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| − | Making a CAI, or a shortram intake
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| − | When I think of Cold Air Intakes, the first car that I think of is the 1964 Ford Fairlane THUNDERBOLT. Detroit Steel Tubing, known as DST purpose built these cars for drag racing for Ford. The engines that they were using were 425 HP 427 Cu. In. How do you feed cold air to a engine of this size? BIG PIPES! How big? About 6 inch diameter. When you need to get cold air from the frontal area to the gigantic carb intake you take the most direct route. Kick out the inner headlights (who needs four headlights on a drag strip), add some grills to keep out large debris, run the expansion pipe up to the aluminum intake box and you have it. Check out the pictures on how they did it back in 1964.
| + | ==Introduction== |
| | + | 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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| − | [[Image:Headlight_intake_grill.jpg]]
| + | 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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| | + | ==Ford Thunderbolt== |
| | + | 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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| − | [[Image:Side_view_of_cold_air_intakes.jpg]]
| + | 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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| | + | 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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| − | [[Image:Dual_intake_pipes.jpg]] | + | [[Image:Headlight_intake_grill.jpg|thumb|center|400px|Cold air intake]] |
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| | + | |[[Image:Side_view_of_cold_air_intakes.jpg|thumb|center|370px|]] |
| | + | |[[Image:Dual_intake_pipes.jpg|thumb|center|370px|]] |
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| − | Of course, other people have their own views on what cold air intakes should be, and they're entitled to them. '''BIG IS BETTER'''
| + | ==Fabricating a cold air induction system== |
| | + | 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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| | + | ==Design considerations== |
| | + | 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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| − | This is really quite simple; a great project for the budding automotive enthusiast.
| + | 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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| − | First you need to know the diameter of the stock intake tubing, and where you want your filter- usually a cone type reusable gauze filter.
| + | ==Late model production vehicles== |
| | + | 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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| | + | 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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| − | Then you look under the hood...
| + | ==Potential gains== |
| − | It probably looks something like this
| + | 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. |
| − | [[Image:http://www.ayocee.com/cmine/albums/oilchhowtwo/normal_Oil%20Change%20Howto%20002.jpg]]
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| − | It's a stock 1.9L Saturn engine, of the SOHC (single over head cam) variety. Notice the stock intake tubing on the right side of the picture. It's designed to be cheap to make, reduce noise, and be easy for the guy on the production line to install, with minimal care for performance, especially in a non-sports car (think Corvette or Porsche).
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| − | Take the measurements of the throttle body outside diameter (OD) and head to the parts store. Since the throttle body is horizontal (if it were a carb, it'd be a sidedraft), you'll need a 90-degree elbow to follow the general path of the stock stuff that has . Make sure it's heat and oil resistant, and then get some tubing with the same inside diameter (ID) as the throttle body. The intake tubing (some people use pvc pipe, I prefer metal such as aluminum) needs to have the OD the same as the ID of the 90* elbow. Using various parts, being creative and inventive, piece these together ensuring you have enough room for the air filter at the end!
| + | 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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| − | Lastly, make sure you have provisions for crankcase lines (or a crankcase breather filter) and have enough hose clamps for all joints in the system. The picture below is of a Saturn 1.9L engine (the twin cam variety) with a shortram intake. It's not a true cold air intake since the air going into the engine is from the engine compartment.
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| − | [[Image:http://hotrodders.com/gallery/data/3121/IM000157.JPG]]
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| − | Normally a shortram/warm air intake is a better idea if your car sees snow and other wet, inclement weather. A CAI is better suited for track use or for a car which rarely (if ever) sees bad weather. If your car pulls water up in the intake then you'll hydrolock it and if you're lucky you can pull the spark plugs out, crank the engine a few times, reinstall plugs, and be on your way. Lots of times you'll ruin the internals of the engine since water will not compress. The engine parts will bend before water will compress!
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| − | *****
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| − | Bigger is not always better? Your engine will only breathe in what it can, unless it is forced in, turbo, blower, etc. Ramming it in does not produce more power, it still will only breathe what it needs, unless you are cruising at 200+ MPH...
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| − | Cold air intakes are used in applications where the owner/operator feels that the vehicle will produce more power with an outside air charge. Huge misconception, cold air intakes do not produce more power, at least not power that you will feel in the seat of your pants. Most vehicles built today are set up pulling air in from the outside, not from the engine compartment. If you notice that 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. Thus, this is pulling in outside air. It seems that most aftermarket cold air intake kits include the ducting that is smooth, not ribbed or corrilated, this allows for less disruption of the airflow, which in most cases is a heck of a lot more important than the incoming air temperature. High flow air filters in stock intake boxes/housings with smooth ducts works just as well as the high dollar kits that most people invest their money in. Another look, most newer vehicle's air filtration systems flow just as well as the aftermarket competitors, it has been proven. And, some just like the look???
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| − | Then there's the other line of thinking based on physics which states that for each 10* 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. Of course, a tuner would have to compensate for more oxygen by jetting fatter to get the air/fuel mixture back to correct. I don't know much about EFI, being a carburetor guy, but I would think that a computer-controlled system would sense more oxygen and automatically richen the mixture. It just makes sense that if you are pulling in engine bay air which was just pulled through the radiator at 200* and you install a system to pull in (for instance) 100* air from the outside of the car, you have a 100* drop in air temperature which should equate to a 10% increase in power. On a 400 hp motor, this would work out to 40 hp. I would think any tuner in his right mind would jump at the chance to pick up a power increase like that just for running some tubing to the outside. I see these Honda guys all the time who install an aftermarket pipe and then terminate the air filter right behind the radiator in the engine bay. This is obviously monkey-see, monkey-do without any idea of what they're doing. Just money thrown away in my opinion. If they would simply extend the tubing to the outside of the car, they could take advantage of the colder ambient air and make more power.
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| | [[Category:Engine]] | | [[Category:Engine]] |
| | + | [[Category:Carburetors]] |
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