Auto questions: how mufflers work

A guide to the way mufflers function in automoblies, tips on fixing and maintaining.

On all automobiles with gasoline or diesel powered engines, the by-product of internal combustion are exhaust gases, which are expelled from the engine when the exhaust valves open. These exhaust gases then pass through a network of sealed exhaust pipes. On most modern street-driven automobiles, manufacturers have these exhaust pipes lead into a muffler(s) before exiting to the atmosphere usually at a point by the rear of the vehicle.

So why are mufflers used and how do they work?

Due to the high energy created during the combustion process in the engine, exhaust gases when they first enter the exhaust pipes will contain a variety of sound frequencies most of which are not very acoustically pleasing to the ear. Mufflers are therefore used on vehicles as a way to 'muffle' or reduce the sound level of the exhaust gases leaving the engine. They can also be used to tune the exhaust note (like a musical instrument) by canceling out undesirable sounds leaving behind only those which are most pleasant.

The three most common types of mufflers used on the majority of automobiles today are an Absorption muffler, a Diffusion muffler and a Hemholtz chamber.

Absorption Muffler: This design is most commonly used by performance muffler manufacturers as it gives the least resistance to the exhaust gases that pass through. Absorption mufflers work by using a straight perforated tube that's en-cased or wrapped in sound deadening material. In this design, the exhaust gases are able to pass through with almost no resistance while the various frequencies of sounds contained in the gases are absorbed by the material around the perforated tube. Typical materials used for sound deadening are fiberglass, stainless steel mesh and ceramics.

Diffusion Muffler: A diffusion muffler splits the flow of the exhaust gases up into a series of different paths using a series of plates and tubes called baffles. These baffles cause the exhaust to follow a longer path when passing through the muffler. As the exhaust twists its way through these series of tubes and plates, it looses velocity (energy) and in so doing, several sound frequencies are lost and reflected. This in turn tunes the exhaust note that exits the muffler.

Hemholtz Chamber: Also popularly called a Cancellation Muffler or Resonator. This form of muffler derives its name from the German Scientist, Herman Hemholtz, who made several discoveries in the field of acoustics and medicine. The Hemholtz chamber is designed very carefully to be a specific volume and length. As the sounds in the exhaust gases enter on one end, a resonant frequency is established in the chamber that causes all other sounds at that specific frequency to be cancelled out. As this type of muffler only cancels out one frequency in the exhaust, they are rarely used by themselves, but in conjunction with a Diffusion or Absorption Muffler.

Using these three main types of mufflers, the sound frequencies in exhaust gases are tuned, making the final sound that leaves the vehicle be at a desired noise level and quality for both drivers and pedestrians.

How to get a cheap oil change

Looking for a good price on your next oil change? Here are some tried and true tricks that can help you save a few dollars.

Getting an oil change for the car is one of those mindless but necessary tasks that take a chunk of time from a busy schedule every three or four months. The bright spot in an oil change might be the fact that the smart consumer can find ways to save a few dollars on this service, with a little forethought and effort. Here's how.

1. Call ahead. If you have a favorite place you like to take your car, telephone to ask when the next oil change special will be coming up. Assuming that your car will be due within a month and the special will run in three to five weeks, you can afford to make an appointment and wait to save $5 or $10. If you don't have a favorite shop, get out the phonebook and browse the yellow pages, calling the closest or most reputable places. You should be able to locate one that is offering an oil change discount within a few minutes.

2. Watch for signs. On your travels to and from work, taking the kids to school, attending sports events, or going shopping, keep an eye open on all the car repair and maintenance shops that you pass. Chances are one or more of them will feature an oil change special within the space of a few months. Even if you don't need one now, get a feel for how often the discount is offered so you can plan ahead.

3. Buy oil changes in multiples. Some car dealerships or mechanic shops offer a discounted oil change when you buy six or more. If it normally costs $25, the price may be reduced to $20. That can save you $30 or more simply by purchasing several oil changes at the same time. Another advantage is that once you buy several, you're paid up for this service for several months in advance.

4. Contact an auto mechanics school. Vocational high schools or technical schools often teach auto mechanics. Students, supervised by teachers, provide routine maintenance services at lower-than-average prices, mainly to get experience while in training. Find out if there is a school in your area and give it a try next time.

5. Pay a friend or family member to do it. If someone you know can change the oil and replace the filter, along with other needed fluid levels, offer to pay that person instead of a professional shop. As long as you trust the work, you can possibly offer a lower price, say $15 to $20, instead of the full price of $25 to $30 required by most licensed dealers.

6. Barter services. Short on cash? Offer to type a few letters, make a home-cooked meal, or baby-sit an evening or two in exchange for getting your oil changed. Bartering is a hot new trend that encourages people with special skills to exchange their talent for something they don't know how to do. Getting an oil change is a technical skill that might be exchanged for other types of tasks.

Use your creativity and let your fingers do the walking to explore varied options of lowering your oil change fee. Once you figure out a way of getting a lower rate, you may be able to keep it low for months or years, resulting in substantial savings over time. A little bit of effort now can pay off nice dividends later.

Automotive repair: what can cause squeaky brakes?

If your brakes are squeaking, here are some possible causes.

“It kind of sounds like a dying armadillo.” Yep, that’s what the brakes sound like. But what causes this horrific noise?

There are several causes of squeaky brakes, not all of them mean that you have a problem.

Dirt on the brakes – squeaking is a normal reaction of the brake rotor when the pad is new and just wearing in. The pad material is worn away by the braking action, in the process causing brake dirt. This gets on the rotor, or drum, causing the brakes to squeak. In time this will go away as the brakes wear in together.

Outside forces – such as water or oil, from the road or from another system within the car may get on the brake rotor causing it to slip or squeak when in use. Usually, brakes dry quickly, especially if the problem is from outside the car. If the problem continues, be sure to have your car checked for leaks within the car that can be affecting your brakes.

Brake springs – the braking system is made up of a series of springs and hydraulic pistons. A squeaking noise may be coming from one of several springs. This may or may not indicate a problem since springs squeak by nature anyway. This is one case that would warrant having a professional take a look at.

