age old question: short ram or cold air intake?
#11
01-06-2008, 07:38 AM
RE: age old question: short ram or cold air intake?
ORIGINAL: conceptualpolymer
Yes, the filter surface area will make a difference, but the biggest difference comes when comparing a hot or cold air system. In larger computer-controlled engines, a cold air system will prevent HP loss due to hot engine bay air being ingested by the engine intake. Both a short ram and CAI system will produce gains over the factory air box, but the cold air system will actually maintain all the extra power at all times, specifically after stop & go and slow-moving traffic conditions.
Take virtually ANY compressor or vacuum pump, run it until it gets hot and see what happens to its max pressure or vacuum levels (they drop). Now blow cold air on either to see the difference. Look at many sports cars like the Z06, Viper, Subaru STI, and Mitsu EVO. Their intake filters are directly exposed to a constant stream of cold air, useally via an opening in the hood or front facia.
Cold air DOES make a difference; whether that difference is easily noticed is another matter, but if you want to keep those extra 5 horses, keep your engine fed with the coldest air you can give it.
Yes, the filter surface area will make a difference, but the biggest difference comes when comparing a hot or cold air system. In larger computer-controlled engines, a cold air system will prevent HP loss due to hot engine bay air being ingested by the engine intake. Both a short ram and CAI system will produce gains over the factory air box, but the cold air system will actually maintain all the extra power at all times, specifically after stop & go and slow-moving traffic conditions.
Take virtually ANY compressor or vacuum pump, run it until it gets hot and see what happens to its max pressure or vacuum levels (they drop). Now blow cold air on either to see the difference. Look at many sports cars like the Z06, Viper, Subaru STI, and Mitsu EVO. Their intake filters are directly exposed to a constant stream of cold air, useally via an opening in the hood or front facia.
Cold air DOES make a difference; whether that difference is easily noticed is another matter, but if you want to keep those extra 5 horses, keep your engine fed with the coldest air you can give it.
And just to point out: it's arguable whether or not cold-air intakes actually bring in that much cold air since the aluminum tube can act as a heat sink. (not trying to start an arguement, but I figured I'd point that out)
#12
01-06-2008, 03:38 PM
RE: age old question: short ram or cold air intake?
Normally, I'd agree, but AEM provides good reasons (in their website) why the material is not that important. Apparently, they have tested plastics and metals, only to find that the velocity of the intake air is high enough so that heat from outside the tube doesn't have a chance to "heat soak" the air inside. Now if you shut the car off and within an hour or so, turn it back on, there will be a brief blast of warm air into the intake, but that is momentary, at best.
And yes, "seat-of-the-pants" feeling of extra power won't be there, but the 1/8th and 1/4 drag times will show the difference. I plugged in a "Car Chip" data logger into my other car's OBD II connector. The Car Chip can record a wide variety of operating parameters like intake air temp, fuel trim, coolant temp, vehicle speed, etc, etc. When using my "short ram" intake, intake air temps would skyrocket while driving in the city, resulting in retardation of timing and a 10HP reduction. After installing a scoop, cutting the lower radiator cover, and installing stainless steel screen underneath the air filter, I ran the same course with a 40 degree F reduction in intake air temperature. Don't let anyone fool you into thinking that there is little difference between warm air and cold air. I have reams of data that shows the huge intake air temperature difference.
Dave
And yes, "seat-of-the-pants" feeling of extra power won't be there, but the 1/8th and 1/4 drag times will show the difference. I plugged in a "Car Chip" data logger into my other car's OBD II connector. The Car Chip can record a wide variety of operating parameters like intake air temp, fuel trim, coolant temp, vehicle speed, etc, etc. When using my "short ram" intake, intake air temps would skyrocket while driving in the city, resulting in retardation of timing and a 10HP reduction. After installing a scoop, cutting the lower radiator cover, and installing stainless steel screen underneath the air filter, I ran the same course with a 40 degree F reduction in intake air temperature. Don't let anyone fool you into thinking that there is little difference between warm air and cold air. I have reams of data that shows the huge intake air temperature difference.
Dave
#13
01-06-2008, 03:49 PM
RE: age old question: short ram or cold air intake?
^^Do you think getting a hood with vents on the top would help dissipate heat from the header away from the filter to make as noticeable a difference as fabricateing a scoop from underneath? Aswell as bringing in colder air from above?
#14
01-06-2008, 07:33 PM
RE: age old question: short ram or cold air intake?
That depends on where the air is directed, but without a doubt, it would help keep the intake air temps down. Some of the old muscle cars had functional hood scoops at the top of their hoods. This location was ideal because the air filter sat on top of the engine (the hottest area in the engine bay). Most cars now have intake filters mounted to the side or down in front of the engine.
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