Gases increase volume in combustion. There will be more CFM out than CFM in at a given RPM. Why are intake valves bigger than exaust valves?
Why are intake valves bigger than exhaust valves?
- Thread starter Jonny Z
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Because it's more important to get more fuel/air in the engine. That is why in 3V engines there are 2 intake and 1 exhaust. It is easier to push gasses out of the cylinder than to pull them in.
You have maximum of a 14.7 psi pressure differential pushing air through the intake. You have lot more pressure pushing the exhaust out so they use more of the available area for the intake valve.
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
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lolz
Originally Posted By: XS650
You have maximum of a 14.7 psi pressure differential pushing air through the intake. You have lot more pressure pushing the exhaust out so they use more of the available area for the intake valve.
I will buy that.
You have maximum of a 14.7 psi pressure differential pushing air through the intake. You have lot more pressure pushing the exhaust out so they use more of the available area for the intake valve.
I will buy that.
Originally Posted By: rudolphna
It is easier to push gasses out of the cylinder than to pull them in.
Yes ... in a normally aspirated engine, you have less than 15 psi (1 atmosphere of pressure) pushing air into the cylinder through the intake valves. If the intake valves were small, they would restrict the flow and cause the volumetric efficiency to decrease.
It is easier to push gasses out of the cylinder than to pull them in.
Yes ... in a normally aspirated engine, you have less than 15 psi (1 atmosphere of pressure) pushing air into the cylinder through the intake valves. If the intake valves were small, they would restrict the flow and cause the volumetric efficiency to decrease.
The exhaust gas is hot, and therefore less dense. That is also why exhaust valves are made smaller.
Originally Posted By: artificialist
The exhaust gas is hot, and therefore less dense. That is also why exhaust valves are made smaller.
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That has nothing to do with why the E valve is smaller. It has already been said but I'll say it again, it is much easier for the cylinder to PUSH the expanding exhaust gases out than it is for it to SUCK the intake in.
The exhaust gas is hot, and therefore less dense. That is also why exhaust valves are made smaller.
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That has nothing to do with why the E valve is smaller. It has already been said but I'll say it again, it is much easier for the cylinder to PUSH the expanding exhaust gases out than it is for it to SUCK the intake in.
Originally Posted By: Stanley Rockafeller
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Not quite. Where did you see that?
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Exhaust has both more molecules and is hotter giving a higher pressure or volume. The engineers can only cram in so much valve area. Due to the pressure differences several have cited, they give more area to the intake.
Pressure x volume = number of molecules x R (a constant) x temperature
2 molecules of octane combines with 25 molecules of oxygen to yield 16 molecules of CO2 and 18 molecules of water. At the same temperature and pressure, it would have 1.26 times the volume of the original octane and oxygen.
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Not quite. Where did you see that?
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Exhaust has both more molecules and is hotter giving a higher pressure or volume. The engineers can only cram in so much valve area. Due to the pressure differences several have cited, they give more area to the intake.
Pressure x volume = number of molecules x R (a constant) x temperature
2 molecules of octane combines with 25 molecules of oxygen to yield 16 molecules of CO2 and 18 molecules of water. At the same temperature and pressure, it would have 1.26 times the volume of the original octane and oxygen.
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Originally Posted By: labman
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Only at STP (Standard Temperature and Pressure), you know that, but not all the spectators do.
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Only at STP (Standard Temperature and Pressure), you know that, but not all the spectators do.
Originally Posted By: Stanley Rockafeller
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Nope that is the absoulute wrong reason.
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Nope that is the absoulute wrong reason.
Originally Posted By: labman
Originally Posted By: Stanley Rockafeller
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Not quite. Where did you see that?
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Exhaust has both more molecules and is hotter giving a higher pressure or volume. The engineers can only cram in so much valve area. Due to the pressure differences several have cited, they give more area to the intake.
Pressure x volume = number of molecules x R (a constant) x temperature
2 molecules of octane combines with 25 molecules of oxygen to yield 16 molecules of CO2 and 18 molecules of water. At the same temperature and pressure, it would have 1.26 times the volume of the original octane and oxygen.
In the end the exhaust gas has a thing called a piston that will push out the exhaust gas out . Really there is a piston in there.
Originally Posted By: Stanley Rockafeller
You are all wrong...seriously.
it's because the raw air/fuel molecules are larger in size than exhaust molecules.
end of discussion.
Not quite. Where did you see that?
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Exhaust has both more molecules and is hotter giving a higher pressure or volume. The engineers can only cram in so much valve area. Due to the pressure differences several have cited, they give more area to the intake.
Pressure x volume = number of molecules x R (a constant) x temperature
2 molecules of octane combines with 25 molecules of oxygen to yield 16 molecules of CO2 and 18 molecules of water. At the same temperature and pressure, it would have 1.26 times the volume of the original octane and oxygen.
In the end the exhaust gas has a thing called a piston that will push out the exhaust gas out . Really there is a piston in there.
Originally Posted By: XS650
Originally Posted By: labman
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Only at STP (Standard Temperature and Pressure), you know that, but not all the spectators do.
Good point. Thank you for the friendly correction.
Yes Steve S, a whole lot of pushing and shoving going on. First the hot gases push the piston and crank shaft journal down, then when the exhaust valve opens, they flow out it with a shove from the piston. The smaller area works because the pressure is higher.
Originally Posted By: labman
Equal numbers of molecules in any gas take up the same space. 22.4 liters of any gas, or mixture contain 6.22 x 10^23 molecules.
Only at STP (Standard Temperature and Pressure), you know that, but not all the spectators do.
Good point. Thank you for the friendly correction.
Yes Steve S, a whole lot of pushing and shoving going on. First the hot gases push the piston and crank shaft journal down, then when the exhaust valve opens, they flow out it with a shove from the piston. The smaller area works because the pressure is higher.
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