Warning tab – the brake pads are all equipped with a warning tab. This measures the amount of surface you have left on your brake pad and produces a squeal when the pad becomes worn. This is the most common cause of brake noise. This is your first warning to have your brakes checked and the pads replaced. Under normal driving conditions the noise could go on for some time before you cause real damage, but it is best to take it in at your earliest convenience.

Bad Brakes – sometimes, if you ignore the warning tab, or if your car doesn’t have one for one reason or another, you may hear a noise that is ear shattering every time you apply the brake. The metal to metal squeal is a sure indication that you have brake trouble. If you do nothing, you will loose all braking power and are at risk of having an accident. So, you will need to take your car to a mechanic, and he will most likely tell you that you need new rotors, drums, shoes and pads. This is an expensive proposition, and the only way to remedy the problem is to fix it.

Lastly, you may find that the squeaking noise you hear is not from your brakes at all, even though it only happens when you apply the brake. This could be the springs on your car, your shock absorbers, or your trunk lid. These squeaks are easily fixed. Squeaky springs and shocks can be fixed with a lube job. For your trunk lid, try some good all-purpose grease.

Be sure that you have explored all of the other possibilities before you automatically assume that the squeak or squeal you are hearing is from your brakes. It will save you money in the long run.

However, if you do have brake issues, make sure that you have a mechanic take a look at it. Only someone who knows what they are doing should attempt repairs to the brake system.

Customizing your truck: installing pickup truck accessories for truck beds

How to install bed accessories to personalize your truck.

In recent years many people have purchased pickup trucks. But, once you have a truck, you begin to realize you need to personalize it, make it more useful. There are many accessories for your truck bed to do just that. Some of the most popular are Bed Liners, Bed Rails and Bed Covers, as well as cargo nets and the such. Many of these are easy to install in your own driveway with a minimum of tools or knowledge.

Bed Liners

A bed liner will protect the bed of your truck from the scratches and mars that can turn to rust and shorten the life of your truck. Also a bed liner will protect your cargo from slipping around and being damaged.

There are two types of bed liners: Spray on and Drop in.

Generally, the spray on type is best if a professional applies it. This way you are assured of the quality of the product and the installation.

The drop in type, on the other hand, is very easy to install and will last a very long time, even under harsh conditions. These are made of a hard molded plastic. The liners are specifically designed to fit your year and model of truck. It comes in one piece and is attached to your truck by compression fasteners. Begin by placing the liner in the bed of the truck. Then match up the holes along the top of the bed liner with the square holes along the bed of the truck. Place the plastic fasteners in the holes and gently tap them in place. Secure them with the plastic screws to prevent slippage and you’re done.

If you are unable to find a molded bed liner or you just don’t want one for your truck, then you may want to opt for a soft rubber mat. These are like a heavy-duty bath mat and are very durable. To install, just unroll it into the bed of your truck.

Bed Rails

Bed rails are used to tie down items in the back as well as to protect the top of the bed. They are usually attached using the square holes on the side of the bed, with either compression fasteners or bolts and washers. Position the rails along the top of the bed to test the fit. Make sure the attaching points match up with the square holes.

If you are using the compression fasteners, for say the plastic bed rails, then line up the holes and gently tap the fasteners to attach them. Secure them with the plastic screws provided.
If you are using bolts and washers, be sure the rails fit over the square holes because it is always best to keep from drilling too many holes in your truck. The more holes you make, the more opportunities for rust to get in. Place the rails on the top, with the attaching points over the holes. Place the washer inside the square hole from the bottom and line up the bolt holes. Attach the bolts, down from the top. Secure them using the appropriate wrench.

Bed Covers

Bed covers come in two styles, the hard fiberglass trunk lid type or the soft canvas tonneau cover. Both are particularly useful when you want to carry items that you don’t want damaged by the weather in your truck.

Fiberglass Trunk Lid

For the fiberglass trunk lid type of cover, you will need to drill holes in your truck. Review the instructions that accompany your lid for the appropriate size drill bit, proper placement and other important information. Always remember measure twice drill once.

Begin by attaching the hinges at the front of the bed with sheet metal screws, top to bottom. Then place the cover on the hinges, perpendicular to the truck and attach using sheet metal screws. Leave the cover up.

Attach the lifters to the cover first. A press fitting is usually used. Lower the cover. Check the placement of the lifters, inside the truck, usually inside the rail. Mark the screw holes.

Detach the lifters from the cover and return it to its perpendicular position.

Measure the screw holes again, just to make sure, and drill. Attach the lifters at the bottom using sheet metal screws.

Lower the cover and attach the lifters.

Close the cover and verify proper operation of the lock and hinges.

Canvas Tonneau Cover

The soft tonneau covers are a very good choice if you plan to carry large items that require more room, or if a trunk lid type is not available. Many of these are attached with thumbscrews and do not require drilling.

Generally, the soft covers require a frame to provide support for the cover as well as an attaching point. The frame is assembled and attached to the truck in the front and along both sides, with sheet metal screws. Be sure to measure the position of each screw carefully to avoid mistakes. The back of the frame is attached permanently to the cover.

Stretch the cover tight across the frame and attach it using either the heavy-duty Velcro or snaps provided.

Miscellaneous Truck Bed Items

Many people find that they need to tie things down inside their truck. They will use cargo nets, straps, rope, or whatever, so an anchor point would be a great help.

To add anchor points to the bed of your truck, select a large heavy gauge eye bolt with a short shank.

Determine where you want your anchor on the inside of the bed. Then crawl under the truck and verify that this placement will not interfere with electrical, gas, or drive lines. Above all make sure you won’t be drilling into the gas tank.

Drill the appropriate size hole and place the bolt in the hole and the nut under the truck. Use a lock washer to prevent the nut from working loose.

Place as many of these as you would like, the more anchor points, the better.

There are many other accessories that you can add to your truck bed to increase its functionality and beauty. Whatever you choose, make your truck, your own.

Auto questions: how horsepower works

Often times car manufacturers will use terminology we may not completely understand, like horsepower. This article will define what horsepower is and how it works.

The term horsepower is used quite frequently by manufacturers to describe their product lines - whether it is a Chevrolet Corvette with four hundred horsepower or a Ford Mustang with three hundred. Since the muscle car era in the 1960’s, big horsepower outputs in cars have been used to draw buyers into dealerships and increase sales. But what is horsepower?

