, the engine pumps a lot of air though the cylinders. Having four valves per cylinder allows the engine to pump enough air to run and make useful power at these higher speeds.
Another interesting thing that some car makers do is have a separate intake runner for each of the two intake cylinders. One of the intake runners is wide and short for maximum airflow, the other is a tuned intake runner.
When the intake valve is open on the engine, air is being sucked into the engine, so the air in the intake runner is moving rapidly toward the cylinder. When the intake valve closes suddenly, this air slams to a stop and stacks up on itself, forming an area of high pressure. This high-pressure wave makes its way up the intake runner away from the cylinder. When it reaches the end of the intake runner, where the runner connects to the intake manifold, the pressure wave bounces back down the intake runner.
If the intake runner is just the right length, that pressure wave will arrive back at the intake valve just as it opens for the next cycle. This extra pressure helps cram more air-fuel mix into the cylinder -- effectively acting like a turbocharger.
Still input is welcome.
05-27-2004, 01:15 PM
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Are 2 of the valves intake and 2 exhaust? If so, do both intake valves open at the same time and same same for exhaust?
Is the WRX intake runners as described in the 2nd paragraph that I quoted?
Is the WRX intake runners as described in the 2nd paragraph that I quoted?
05-27-2004, 02:22 PM
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Yes (2 and 2). Each set of valves opens simultaneously with it's partner. Intake runner tuning isn't as important in a forced induction engine because volumetric efficiency is already over 100% by definition when in boost.
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05-27-2004, 02:46 PM
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Anytime my Brohem.
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