difference between cold air and short ram?
02-04-2004, 08:22 PM
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difference between cold air and short ram?
What is the difference between cold air intake and short ram intake??? Which is better for the Rx-8??? Is it also true that modified intakes should not be driven in rain, because when water gets in the intake it will mess up the whole engine??
02-04-2004, 11:35 PM
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While not a RX-8 owner I am a Z owner (both Datsun and Nissan) and have always run differnt types of intakes on my cars other than stock and being from both Washington with constant rain and Arizona with flash floods I can tell you that a properly set up intake such as the ones that you will find in the 8 will have no problems with rain. This is the same set up that the 280z's from the late seventies had, alebit a lot more inteligent the filter will not pick up a lot of moisture and what it does is mostly caught by the oil on the filter, the filter material and the rest is further atomized than it is already by the compression/ignition cycle and will be no more hazardous than damp air in Louisiana. Flooding is a problem as a aftermarket intake has no water runoff like you find in most stock boxes.
02-05-2004, 12:14 AM
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Re: difference between cold air and short ram?
Originally posted by orangematics
What is the difference between cold air intake and short ram intake???
What is the difference between cold air intake and short ram intake???
A short ram example is the K&N intake available.
No one currently has a CAI available for the RX-8 that I'm aware of.
I had a short ram on one of previous cars and also a CAI on another. I like the throttle response of the short ram over the CAI.
IMO, intakes are a waste of money for performance. If you want some sound, then they are something to get. Otherwise, stick with the stock intake. Any performance gain you'll get from an intake will be so de minimus you'll never know - except for the sound.
02-05-2004, 12:15 AM
#5
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cold air intake systems reroute the intake pipe away from the top of the engine bay...they are normally positioned somewhere below the headlights...they tend to inhale cooler air coming from the from the front of the car opposed to short ram intakes...short ram intakes tend to inhale the hot air that the engine bay creates...
02-05-2004, 01:00 AM
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There will be power differences between a short and long intake system beyond just breathing hot or cold air. The actual length of pipe tunes the intake to an extent. The longer the intake pipe the lower in the powerband the gain. The longer kits should actually give more usable power throughout the rpm range but don't expect miracles. The shorter intakes are typically louder as well. Part of this is because the filter is closer to you where you can hear it better but also because a shorter pipe is tuned to a higher frequency which is intensified by the engine rpm hitting this tuning at a higher rpm.
On my little (god forbid I admit this!) Honda Civic, I tried several different systems to see why the ricers were so intent on buying these systems. The popular short system actually hurt power and made th car much louder. The best system that I have tried on that car was one that I built from scratch. It is a long tube system with the filter in the front right corner down low behind the bumper. This system is much quieter and I actually noticed a gain over stock. Low end power is much better and the fact that gas mileage is higher than the car was rated at is proof. I used to average 28/32 mpg but after my intake I now get 32/35. Big gain from tuning where the car needs it. Why tune high when the average is low? My car is a daily driver and I rely on gas mileage. Good mod for me but the car is still pathetic and slow. My RX-7 is currently getting the same type of experimentation.
To say that a different intake doesn't give any noticable gains is a blanket statement that may or may not apply. It depends on how well the kit was designed. I am not a fan of merely jumping on the cone filter bandwagon although it may hold a little gain. The stock airbox is "tuned", aftermarket kits are based on greater flow. The stock airbox while designed very well is limited in flow. The total open area of the intake pipes is less than the area of either the maf or the throttlebody and this is a restriction that can be improved upon.
Don't believe the term "ram" as in shortram. Nothing is being "rammed" anywhere except marketing. People that believe that this system is a "ram air" system would probably benefit a little from a nice can of Vaseline. It'll hurt less that way. A true "ram air" system is designed to force air into the engine by directly putting an open intake in the path of oncoming air either through the hood or routed from the front grille area. Old muscle cars with "ram stacks" sticking through the hood or big functional scoops are true ram air systems. Racing Beat claimed that on their Bonneville cars that a true "ram air" system can add around 3 mph to the ultimate top speed of a vehicle. At very high speeds it takes quite a bit of power to go any faster since drag is an expontential increase. However for street use and the generally slow speeds (speed limits or thereabouts) that we drive at there isn't going to be a noticable gain in performance. A "cold air" system can add twice as much power as a true "ram air" system and this is the very reason why it is important to keep underhood air and heat away from the intake. My little Civic setup has several layers of Dynamat Ultra lining the intake pipe. It isn't pretty but no underhood heat gets absorbed into my intake pipe.