Horsepower is a term that was invented by James Watt back in the 18th century before cars were around. He came up with this term to measure the amount of energy needed for one horse to haul a load of coal out of a mining pit. The simple definition of horsepower is therefore energy required to lift 550 pounds of coal one foot in the air in one second.

Obviously times have changed, and very few people use their cars to haul coal these days. In simple terms, automotive horsepower is an indication of how able a vehicle will be at moving quickly from one point to another. Horsepower will also be directly related to a vehicle's top speed - a three hundred horsepower Mustang will have a higher top speed than a base Mustang with just two hundred.

The horsepower numbers that manufacturers quote in their marketing material is the estimated amount of power produced at the engine's crankshaft. As a result of internal combustion, the pistons inside an engine move in an up and down motion inside the cylinders. The cylinders are connected to the crankshaft by means of connecting rods and this movement causes the crankshaft to turn. The turning power of the crankshaft is therefore the gross horsepower output of an engine.

Gross horsepower is the measurement taken before any load is placed on an engine. When load is added to an engine, power is sapped by the frictional forces needed to turn the belts and pulleys (that drive the power steering, air conditioning and alternator) as well as the transmission, drive shaft, differential and axles. Net horsepower is therefore the measurement of power taken at the wheels.

The most accurate measure of net horsepower is to place a vehicle on a dynamometer. On this machine, the vehicle's wheels are strapped down onto large metal rollers and the twisting force or torque of the engine measured as the car accelerates through different gears. Torque is the measurement taken by the dynamometer, but this figure is converted into horsepower, as the two values are inter-related. Horsepower is the calculated from torque as follows: (torque x rpm)/ 5252 = horsepower. Net horsepower will always be less than the gross horsepower from an engine.

It is important to note that there will be a difference in net horsepower for two vehicles within the same model line. These differences are caused mainly by the variations within manufacturing tolerances used on the assembly line of a mass-produced car. So while two Corvettes may both be rated from the factory at four hundred horsepower, slight differences during the engine building process could cause one car to make three hundred and fifty horsepower at the wheels while the other makes only three hundred and forty.

Auto cleaning: how to remove stickers from your car window or bumper

Stickers can be safely and cleanly removed from car windows and bumpers using a razor blade scraper and denature alcohol as a solvent. Here's how:

If you put stickers on your car, whether on the glass or the bumper, sooner or later there will come a time when you will want to remove them. Maybe it’s a bumper sticker with a message you know longer identify with, or a political campaign sticker for an election long past. Even if you still like the stickers you put on your car years ago, chances are they are looking pretty bad after years of sun and rain. Even those stickers that go inside the window glass get faded and start deteriorating in the ultra-violent light of the sun. Everyone has seen unsightly stickers like this, and even worse, the partially-peeled off ones that the owners attempted to remove without proper tools and techniques.

Actually, it’s quite simple to remove stickers from a car’s glass, chrome bumpers, or painted surfaces. The first step is to go to the hardware store or a paint store and buy two items: a razor blade scraper with a straight edge and a handle to safely hold it, and a small container of denatured alcohol. These items and perhaps a clean rag or two are all that you need.

Stickers on glass are the easiest to remove. The razor blade scraper will take them right off, and will not scratch the surface of the harder glass. There will probably still be some residue after all traces of the sticker are removed, and that is where the denatured alcohol comes in. Dab some on a rag and use it to scrub away the glue residue. That’s all there is to removing stickers from any kind of glass.

Getting old stickers off of a painted surface is another matter all together. The razor blade scraper will work, but you must be very careful or you will take off a layer of paint as well. The key is to hold the scraper at a low angle and work on small areas of the sticker at a time, starting with the corners. If you can slide the blade carefully between what is left of the sticker and the painted surface, you might be able to peel at least part of it up. Relatively new stickers come off with ease and can sometimes be peeled up in one piece. The older the sticker, the harder it will be to remove. You might have to remove it in tiny bits, alternately scraping with the razor blade and scrubbing with denatured alcohol to loosen the glue. Denatured alcohol is an excellent all-around solvent that is mild enough not to damage paint. Stronger solvents such as acetone would work faster, and are okay on glass, but might dull the paint finish permanently. Some solvents might even remove paint and ruin the finish. So no matter how resistant the sticker and residue are to removal, don’t be tempted to try anything but denatured alcohol.

Once all stickers and their residue have been removed, wash the car with soap and water. The alcohol should have evaporated by now anyway, but it doesn’t hurt to wash it off. Given the difficulty of removing really old stickers from a painted surface, you might want to limit future stickers to the glass or replace them after a year or so before they start to deteriorate.

Auto questions: how gear ratios work

A gear ratio allows engines to operate optimally at different speeds. Detail about the differences in gear ratios and their parts and uses.

Whether your car uses an automatic or manual transmission, manufacturers have designed a specific set of varying gear ratios in the transmission. Some gears are better suited when moving off from a stop light or up a steep hill, while others work best when cruising along the highway. So, why are different gear ratios needed in cars and how do they work?

The majority of modern transmissions are designed with between four to six different gear ratios. These gear ratios are specifically chosen by the manufacturer for the particular engine or style of engine that your car or truck uses.

Despite the amazing power and torque that most modern engines produce, the internal pistons and moving parts will reach their maximum speeds at around five to seven thousand revolutions per minute (rpms). While this range of engine speed may seem very wide and impressive, in reality, it is a narrow range that wouldn’t allow our engines to be very useful in everyday driving without the help of gears of varying ratios.

Without the different gear ratios in our transmissions, engines would operate our cars with one gear only, which would have to be low enough to move the vehicle off from rest, yet high enough to allow cruising on the highway. If you put the shifter on a car in first gear, the car would move quickly away from rest, but at around thirty miles an hour, the engine would be screaming along near redline (manufacturer’s maximum ‘safe’ engine speed). Similarly, if the same shifter was put into a taller gear such as fourth, the engine would die and be unable to move the car off from a dead stop. However, if the car was already moving, the engine would probably start to come to life around thirty miles and hour, while highway cruising at sixty miles an hour would be at comfortable engine speed. While some motorized vehicles utilize one gear such as a golf cart or motorized scooter), their top speeds are not very high and their utility is generally quite limited.

This is where gears of varying ratios come into the picture.

