Cold air intakes

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Making a CAI, or a shortram intake
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This is really quite simple; a great project for the budding automotive enthusiast.
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==Introduction==
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Cold air induction can add (or maintain) power by feeding the engine colder outside air rather than the engine ingesting the preheated underhood air. The difference can be fairly significant, especially with high output/high performance engines.
  
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First you need to know the diameter of the stock intake tubing, and where you want your filter- usually a cone type reusable gauze type from S&B or K&N work well for these applications.
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Cold air induction can allow for richer carburetion  tuning with an increase in power. It can also reduce the tendency for detonation.
  
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Second, you need to be sure to provide fittings for vaccum and pcv lines, or if it won't upset sensors capping them off or putting a breather on works as well (with my Saturn shown in the pic, I capped off the pcv provision and put a KN breather on).  Also ensure provisions for sensors, although intake air temp sensors may be placed relatively near the air filter, or a cooler location for a slightly richer mixuture if that's desired.  I would not risk upsetting sensor readings by cutting and splicing the wires on it though.
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==Ford Thunderbolt==
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When the subject of cold air induction comes up, the first car some may think of is the 1964 Ford Fairlane Thunderbolt.  
  
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Third you need the right assortment of elbows, tubing, clamps, and possibly some length of pcv hose if the stock stuff cannot reach the nipples on the pipe that the pcv lines are to connect to.  Sometimes grabbing a dirt cheap intake kit is useful for the smooth piping to replace the bumpy crappy factory stuff.
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Dearborn Steel Tubing (known as DST) purpose built these cars for NHRA Super Stock drag racing for Ford. The engines that they used were the (very underrated) 425 HP, 427 cid high riser side oiler.  
  
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So now you have measured everything- length, diameter, etcetera. You have your supplies, and now you test fit everything without clamps and adjust as necessary to get everything to fit as you want; once that is achieved, install clamps and filter, connect pcv lines and sensors, and there you go!
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To feed cold air to a engine of this size required large (~6" diameter) tubing connected to a large aluminum air plenum box atop the dual 4 barrel carbs. The large air box required a bulge in the hood, and to get cold air from the frontal area to the large intake box, the designers used the area where the inner headlights normally resided for the intake. They added grills to keep out large debris, and ran the ducting up to the intake box (seen below). The result was the iconic look of the Ford Thunderbolt.
  
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The main difference between a cold air intake and a shortram is that a shortram is simpler, and the filter is in the engine compartment, drawing in warmer air. A cold air intake is more complicated and the filter is usually in the fender or otherwise isolated from engine compartment heat.
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[[Image:Headlight_intake_grill.jpg|thumb|center|400px|Cold air intake]]
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{|
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|[[Image:Side_view_of_cold_air_intakes.jpg|thumb|center|370px|]]
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|[[Image:Dual_intake_pipes.jpg|thumb|center|370px|]]
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|}
  
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==Fabricating a cold air induction system==
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This is really quite simple; a great project for the budding automotive enthusiast. A homemade cold air intake can be built using nothing more complicated than coffee cans and dryer duct, the can can be pop riveted to the air cleaner sides after cutting a hole the shape and size desired. Then route the dryer ducting to a source of outside air. On older vehicles, this was usually from the grill area or under the bumper. This isn't the prettiest or most efficient set-up, but illustrates the basic concept can be adapted using low-tech methods and materials.
  
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== Ram Air Systems ==
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==Design considerations==
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Generally speaking, bigger is better because it is less restrictive. However, packaging the system under the hood has to be a consideration.
  
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First you need to know the diameter of the stock intake tubing (if it is to be used/reused) or the size and shape of the air cleaner snorkel if it's to be used. If using a remote filter like a cone type reusable gauze filter, the location needs to be selected based on available space and a suitable carb "hat" needs to be bought or fabricated.
  
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There some other methods used to achieve cold air to the engine. Now the major part of the horsepower gains are from the engine seeing colder (more dense) exterior air as opposed to hot underhood air. By looking at the aerodynamics of a moving car we can also pick up some ram air effect by careful placement of the air intake. There are basically two areas of high pressure found on a normal passenger car. The first is at the front of the car in the grille area and the other is at the intersection of the base of the windshield and the hood. By locating our air intake in either area we can show a gain.
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==Late model production vehicles==
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In most cases, the late model passenger car/light trucks on the road today are using some sort of cold air intake. If the air filter housing/box is located on one side or the other of the engine compartment, and has ducting that goes through the inner fender, this duct work is pulling in outside air. Most aftermarket cold air intake kits include ducting that is smooth, not ribbed or corrugated. This allows for less disruption of the airflow, which is also beneficial in combination with the cold air intake.
  
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The simple way to do this is to use some of the aluminum dryer vent tube (the flexible kind) and route it from behind the grille to the existing air cleaner housing. This works on the older cars that did not have exterior air routed to the engine. A solution that is a bit more work is to cut some holes in the air intake vent inside the enigine compartment to access cold air from the base of the windshield. make some collars to be pop riveted in and run your dryer vent to the air cleaner.
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A high flow air filter in a stock intake box/housing with smooth ducts can work well on late model applications, sometimes as well as the high dollar kits sold in the aftermarket. In these cases the only "advantage" to the aftermarket kit is the looks.
  
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More to come
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==Potential gains==
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A law of physics states that for each 10º drop in air temperature going into the motor, power will pick up by 1%. This is because when the air is colder, it is more dense and therefore contains more oxygen. So potentially, a 100º drop in air temperature would equate to a 10% increase in power. On a 400 hp motor, this would equal a 40 hp power increase.
  
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Of course, a tuner would have to compensate for more oxygen by jetting richer to correct the air/fuel mixture. The later model EFI systems sense more oxygen and automatically richen the mixture.
  
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Hi fellows, techinspector1 here. I'm still tech inspecting at Firebird International Raceway in Phoenix and want to pass on some basic information on the subject of cold air intakes. I constantly see installations that have been done with K&N and other filter assemblies with the filter in the engine compartment, usually right behind the radiator.
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[[Category:Engine]]
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[[Category:Carburetors]]
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Common sense should tell you that you are picking up 200 degree air right behind the radiator, but I guess common sense isn't all that common anymore. Run your ducting to the outside of the car to pick up cooler ambient air and you'll pick up power. For each 10 degrees of lower air temperature you duct to the intake, you pick up an additional 1 percent power (rejetted of course to take advantage of the denser air). Here in Phoenix where the ambient can easily be 100 degrees, a change from underhood air at 200 degrees to ambient air at 100 degrees can mean a 10 percent increase in power.
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techinspector1
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Latest revision as of 07:06, 31 March 2012

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