Ram effect
Teching In
Joined: Mar 2006
Posts: 44
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Okay here are some numbers that show how much ram air induction works. This guy went to the trouble of calculating volumetric efficiency with ram air induction and took the temperature change of the cold air into account. He basicaly got a .9% increase .
http://www.installuniversity.com/ins..._12.262000.htm
"The test runs were made in the first three gears of a six-speed LS1. That puts the LS1 rifling along at 100 mph plus at the end of the test run, just like at the nearest quarter-mile drag way. In first gear, the VE showed no gain. During second gear, an increase of 0.9 percent was shown over the stock configuration. Third gear showed the exact same increase over the stock configuration. A 0.9 percent increase in volumetric efficiency stuffs an extra 31 cubic inches of air into the engine."
Now be fore some one says "See he had to go 100mph to notice the change" I will point out that the test ended at just over 100 mph in 3rd and he noted the same basic increase in 2nd gear. So unless he did 70mph in first there are gains at normal speeds.
Note: He also mentioned an increase mileage in this write up.
http://www.installuniversity.com/ins..._12.262000.htm
"The test runs were made in the first three gears of a six-speed LS1. That puts the LS1 rifling along at 100 mph plus at the end of the test run, just like at the nearest quarter-mile drag way. In first gear, the VE showed no gain. During second gear, an increase of 0.9 percent was shown over the stock configuration. Third gear showed the exact same increase over the stock configuration. A 0.9 percent increase in volumetric efficiency stuffs an extra 31 cubic inches of air into the engine."
Now be fore some one says "See he had to go 100mph to notice the change" I will point out that the test ended at just over 100 mph in 3rd and he noted the same basic increase in 2nd gear. So unless he did 70mph in first there are gains at normal speeds.
Note: He also mentioned an increase mileage in this write up.
Teching In
Joined: Mar 2006
Posts: 44
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You will also note his calculations give you the increase of air in cubic inches of air not pounds of air. If you would like to see how he did the calculations http://www.installuniversity.com/ins...n_9.012000.htm
The MAF sensor measures mass not volume of air. The reason he needed to know the temperature was to calculate the density of the air so he could calculate volume.
Volumetric efficiency is defined as the percentage of actual volume of flow of the theoretical volume of flow. Seeing as how volumetric efficiency is volume based measurement and not mass based measurement, neglecting differences in aerodynamic drag of the denser air, the volumetric efficiency of an engine is independent of air density and temperature.
The MAF sensor measures mass not volume of air. The reason he needed to know the temperature was to calculate the density of the air so he could calculate volume.
Volumetric efficiency is defined as the percentage of actual volume of flow of the theoretical volume of flow. Seeing as how volumetric efficiency is volume based measurement and not mass based measurement, neglecting differences in aerodynamic drag of the denser air, the volumetric efficiency of an engine is independent of air density and temperature.
He calculates a 14 hp increase, and shows a 7 100th's gain in ET and a .4 mph increase in the quarter due to the switch. This gain INCLUDES the fact that the unit is pulling in 10-15 degree cooler air ? I have seen countless people shows these gains with just a cold-air kit or lid.
How does this show that Ram-air works? If anything, I see it proving the opposite. Even with a 10 degree cooler intake charge, AND a ram-air system ... you only pick up a .07 second increase in ET.
Granted, an increase is an increase, and I'm not saying don't to do it ... I agree that ram-air in general works, however, at the speeds a normal car sees the improvement is relatively insignificant. Giving the engine 10-20 degree cooler air will be a much larger benefit then a pure 'ram-air' based system would.
How does this show that Ram-air works? If anything, I see it proving the opposite. Even with a 10 degree cooler intake charge, AND a ram-air system ... you only pick up a .07 second increase in ET.
Granted, an increase is an increase, and I'm not saying don't to do it ... I agree that ram-air in general works, however, at the speeds a normal car sees the improvement is relatively insignificant. Giving the engine 10-20 degree cooler air will be a much larger benefit then a pure 'ram-air' based system would.
On The Tree
Joined: Jun 2003
Posts: 150
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Good Ram air - tiny gains, real, but small and expensive
Average Ram air - no gains (like factory ram air)
Bad Ram air - no gains, plus some drag (someone mentioned a tuba, think tiny paracute)
How about this for a test? Can someone put a ram air car on a dyno with a fan to similate wind (like a wind tunnel, not a table fan) and a heater in the intake rigged to maintain a constance IAT across all tests? The difference in HP between fan blowing 100mph (or whatever) and fan turned off will tell you what difference ram air makes in the real world once and for all.
"Why would everyone do it if it doesn't work?" People do all kinds of stupid crap. Don't you tell your kids "If everyone else was jumping off a bridge would you?" Serious racers do it because they need every last gain, no matter how small or expensive.
Theory or Track Results? How about both? Theory alone won't work, because none of us are as smart as we like to think we are. Track Results alone won't work, because if you don't understand the theory, you can't even know what the results mean.
Average Ram air - no gains (like factory ram air)
Bad Ram air - no gains, plus some drag (someone mentioned a tuba, think tiny paracute)
How about this for a test? Can someone put a ram air car on a dyno with a fan to similate wind (like a wind tunnel, not a table fan) and a heater in the intake rigged to maintain a constance IAT across all tests? The difference in HP between fan blowing 100mph (or whatever) and fan turned off will tell you what difference ram air makes in the real world once and for all.
"Why would everyone do it if it doesn't work?" People do all kinds of stupid crap. Don't you tell your kids "If everyone else was jumping off a bridge would you?" Serious racers do it because they need every last gain, no matter how small or expensive.
Theory or Track Results? How about both? Theory alone won't work, because none of us are as smart as we like to think we are. Track Results alone won't work, because if you don't understand the theory, you can't even know what the results mean.
I didn't read this post. But here is the simplest method:
Place a pressure transducer in front of the MAF sensor which measures absolute pressure. Do this on the same car with and without ram-air. You'll need some data aquisition software like LabView and record the data on a quarter mile pass. You'll also need to log your speed.
Place a pressure transducer in front of the MAF sensor which measures absolute pressure. Do this on the same car with and without ram-air. You'll need some data aquisition software like LabView and record the data on a quarter mile pass. You'll also need to log your speed.
Originally Posted by algws6
guys help me out on this one
http://forums.corvetteforum.com/show...post1555003355
http://forums.corvetteforum.com/show...post1555003355
the best thing about the vararam is that it actually pulls in "fresh" air.
i use one. i cant say that i actually felt much diff in performance from my old stinger setup, im running a maggy so its sucking in much much more than what any "ram" effect could preduce....
BUT! when loggin i see the iat's are much lower when moving as compared to my older stinger intake.
FWIW
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Verdad Gallardo Teching In
Joined: Mar 2006
Posts: 44
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Originally Posted by algws6
one guy posted a test where they had huge gas powered compresors and ran ducts to the inlet of some crotch rockets and that is his proof that it works. read the last two pages.