The main purpose of a gear is to either magnify or reduce the speed of the output shaft (or crankshaft) from an engine. A shorter gear such as first or second on most transmissions, magnify our engine’s torque (twisting force) to the wheels by spinning slower than the engine’s output shaft. In this way, the engine is ‘assisted’ by the gears in moving a heavy object (our car) up a steep hill or away from a dead stop. Taller gears, such as those used in fourth or fifth gears, reduce the engine’s torque output to the wheels by spinning faster than the engine’s output shaft. This allows the car to move faster while the engine works at a leisurely pace – which in turn improves fuel consumption and driving quality (as engine noise will be low).

Our engines therefore use the different gear ratios in our transmissions to better utilize its power in all situations, improve both fuel economy and driving quality, as well as to keep the engine moving at a comfortable pace regardless of the vehicle’s speed.

Auto questions: how automatic transmissions work

The automatic transmission has gained popularity in recent years because of the ease of its use. Information on functionality and maintenance.

The automatic transmission is by far the most common transmission found on the modern automobile, due to its universal ability to be used by all drivers, ease of operation, along with its inherent strength and long-term durability. Unlike a manual transmission, an automatic does away with the clutch pedal allowing drivers to move along seamlessly in heavy traffic without stalling their cars or having a tired left foot (used to operate the clutch pedal in a manual car). So how does an automatic transmission work?

The key to the 'clutch-less' automatic transmission is the torque converter. The torque converter essentially replaces the clutch and multiplies the turning power of the engine. The torque converter has no physical connection to the engine but is turned by means of process known as hydraulic coupling. The transmission shaft that runs through the torque converter fits around the crankshaft coming from the engine. These shafts sit next to each other with the slightest gap in-between. Transmission fluid fills the gap, and as the engine turns the main crankshaft, the transmission shaft (including torque converter) is turned as transmission fluid is not easily compressed. This is known as hydraulic coupling.

The torque converter looks similar to an oversized bagel, and contains three main components: an impeller (pump), stator (guiding wheel) and a turbine. The torque converter is filled with transmission fluid and by similar hydraulic coupling process, the impeller and turbine spin in tandem to each other. As they spin, the transmission fluid is directed towards the outer edges by centrifugal force, where it is re-directed by the stator towards the turbine. In this way, there is a constant flow of fluid which works to multiply the power of the engine. Modern torque converters will also have a lock-up feature that activates at speeds above forty miles an hour to improve gas mileage and the efficiency of the system. This lock-up occurs when a metal pin physically connects the impeller to the turbine. When your speed falls below forty miles an hour, the pin is released again.

The crankshaft and transmission shaft spin in harmony with each other. The transmission shaft runs trough the length of the transmission past a planetary gearset (sometimes multiple gearsets in newer automatics). The planetary gearset will include three main components: a sun gear, ring gears and drums, along with a planet carrier. Similar to our solar system, the planetary gears revolve around the central sun gear using the planet carrier. The planetary gears are of different sizes allowing different gear ratios to be used as the transmission moves through the gears (1st - 4th gears).

When in neutral, only the transmission shaft will turn. As first gear is engaged, the planetary gear corresponding to first, rotates around the sun gear on the planet carrier and locks onto the transmission shaft. This physical 'locking' engages the gear allowing the car to move forward. When the next gear is needed, the planetary gear for first is disengaged and the planetary gear for second is rotated onto the transmission shaft. During this shift into second, the central sun gear is held in place by an intermediate band. This flexible metal band (also call the brake band), fits around the outside of the clutch housing and has friction material around the inside. During shifts it loosens to release gears and tightens back down to 'lock' gears in place on the transmission shaft.

This is in essence how the modern automatic transmission works.

Turbocharger kit basics

The five main components which all safely increase the power your automobile is making. A brief look at this technology.

The turbocharger is easily one of the most powerful and efficient performance parts that can be added to a car as it can raise the power output of an engine by over 40%! While some cars come with a turbo straight from the factory (e.g. Dodge Neon SRT-4, Mitsubishi Lancer Evolution, Audi A4 1.8T and the Subaru WRX STI), most cars are lacking one, which creates a big demand for turbocharger kits in the automotive aftermarket industry. So what’s included in the basic turbocharger conversion kit available on the market?

There are five main components that are included in most aftermarket turbocharger kits:

1) Turbocharger

2) Exhaust manifold

3) Wastegate & Blow-off valve

4) Oil supply

5) Intercooler

Turbocharger: The turbocharger or turbo is the heart of any aftermarket turbocharger kit. In basic terms, a turbo works by compressing the air contained in the exhaust gases, that’s expelled from an engine after combustion. The compressed air is then directed back into the intake pipes to the engine. This compressed, dense air allows more power to be created during the combustion process (when a spark ignites a mixture of air and fuel) which results in the engine producing more power. Turbos come in varying sizes, and generally speaking, the larger the size of the turbo, the greater its flow potential or ability to make power. One downside of large turbochargers is that the spooling time of its turbine/compressor wheels will take longer to reach peak speed, which causes a noticeable lag during acceleration before full power is generated!

Exhaust Manifold: The exhaust manifold is used to direct exhaust gases away from an engine after combustion. In a turbocharged engine, these gases can’t be expelled directly into the exhaust pipes as this exhaust flow is used to power the turbocharger. As a result, a modified exhaust manifold is needed to direct these gases towards the turbocharger. Most aftermarket kits will include one as this is an essential component in the turbocharger kit.

Wastegate & Blow-off Valve: The wastegate and blow-off valve are used to regulate the pressure in a turbocharged system. In simple terms the wastegate regulates the pressure in the exhaust manifold leading up to the turbo, while the blow-off valve regulates the pressure of the compressed air that leaves the turbo directed back to the intake of the engine.

Most wastegates on aftermarket turbocharger kits are built into the turbo specific exhaust manifold and directs exhaust gases away from the turbocharger housing if too much pressure is built up in the manifold. The wastegate is controlled by a vacuum actuator that constantly monitors the pressure in the exhaust manifold and opens the wastegate if pressure surpasses a pre-set value.