Throttle response should not change with filter location. The important issue is with how free flowing the entie system is. If a long system flows just as good as a short system then throttle response should not change. The key is to not use a small diameter pipe. A long system should have a pipe that is larger in area than the throttlebody that tapers down to the throttlebody size as it gets nears it. Throttlebody location is what typically determines throttle response. The closer a throttlebody to the engine the faster the throttle response. The farther, the slower. The only way a different intake system can affect throttle response is if it has inadequate flow and therefore a greater pressure drop than the system it is being tested against. Worse throttle response is a very bad sign and probably a hint that it needs to be removed.
I wouldn't worry about killing your engine from rain water. You have to physically submerge the filter in flood waters for a few seconds before the engine will suck up any water. You need to think that if there is water on even part of the filter, it is of greater pressure and much harder to inhale. The engine will just suck more air from around it. You could physically lower the bottom half of the filter in water and it still won't inhale it. There has to be a very sudden pressure drop of serious intensity such as total submersion. Then it has to last long enough that the engine sucks up this thick column of water all the way to the engine block. Even if it did suck up some water, as long as the filter was removed from submersion gravity would pull most of the water back down. Air bubbles from below the sucked up water column would be forced through and the water would just drain back down. You have to be extremely careless to kill your engine by water inhalation. I always refer to my little Civic but it is only about 6" off the ground and I have driven through some very heavy rains and even standing water. I try to be careful how deep the water is and to keep the rpm's down. The lower the rpm's the less the available suction in the intake. Also remember that the slower you go through water the less it is forced up into the front of the car. Ever seen someone going faster through water than they should? Water goes up really high in front and it is also doing the same thing in the engine ebay. Go slow and keep the rpms down. If anyone says keeping the engine revved up is a good thing, hopefully you are riding in their car. Just for safety sake I still installed an AEM bypass valve on my Civic but it actually hurt performance and my wallet at $35. It is much easier for air to just enter through this valve than a filter and it also has a crappy foam filter around it. Even when I installed it I looked at the insides of my intake pipes and there was no hint of water anywhere. Water just getting on the filter isn't even worth worrying about. Not even direct splashes.
On my little (god forbid I admit this!) Honda Civic, I tried several different systems to see why the ricers were so intent on buying these systems. The popular short system actually hurt power and made th car much louder. The best system that I have tried on that car was one that I built from scratch. It is a long tube system with the filter in the front right corner down low behind the bumper. This system is much quieter and I actually noticed a gain over stock. Low end power is much better and the fact that gas mileage is higher than the car was rated at is proof. I used to average 28/32 mpg but after my intake I now get 32/35. Big gain from tuning where the car needs it. Why tune high when the average is low? My car is a daily driver and I rely on gas mileage. Good mod for me but the car is still pathetic and slow. My RX-7 is currently getting the same type of experimentation.
To say that a different intake doesn't give any noticable gains is a blanket statement that may or may not apply. It depends on how well the kit was designed. I am not a fan of merely jumping on the cone filter bandwagon although it may hold a little gain. The stock airbox is "tuned", aftermarket kits are based on greater flow. The stock airbox while designed very well is limited in flow. The total open area of the intake pipes is less than the area of either the maf or the throttlebody and this is a restriction that can be improved upon.
Don't believe the term "ram" as in shortram. Nothing is being "rammed" anywhere except marketing. People that believe that this system is a "ram air" system would probably benefit a little from a nice can of Vaseline. It'll hurt less that way. A true "ram air" system is designed to force air into the engine by directly putting an open intake in the path of oncoming air either through the hood or routed from the front grille area. Old muscle cars with "ram stacks" sticking through the hood or big functional scoops are true ram air systems. Racing Beat claimed that on their Bonneville cars that a true "ram air" system can add around 3 mph to the ultimate top speed of a vehicle. At very high speeds it takes quite a bit of power to go any faster since drag is an expontential increase. However for street use and the generally slow speeds (speed limits or thereabouts) that we drive at there isn't going to be a noticable gain in performance. A "cold air" system can add twice as much power as a true "ram air" system and this is the very reason why it is important to keep underhood air and heat away from the intake. My little Civic setup has several layers of Dynamat Ultra lining the intake pipe. It isn't pretty but no underhood heat gets absorbed into my intake pipe.
