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Question on GT500 Engine Cubic Inches


HSURB

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Let me see if i can stir the pot a bit....what does the blower "add" in displacement?

 

Is this a trick question? I'll throw my answer in, assuming you are asking seriously.

 

The short answer:

It adds nothing to displacement.

 

The long answer:

Displacement is found by taking the bore (area of the cross-section of the cylindrical hole in the block) x the stroke (the distance the piston travels inside said hole) x the number of cylinders in the block (a unitless factor). Area x length = volume, which is why displacement is given as a volume. The blower does not change anything that determines displacement.

 

What the blower does change is how much air is forced into that volume. PV=nRT is about as basic a law for gases as there is. P = pressure, V = volume, n = number of moles of gas (air in this case - technically air/fuel mixture), R = the Universal Gas Constant, and T = temperature. Since a mole of gas contains 6.023x10 to the 23rd power (can't figure out superscript here) atoms of gas, it might be easier to think in terms of atoms. So this formula can also be written as PV=NkT, where N = the number of atoms of gas, and k = Boltzmann's Constant.

 

In our case, we have determined that volume is constant. So the only variable on the left side is pressure. Boltzmann's Constant is obviously a constant (call me Captain Obvious), so the variables on the right side are the number of atoms of gas and the temperature of that gas. The blower can cause one, or usually both, of the right side variables to increase, which in turn causes the pressure to increase. Therefore the blower causes an increase in pressure, not displacement. Which is why Ford spent all that money to put a gauge on your dash indicating boost pressure.

 

Wow. I didn't think all those High School Physics and College weed-out courses found a home in my brain. Mr. Bowers would be proud.

 

Now I'll wait for Dan to wander in and shoot that explanation down.

 

***EDIT: Typos***

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Is this a trick question? I'll throw my answer in, assuming you are asking seriously.

 

The short answer:

It adds nothing to displacement.

 

The long answer:

Displacement is found by taking the bore (area of the cross-section of the cylindrical hole in the block) x the stroke (the distance the piston travels inside said hole) x the number of cylinders in the block (a unitless factor). Area x length = volume, which is why displacement is given as a volume. The blower does not change anything that determines displacement.

 

What the blower does change is how much air is forced into that volume. PV=nRT is about as basic a law for gases as there is. P = pressure, V = volume, n = number of moles of gas (air in this case - technically air/fuel mixture), R = the Universal Gas Constant, and T = temperature. Since a mole of gas contains 6.023x10 to the 23rd power (can't figure out superscript here) atoms of gas, it might be easier to think in terms of atoms. So this formula can also be written as PV=NkT, where N = the number of atoms of gas, and k = Boltzmann's Constant.

 

In our case, we have determined that volume is constant. So the only variable on the left side is pressure. Boltzmann's Constant is obviously a constant (call me Captain Obvious), so the variables on the right side are the number of atoms of gas and the temperature of that gas. The blower can cause one, or usually both, of the right side variables to increase, which in turn causes the pressure to increase. Therefore the blower causes an increase in pressure, not displacement. Which is why Ford spent all that money to put a gauge on your dash indicating boost pressure.

 

Wow. I didn't think all those High School Physics and College weed-out courses found a home in my brain. Mr. Bowers would be proud.

 

Now I'll wait for Dan to wander in and shoot that explanation down.

 

***EDIT: Typos***

 

 

 

Wow is it snowing in PA.?You have way to much free time.Your answer is good though. :headspin:

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Maybe he was asking how much volume would the supercharged air take up, if its pressure were reduced to atmospheric. For example, maybe 5.4L of air at 8 lbs of pressure would be equivalent to 7.5L at atmospheric pressure, or something along those lines.

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Maybe he was asking how much volume would the supercharged air take up, if its pressure were reduced to atmospheric. For example, maybe 5.4L of air at 8 lbs of pressure would be equivalent to 7.5L at atmospheric pressure, or something along those lines.

 

 

Also, the compressed air would have an elevated temperature, so not only would you have to factor the pressure reduction, but also a temperature reduction.

 

I understand what you're saying, though, and it would be easy to calculate. As long as we had IATs with and without blower, and a boost gauge reading for the blower - although we could assume 8.5 psi at WOT.

 

I took his question literally, which is why I said the displacement isn't affected by the blower.

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Is this a trick question? I'll throw my answer in, assuming you are asking seriously.

 

The short answer:

It adds nothing to displacement.

 

The long answer:

Displacement is found by taking the bore (area of the cross-section of the cylindrical hole in the block) x the stroke (the distance the piston travels inside said hole) x the number of cylinders in the block (a unitless factor). Area x length = volume, which is why displacement is given as a volume. The blower does not change anything that determines displacement.

 

What the blower does change is how much air is forced into that volume. PV=nRT is about as basic a law for gases as there is. P = pressure, V = volume, n = number of moles of gas (air in this case - technically air/fuel mixture), R = the Universal Gas Constant, and T = temperature. Since a mole of gas contains 6.023x10 to the 23rd power (can't figure out superscript here) atoms of gas, it might be easier to think in terms of atoms. So this formula can also be written as PV=NkT, where N = the number of atoms of gas, and k = Boltzmann's Constant.

 

In our case, we have determined that volume is constant. So the only variable on the left side is pressure. Boltzmann's Constant is obviously a constant (call me Captain Obvious), so the variables on the right side are the number of atoms of gas and the temperature of that gas. The blower can cause one, or usually both, of the right side variables to increase, which in turn causes the pressure to increase. Therefore the blower causes an increase in pressure, not displacement. Which is why Ford spent all that money to put a gauge on your dash indicating boost pressure.

 

Wow. I didn't think all those High School Physics and College weed-out courses found a home in my brain. Mr. Bowers would be proud.

 

Now I'll wait for Dan to wander in and shoot that explanation down.

 

***EDIT: Typos***

 

+1 ORF I`am sure Dan will agree.

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