A blow-off valve is used to control the pressure or ‘boost levels’ that are being directed into the engine as well as to ensure that the airflow doesn’t reverse direction. As the revolutions per minute or ‘rpms’ rise in an engine, the exhaust flow directed towards the turbocharger housing will increase causing the turbine wheels to spin faster and faster (some turbos spin up to 150,000 rpms). The faster the turbine wheels spin, the more the gases are compressed, resulting in more boost or pressurized air being directed back into the engine. While higher boost generates more power, most engines have a maximum boost level that they can utilize safely. In situations where boost levels exceed a pre-set value, a valve in the blow-off valve opens releasing the excess pressure out of the system. The second purpose of the blow-off valve is to ensure that the airflow in the system moves in one direction. In situations where throttle input is quickly reduced – such as during transmission shifts – it is possible for the airflow to become reversed towards a region of lower pressure (e.g. the turbocharger housing). Due to this risk, the blow-off valve is programmed to open during these situations.

Oil Supply: This is a crucial but simple part of the turbocharger kit as all turbos will need an oil supply to lubricate moving parts and take heat away from the turbine housing. Most aftermarket turbo kits will include both an oil supply and return line that are plumbed into the engine’s oil system, at specific points.

Intercooler – Some inexpensive turbocharger kits will not include an intercooler but this is a vital component needed in order to extract as much power as possible from turbocharging. The one downside of compressing any gas very quickly is heat. The hotter a gas the more it expands decreasing the density of its molecules. Cooler, denser air is therefore needed to enable an engine to produce as much power as possible. Without an intercooler, turbocharged systems can produce compressed air that’s over 200 degrees Fahrenheit in temperature. This is where the intercooler comes in, and it is used to cool the compressed gases before directing them into the engine. Intercoolers are generally located in regions that receive an unobstructed airflow such as the front of a car. The most efficient intercoolers can reduce the temperature of the compressed air to within a few degrees of the outside ambient air temperature.

Auto questions: how fuel processors work

A catalyst and heat are used to liberate hydrogen from natural gas or liquid fuel, to react with oxygen and produce electricity.

Hydrogen and oxygen can combine to produce electric power in fuel cells. Such electric power can replace internal combustion engines for transport and other important everyday applications. This technology is limited by the difficulty in storing and transporting hydrogen. It has relatively low energy per unit volume, so one would need to carry huge quantities of gas around to drive a car for even a small distance. Hydrogen can be cooled in to a liquid state and is somewhat more energy efficient for volume in this state. However there is no easy way to cool hydrogen and keep it in a liquid state at the individual consumer level. Fuel processors are used to liberate hydrogen from natural gases such as propane, methanol, ethanol and natural gas that are denser than hydrogen itself. Fuel processors may also liberate hydrogen from a liquid fuel such as gasoline. This makes it more practical to use fuel cells.

A steam reformer is one kind of fuel processor. Steam reformers work on either methanol or on natural gas. Liquid methanol and water are converted in to their gaseous states using heat and a catalyst. The methanol liberates hydrogen as it comes in contact with the catalyst. This process also liberates a noxious gas, carbon monoxide. Carbon monoxide is a pollutant. However, oxygen liberated from water vapor, converts most of the carbon monoxide in to carbon dioxide. This controls the pollution impact of a fuel processor. A fuel processor can liberate hydrogen from methane in natural gas. The carbon monoxide that is not oxidized can be burnt to reduce if not eliminate dangerous emission.

The volume of hydrogen generated by a fuel processor can be controlled by the rate of flow of methane or natural gas. This volume of hydrogen determines the amount of electricity generated, which in turns determines the amount of torque produced by an electric motor in combination with an inverter. This torque can be used for motion or any other application as in the case of other forms of energy. Voltage is produced as direct current. A fuel cell may be fixed at one place to generate electric power or it may be designed to be transportable as for example, in the form of a power source for a vehicle.

Proton Exchange Membranes, Alkaline, Phosphoric acid, Solid oxide and molten carbonate are other types of fuel cells. They all rely on hydrogen and oxygen to produce electricity. Fuel processors hold the key to overcoming the problems of storing large quantities of hydrogen gas and of keeping large volumes of hydrogen in liquid form.

Fuel processors produce some amounts of carbon dioxide, which may be a considered to be a pollutant for the ozone layer of the atmosphere. Fuel processors are also relatively inefficient in producing energy from fuel. Researchers are working on finding solutions to these drawbacks of fuel processors. However they remain a useful alternative to internal combustion of fossil fuels. Fuel cells can also replace batteries used to power electric devices and turbines that produce industrial amounts of power.

Auto questions: how odometers work

You can see the numbers on your vehicle's odometer click over, but do you know what makes that happen? Find out how it measures the distance traveled and keeps track of the total number of miles an automobile has traveled.

An odometer can be defined as a "device that measures and keeps track of the distance traveled by a moving vehicle." The idea of the odometer, or the measuring of distance traveled, originally came from the famed inventor named Benjamin Franklin. When he was a postmaster, one of his jobs was to map out mail delivery routes. So, he took his horse and carriage out in order to figure out the best way to plan the different routes. Right away he realized that he needed a way to measure the distance of the carriageways so he could find the shortest ones. The device Franklin invented worked by counting the revolutions of the axles of his carriage.

Today, odometers can be found on every car, truck, van, and motorcycle manufactured today. Many bicycles have odometers mounted on them too. It keeps track of the total number of miles a vehicle has traveled. This is especially important because every vehicle title has a space where the current owner must write in the total numbers of miles the vehicle he/she is selling has on it. Turning back the odometer, or writing in a lower number on the title is fraud, and is punishable by United States law.

So, how does a modern-day odometer work? The odometer is located on the dashboard of a vehicle. It usually is located near the speedometer, and it also shares the same flexible cable if they run mechanically. The only part of the odometer you can see are the six or seven drums. They are all numbered from zero to nine. When the tires of the vehicle turn around, the cable causes the connected plastic gears in the back of the odometer to turn in succession. As each mile is traveled by the vehicle, the gears turn enough so that one (or more) of the drums clicks over to the next higher number. Usually, if the vehicle has traveled one mile, the next to the last drum to the far right clicks up a number. If, however, the vehicle already has an odometer reading of eighty-nine thousand, nine hundred and ninety-nine miles, when another mile is driven, all five of the drums will click over to the next number. This, of course, will make the new odometer reading ninety-thousand miles.