Throttle response should not change with filter location. The important issue is with how free flowing the entie system is. If a long system flows just as good as a short system then throttle response should not change. The key is to not use a small diameter pipe. A long system should have a pipe that is larger in area than the throttlebody that tapers down to the throttlebody size as it gets nears it. Throttlebody location is what typically determines throttle response. The closer a throttlebody to the engine the faster the throttle response. The farther, the slower. The only way a different intake system can affect throttle response is if it has inadequate flow and therefore a greater pressure drop than the system it is being tested against. Worse throttle response is a very bad sign and probably a hint that it needs to be removed.
I wouldn't worry about killing your engine from rain water. You have to physically submerge the filter in flood waters for a few seconds before the engine will suck up any water. You need to think that if there is water on even part of the filter, it is of greater pressure and much harder to inhale. The engine will just suck more air from around it. You could physically lower the bottom half of the filter in water and it still won't inhale it. There has to be a very sudden pressure drop of serious intensity such as total submersion. Then it has to last long enough that the engine sucks up this thick column of water all the way to the engine block. Even if it did suck up some water, as long as the filter was removed from submersion gravity would pull most of the water back down. Air bubbles from below the sucked up water column would be forced through and the water would just drain back down. You have to be extremely careless to kill your engine by water inhalation. I always refer to my little Civic but it is only about 6" off the ground and I have driven through some very heavy rains and even standing water. I try to be careful how deep the water is and to keep the rpm's down. The lower the rpm's the less the available suction in the intake. Also remember that the slower you go through water the less it is forced up into the front of the car. Ever seen someone going faster through water than they should? Water goes up really high in front and it is also doing the same thing in the engine ebay. Go slow and keep the rpms down. If anyone says keeping the engine revved up is a good thing, hopefully you are riding in their car. Just for safety sake I still installed an AEM bypass valve on my Civic but it actually hurt performance and my wallet at $35. It is much easier for air to just enter through this valve than a filter and it also has a crappy foam filter around it. Even when I installed it I looked at the insides of my intake pipes and there was no hint of water anywhere. Water just getting on the filter isn't even worth worrying about. Not even direct splashes.
Last edited by rotarygod; 02-05-2004 at 01:07 AM.
02-06-2004, 11:35 AM
#9
Registered User
I'm in agreement with RotoryGod. Another point that we've seen on our cars is that some cars don't react well with either a CAI or short ram. The mass air flow sensor sometimes can get confused with a CAI and sometimes the same can happen with a short ram. I've been speaking with the engineirs at K&N since they started working on a system for the RX8. At first they made and tried a longer CAI. The gains that they saw were minimal. They tried bending it different ways to get some better dyno numbers but didn't get anything better. The short ram made noticable power right away. What can you do but shrug your shoulders and go with it.
I've read before somewhare (I'll have to find the article) that there is an acctual mathmatical equation that can be applied to the debate between CAI and Short ram. Basically the gist of it was this:
1-CAI inhale colder air from the front of the car. Colder air is more dense. The more dence it is the more can be cramed into the combustion chamber creating more H/P. (this is why turbos and SC work so well)
2-short ram pulls in some heat from the engine bay, but pulls in a larger volume of air with out the turbulence of a CAI.
-In a nut shell the article states that in most cars while simulating daily driving the two intake perform just about the same. Reason: When moving the air temp in the engine bay is usualy only about a few deg difference due to moving out side air through the front of the car and circulating around the motor. This of is whare the MAF sensor comes into play.
On my old Firebird the CAI worked better than the short ram, on my WRX the short ram worked better. (again shrugging shoulders) Dang MAF. That's why you see cars pushing REAL power have the MAF removed and running on some stand alone engine management.
I've read before somewhare (I'll have to find the article) that there is an acctual mathmatical equation that can be applied to the debate between CAI and Short ram. Basically the gist of it was this:
1-CAI inhale colder air from the front of the car. Colder air is more dense. The more dence it is the more can be cramed into the combustion chamber creating more H/P. (this is why turbos and SC work so well)
2-short ram pulls in some heat from the engine bay, but pulls in a larger volume of air with out the turbulence of a CAI.
-In a nut shell the article states that in most cars while simulating daily driving the two intake perform just about the same. Reason: When moving the air temp in the engine bay is usualy only about a few deg difference due to moving out side air through the front of the car and circulating around the motor. This of is whare the MAF sensor comes into play.
On my old Firebird the CAI worked better than the short ram, on my WRX the short ram worked better. (again shrugging shoulders) Dang MAF. That's why you see cars pushing REAL power have the MAF removed and running on some stand alone engine management.
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