Do air inlets actually make power?
02-12-2009, 04:44 PM
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Do air inlets actually make power?
So I have looked on the forums and I have looked on the web. Does anyone have a before and after dyno of someone who installed one of those air inlet ducts like this.
I mean the idea behind it seems sound but I would like to see some proof behind the pudding you know.
Also if you installed on afterwards what was your impression besides other mods.
I don't really care for the look, but it isn't bad and if it works it is functional which is what matters to me.
I mean the idea behind it seems sound but I would like to see some proof behind the pudding you know.
Also if you installed on afterwards what was your impression besides other mods.
I don't really care for the look, but it isn't bad and if it works it is functional which is what matters to me.
02-12-2009, 06:23 PM
#4
The problem with measuring something like that, is that when on most dyno's they simply put a fan in the grill to keep the car from overheating. To properly test something like that requires air to be directed into the duct.
I've been running one of these for about a year now,
\
I'll say that I noticed the gains from highway speeds onward. It just seemed to pulled harder from 60+. Is there any merit to this? No. My butt dyno is horribly inaccurate and most likely doesn't share the same calibration as yours. IMHO, do it for looks, the Z has one of the better stock airboxes on the market and provides a good location for aftermarket air filters. I would consider it a visual enhancement, but personally, I wouldn't cut a hole in the bumper...
I've been running one of these for about a year now,
\I'll say that I noticed the gains from highway speeds onward. It just seemed to pulled harder from 60+. Is there any merit to this? No. My butt dyno is horribly inaccurate and most likely doesn't share the same calibration as yours. IMHO, do it for looks, the Z has one of the better stock airboxes on the market and provides a good location for aftermarket air filters. I would consider it a visual enhancement, but personally, I wouldn't cut a hole in the bumper...
Last edited by FORZWIN; 02-12-2009 at 06:26 PM.
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02-16-2009, 08:45 AM
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Measure the pressure above the normal 14.7 psi [sea level] in front of MAF with a manometer [one that accurate in 0.1" H2O increments].
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
02-16-2009, 02:58 PM
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Measure the pressure above the normal 14.7 psi [sea level] in front of MAF with a manometer [one that accurate in 0.1" H2O increments].
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
02-17-2009, 02:34 PM
#13
Measure the pressure above the normal 14.7 psi [sea level] in front of MAF with a manometer [one that accurate in 0.1" H2O increments].
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
02-17-2009, 06:28 PM
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Measure the pressure above the normal 14.7 psi [sea level] in front of MAF with a manometer [one that accurate in 0.1" H2O increments].
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
Those were my thoughts exactly also.
02-19-2009, 05:32 PM
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Actually not, as even a very poorly designed duct will still be pressurized by the 14.7 psi.
Now if the area of the duct were smaller than the MAF it would start to offer some resistance but even a 2-3" hole would be pretty insignificant due to small displacement of engine.
215 ci/2 = 107ci per rev x 6000 rpm = 642000/1728 = 371.5 CFM max and usually more like x 0.85 = ~ 315 CFM.
Now if the area of the duct were smaller than the MAF it would start to offer some resistance but even a 2-3" hole would be pretty insignificant due to small displacement of engine.
215 ci/2 = 107ci per rev x 6000 rpm = 642000/1728 = 371.5 CFM max and usually more like x 0.85 = ~ 315 CFM.
02-20-2009, 06:17 AM
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Measure the pressure above the normal 14.7 psi [sea level] in front of MAF with a manometer [one that accurate in 0.1" H2O increments].
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
1.0 PSI = 27.7" H20
The problem is the engine is already supplied with 14.7 psi [29.92126" HG] of atmospheric pressure..........................why a supercharger with 1.00 PSI of boost only adds 6.8% more air.
"The pressure build-up can be defined using the Pitot-static tube theory:
P = .5 x r x v2
Pressure (P) is force divided by an area. In the English system of measurement the units of pressure are (lb - force)/in2 which translates to psi. Density (r) is mass divided by volume. The units of density in the English system are (lb - mass)/in3. Velocity (v) is air speed, with units ft/sec. Plotting pressure vs. speed gives a graph that has theoretical pressure rising with the square of speed, and this is why ram air has much more effect at greater speeds. For a speed of 150 mph, the resulting maximum theoretical pressure would be about 27mb (approximately .4 psi). "
So at 150 mph a well designed duct could increase air flow into engine by 0.4 x 0.068 or 2.72%
But what are we looking at here, pressure or flow? If I take a volume say 200 cc and lower the pressure to 1"Hg and then open a 1.9" dia valve at a given slope time, how fast will the volume fill to atmosperic pressure? Will a few inwc of pressure speed the process?
If I have a filter that causes a 2"wc drop across it an I increase the incoming pressure by a couple of inches, would I see more flow across the filter and thus more flow to the engine.
There are far to many unanswered variables here to make a blanket statement that seems to push the pressure advantages of a moving vehicle out the window.
02-21-2009, 01:20 PM
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Like I said the general idea of ramming air into the engine from the cars momentum seems to work in theory, but I wish there was data to support it. Then again I am sure if it did work the original design of the Z and the GTR would have used it.
02-22-2009, 07:45 AM
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Actually not, as even a very poorly designed duct will still be pressurized by the 14.7 psi.
Now if the area of the duct were smaller than the MAF it would start to offer some resistance but even a 2-3" hole would be pretty insignificant due to small displacement of engine.
215 ci/2 = 107ci per rev x 6000 rpm = 642000/1728 = 371.5 CFM max and usually more like x 0.85 = ~ 315 CFM.
Now if the area of the duct were smaller than the MAF it would start to offer some resistance but even a 2-3" hole would be pretty insignificant due to small displacement of engine.
215 ci/2 = 107ci per rev x 6000 rpm = 642000/1728 = 371.5 CFM max and usually more like x 0.85 = ~ 315 CFM.
Last edited by foreveryoung; 02-22-2009 at 07:47 AM. Reason: more not less
03-01-2009, 10:29 PM
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http://autospeed.com/cms/A_0629/article.html
read this and all the articles at the bottom
they do it on a turbo car but the info can transfer over to NA cars
read this and all the articles at the bottom
they do it on a turbo car but the info can transfer over to NA cars
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