The drum that is the farthest to the right is called the "tenths" counter. It adds up every tenth of a mile that a vehicle travels. When it reaches ten tenths of a mile, of course, it clicks back to zero, and the number in the next column clicks up a number higher.

There is a second type of odometer on a vehicle that is called a "trip odometer." Unlike a mileage odometer, this odometer can be readily set back to zero with the simple push of a button. It's not for measuring and keeping track of total miles put on a vehicle. Its purpose, just like its name implies, is to simply keep track of the number of miles that a certain trip from point A to point B used.

This type of odometer can be especially useful for checking to see how many miles per gallon you're getting on a tank of gasoline used by a vehicle. You can fill the gasoline tank up in your vehicle, reset the trip odometer, and drive the vehicle until it almost runs out of gasoline. Or, you can fill up the tank, reset the trip odometer, and watch for when you have driven enough to use up, let's say, a quarter of a tank of gasoline. If the tank holds twenty gallons, and you use a quarter of a tank, that means you have used five gallons of gasoline. If you have driven one hundred and fifty miles, according to the trip odometer, that means that your vehicle got thirty miles per gallon of gasoline.

Auto questions: how diesel two-stroke engines work

Hot compressed air combusts with injected diesel in a closed cylinder to drive a piston and produce extraordinary torque for displacement volume.

The principle of a 2-stroke diesel engine is to ignite a combination of compressed air and fuel, to drive a piston that in turn rotates a crankshaft. Valves control the intake of air as well as the outlet of exhaust. A turbocharger compresses air before it is fed in to the cylinder. An injector sprays diesel on to the compressed air. Combustion results in the motion of the piston in a massive power stroke. Each cylinder has between 2 and 4 exhaust valves at the top. All the exhaust valves open at the same time. The piston in each cylinder opens the air intake ports as it completes each downward stroke. The air intake drives out the remaining exhaust and the outlet valves close to allow the piston to move upwards with the force of the compressed air.

2 stroke engines work better on diesel because fuel combustion is more efficient than with a petrol-based system. A diesel 2-stroke engine is able to accommodate more air in the cylinder as compared to a comparable displacement in a 4- stroke petrol engine. This produces a relatively high amount of power as compared to a petrol engine of comparable size. 2-stroke diesel engines are used in heavy equipment and machinery such as locomotives, ships and generators. A 2-stroke diesel locomotive engine will typically have 16 cylinders, each with a displacement of over 600 cubic inches. Such an engine may produce more than 4 thousand horsepower. 2-stroke diesel engines are very reliable and relatively fuel-efficient as well. They have simple design but offer rugged and extremely powerful performance. These engines have relatively few parts and are therefore comparatively easy to maintain.

The turbocharger is at the heart of a 2-stroke diesel engine, for it is primarily responsible for the relatively enormous amount of power the engine can produce for its weight and size. The turbocharger gets a greater volume of air into the cylinder. This increased air volume with additional diesel from the injection system makes for a more potent explosion inside each cylinder. The torque generated is consequently very high compared to a petrol engine with the same displacement. This system is especially productive in high altitudes where the air becomes rare.

The volume of air available for combustion in the cylinder reduces at high altitudes. This effect is partially mitigated in an engine with a turbocharger. A turbocharger in a 2-stroke diesel engine uses hot exhaust to drive a turbine. The latter is connected to an air pump. This system produces a differential pressure that results in a great gush of hot air entering the cylinder. A heat exchange system cools the hot exhaust before it is packed in to the cylinder. More air can be accommodated as a result of such cooling. This ensures more efficient and powerful combustion when diesel is introduced in the chamber. A supercharger may also perform the role of a turbocharger. A supercharger runs on a belt rather than on exhaust gas. The principle of accommodating more air in the cylinder remains the same whether a turbocharger or a supercharger is used.

Auto safety questions: how red-light cameras work

In response to the growing numbers of traffic accidents at intersections, red light cameras have been installed to catch violators.

It is a scenario drivers are becoming all too familiar with: they think they have gotten away with running a red light only to receive a ticket in the mail months later. Police officers are not available to patrol every intersection anymore, both because there are too few of them and because they are needed on high-priority calls. Still, it is necessary for the police department to keep an eye on the traffic situation at all times. Too many accidents occur every year because motorist run red lights, speed, and ignore other traffic laws. For this reason, many jurisdictions have installed red light traffic cameras to catch offenders when they think nobody is watching. If you have ever been at the receiving end of a ticket because of these so-called "camera cops," it can be helpful to understand how they work.

One day Joe Driver receives an upsetting piece of mail. There is a note about a traffic violation that occurred weeks or months ago along with a fine and a picture of his car at the time of the incident. He has been caught in the act of performing a driving faux pas, even though he never saw a cop. It occurs to Joe that that box he noticed on the traffic light pole was not the crosswalk sign for which he had taken it. Instead, it was part of a camera designed to keep an eye on the intersection. Still, he wonders how this machine connected him to the picture. Was someone watching the camera at the far-off police station just waiting for him to drive by? No, the technology used in these cameras is actually far more sophisticated than that. Here is what happened the day that Joe ran the red light.

There is a traffic camera mounted at the intersection that Joe passes on his way home. Since he is running late and there is no one else there, he decides not to stop when he sees that the light is red. Instead, he rolls through at 35 mph. Buried in the asphalt of his lane, there are two loops of wires through which electricity run called induction loop triggers. Every time the traffic light to which these wire are connected turns red, the camera and computer in the system are activated. One loop in the set detects when Joe's car approaches the intersection, while the other one can tell if he crosses the stop line. This happens because the metal of Joe's car disrupts the normal electromagnetic levels of the charged wires. Any shift in the levels serves as a trigger, hence their name. Once triggered, the wires send messages to the traffic computer.

The computer is manned when Joe's car crosses the first trigger, at which point it waits to see if he will cross the second while the light is red. Once this happens, it sends a message to the camera to turn on. The camera, which is generally digital, although older models use film cameras, takes a picture just as Joe crosses the stop line and rolls into the intersection. This picture captures the car's license plate number. After a short pause, the camera takes a second picture, which catches Joe inside the intersection. Beyond providing double proof of the traffic violation, this second picture is also used to gauge Joe's driving speed. The computer calculates how far the car has traveled in between shots (which occur at set times) to judge if he was speeding on top of running a red light. The computer adds the day and time of the violation, as well as where he was and how fast he was going. Finally, it notes how much time passed between the light turning red and the car's entrance into the intersection.

Each violation photo is sent to the computer's memory bank, where it is stored until collection. The police station accesses the photos and has only to match license plates to their citizens. They then print out a ticket and a copy of the photos, which are mailed to the car's owner. If the state in which the violation occurs does not hold the owner responsible if another driver committed the crime, the owner will still receive the ticket. However, the camera will also take a picture of the front end of the car to identify who was at the wheel. In this way, the owner can prove his innocence in court if necessary. Police departments are very fond of these cameras because they provide indisputable proof of wrongdoing and work all day every day. Drivers, however, are not so fond of what some consider a sneaky way to catch people. They argue that there is no room for leniency, as a camera cannot give a warning under special circumstances. Like any other ticket, these violations can be disputed in court, but most people simply mail in the fee they have been charged. This is another perk for law enforcement, as they can catch everyone who runs red lights. This generates more money for the department on top of protecting thousands of lives every year.

In conclusion, the red light traffic camera offers a deterrent to reckless drivers, reminding them that someone -- or something -- is always watching them on the road. New designs are being implemented in different cities that use lasers, radars, and even video sensors in exchange for buried trigger wires, which require tearing up portions of the road. They cost little to maintain and are very reliable, all of which are important factors in a time when police departments are undermanned and under-funded. It is law enforcement's hope that the widespread use of these cameras will curb the rising numbers of accidents and deaths that result from running traffic lights.

Auto questions: how catalytic converters work

The catalytic converter plays a major role in automobile emission reduction. A guide to function, repair and parts.

If you own a car that’s 10 years old or older and you live in an area that requires annual testing for automotive emissions, you may have already heard the dreaded words “You need a new catalytic converter”. If you haven’t, you soon will. If you’re like most drivers, you may be vaguely aware that your car has a catalytic converter but you have only a vague notion of its function. Hopefully this article will help you understand a bit more about this key component of your vehicle.

In the 1970’s when we first became concerned about the effect of automobile exhaust on air quality, a great deal of research was done to define the problem. If cars were perfect and burned their fuel completely, the exhaust would consist of carbon dioxide (CO2) and water (H2O). Since nothing is perfect, least of all cars, the analysis of actual exhaust gasses revealed the presence of several troublesome components. First, it was found that a portion of the gasoline that entered the engine was not completely burned and escaped into the exhaust. This component was labeled as “hydrocarbons (HC)”. Another result of this incomplete burning was “carbon monoxide (CO)”. The third major component was labeled “nitrogen oxides (NOx)”. Air is actually composed of over 70% nitrogen which when subjected to the high temperatures and pressures inside an automotive engine combines with some of the oxygen in the air to form these compounds. The exhaust has other components but these are the main elements that the automotive industry focused on.

Because most of these components were created as a result of incomplete burning of the gasoline, a lot of the early work to reduce them was centered on improving the mixing and burning of the air and fuel. Manufacturers experimented with engine and fuel system designs and modified the proportions of fuel to air. Fuel injections systems began to replace carburetors in order to more precisely control the flow of fuel and electronics became a factor in engine control. All of these efforts had some degree of success but as air quality standards became ever more restrictive it was evident that a new approach was needed. It was at this point that the concept of the catalytic converter began to be seriously considered.

What is a catalyst? Many years ago, chemists discovered that there were materials present in certain chemical reactions that were not changed by the reaction. In other words, these materials were the same after the reaction as they were before it. Even more surprising, the reaction would not occur if these materials were not present. Somehow they enabled the reaction to occur without taking part in it. They called these materials catalysts and they are widely used in industry. The materials are often rare earth metals like palladium and platinum which are very expensive. But luckily the amount needed for use as a catalyst is small and since the catalyst is not changed by the reaction it can be used over and over.

As it turns out, experiments showed that passing exhaust gasses over a catalyst of a certain composition will cause the pollutants in the exhaust to be completely burned and the result is water (H2O) and carbon dioxide (CO2). The challenge was to create a catalyst that could be attached to the car and survive for 50,000 or so miles of driving. The catalytic converter is the answer to that challenge. A catalytic converter starts with a ceramic honeycomb about 3 inches by 5 inches by 8 inches. Some are larger and some are smaller. This honeycomb is coated inside and out with a very thin layer of catalyst material. It is them place inside a metal container with a hole where the exhaust gasses enter and one where they exit. The unit is then placed in the exhaust system near the engine. In order for the converter to operate properly, several conditions must be met.

First, the exhaust gasses must be at or above a certain temperature. This is why the converter is placed close to the engine. Second, there must be a certain minimum surface area of catalyst for the gasses to come in contact with. This is the reason for the honeycomb design. It provides a large surface area in a small space. Third, the ratio of exhaust gas to air must be maintained within very rigid limits. If these limits are not observed, the converter will not function and could even be damaged. These limits are maintained by placing a special sensor in the exhaust just before the converter. This sensor detects variations in the ratio and signals the fuel supply system to increase or decrease the amount of fuel being supplied to the engine. Lastly, the converter has to survive its own operating temperature of 1500 degrees F or more, exposure to water, mud, snow and road debris and continue operating for a government mandated period of 50,000 miles or more. The catalytic converter is an amazing device that allows us to enjoy the freedom of our automobiles while helping keep our air clean.

Auto questions: how car computers work

Today's cars make intense use of modern electronics. Here's a primer on how the computer in your automobile works.

The computer in your car is actually very similar in function to the computer on your desktop. The difference is that while your desktop PC is a multifunction machine capable of word processing, Internet connection, etc., the automobile computer is specialized to perform only one very complicated function, controlling your car.

The capabilities of the car computer vary widely depending on the make and model of automobile. In some cars, the computer may control only the fuel and ignition systems while in others it can also control the temperature in the passenger compartment, the instrument panel and even the braking system. Let’s look at exactly how the computer performs some of these functions.

Computers first made their mark in the auto industry in the mid-‘70’s when engineers were seeking ways to control automobile exhaust emissions. They realized that they needed a way to more precisely control the introduction of fuel into the engine and began experimenting with electronic fuel injection. An automobile must operate over a wide range of conditions from idling at the stop light to full throttle passing acceleration on the highway. Controlling the fuel flow over such a huge variation in requirements seemed a tailor made job for a computer. Before fuel injection, cars used carburetors to control the flow of gasoline. Changing the characteristics of a carburetor required actual physical changes to the design. Often making a change to improve performance in one area would have and undesirable effect on another area. In a computer controlled system, changing the operation required only a change in program rather than a mechanical change. Several years of experimentation and improvement led to reliable inexpensive computer controlled fuel injections systems that significantly improved automobile performance. Their success with this effort along with the increase in speed and power of computers encouraged them to try controlling other auto functions in a similar manner.

It turns out that having more precise control of the ignition system also led to better performance and control of exhaust emissions. When coupled with high energy ignitions and spark plugs, they also achieved significant decreases in required maintenance. As with home computers, the automobile computer continued to increase in power and speed and decrease in price placing more computer power at the disposal of the engineers. They responded by developing antilock braking systems, digital instrumentation, automatic climate control and a host of other computer controlled features.

But this revolution would not have been possible without advances in many other fields. In order to perform these control functions, the computer must receive and output information. On your home computer, you input information via your mouse and keyboard and receive output from a printer. An automobile computer receives its input from sensors and sends out signals that control fuel injectors, spark coils or digital speedometers. As computers were developing there was a simultaneous development in sensors that greatly improved the quality and reliability of the information input to the computer. As an example, to control a fuel injection system the computer must know how much air is entering the engine at any particular time. This can either be measured directly by an air flow sensor or calculated from measurements of such things as air temperature, pressure and engine speed. In either case, these pieces of information are supplied by sensors attached to the engine and connected to the computer. The computer then calculates the proper signals to send to the fuel injectors that actually allow fuel to enter the engine. Computer controlled ignition systems require sensors that measure the engine speed and piston position. The computer then calculates the precise instance at which to send a signal to fire the spark plug and ignite the gasoline. Sensors mounted on each wheel send signals to the antilock braking system. If the computer detects that one wheel is beginning to move more slowly than the rest (in other words, it’s skidding), the computer signals the braking system to release pressure on that wheel to stop the skid. It does this on each wheel separately and simultaneously and it obviously does it much faster than the driver could.

Every function that the computer performs is controlled by a program. These programs are written by the engineers who design the systems. Unlike the programs on your personal computer which are stored on disk drives, these programs are stored in special electronic circuits called ROMs (Read Only Memory). This provides for instant startup and high reliability.
When the use of computers in cars was first being considered, computer manufacturers were very confident of success. After all, they had sent computers to the moon. A series of humiliating failures soon convinced them that this project wasn’t as easy as it seems. The automobile computer must operate reliably from -40 degrees to 140 degrees. It must be impervious to water, oil, dirt and a variety of other contaminants. It must not fail and leave the car without brakes or lights or any other safety related items. It must not malfunction when subjected to electrical interference from radios or ignition systems and it must start immediately and operate continuously and reliably under all conditions. These are just a few of the issues that automobile electronics designers faced. Despite these huge challenges, the computer and automobile engineers persisted and today’s cars are safer, cleaner and more reliable than they’ve ever been. And the use of automobile computers is behind most of these advances.

Auto safety questions: how power brakes work

The advent of power brakes was a milestone in automotive development. A guide to funcionality, repair, parts.

If you’ve ever driven a vintage car from the early 1950’s or before, you realize what an advance the development of power brakes was. If you were a member of the driving public during the changeover, you probably recall the adjustments that were necessary in driving techniques. The early systems were somewhat touchy and led to many undesired screeching stops but today’s braking systems provide smooth reliable and safe stopping power. And with the advent of anti-skid braking systems, automobile manufacturers have taken another big step in automotive safety.

The basics of the automotive braking system are the same regardless of whether you are considering power or non-power, disc or drum so let’s consider that first. When you push on the brake pedal, you are forcing a plunger into a cylinder (called the master cylinder) filled with brake fluid. Brake fluid is an oily liquid that has features of corrosion and temperature resistance that make it especially suitable for brake systems. As the plunger goes into the cylinder, fluid is forced out into metal tubes called brake lines. These lines run from the master cylinder which is usually mounted just behind the brake pedal to each of the wheels. At the wheel, the line connects to another cylinder (called the slave cylinder). As the fluid enters the slave cylinder, its plunger is forced outward and presses the brake pad or shoe against the spinning wheel. The friction between the shoe and wheel cause the wheel to slow down. By adjusting the relative sizes of the master and slave cylinder pistons, you can magnify somewhat the force applied to the master cylinder. This effect is however limited by physical constraints such as where the cylinders have to be placed.

The idea behind power brakes was to find a way to magnify even more the pressure applied to the master cylinder so that even relatively weak drivers could apply the maximum force and stop as quickly as possible. They decided to use a variation of the same principle that was already in use in the master and slave cylinder arrangement. Suppose I have a hollow sphere and stretched across the middle of the inside of the sphere is a flexible wall called a diaphragm. If I start to remove air from one side of the sphere and allow air to enter the other side, the diaphragm will bend toward the side with less air (lower pressure). Now if I attach a rod to the center of the diaphragm on the low pressure side and then attach that rod to my master cylinder plunger, the rod will push on the plunger and apply the brakes. How hard it pushes depends on how big the diaphragm is and how much air is removed. So the first step in developing power brakes was to attach a flattened sphere with a large diaphragm inside to the master cylinder.

The next question was how to remove air from the sphere. As it turns out, a running engine is constantly sucking in air to mix with gasoline so it was an easy task to attach a small hose from the engine to the sphere and let the engine take air from it. Of course we only wanted it to be connected when we applied the brakes so a valve was needed. Now we attach our brake pedal to the other side of the sphere so that when the pedal is pushed it pushes on the other side of the diaphragm and our system is complete.

So when you step on your power brake pedal, two things happen. The brake pedal pushes on the high pressure side of the diaphragm and therefore on the rod attached to the low pressure side and then on to the master cylinder. This is important because if the power booster unit (this is the official name of the sphere) fails, we still have manual brakes. At the same time, the movement of the brake pedal opens the valve that allows the engine to remove air from the low pressure side and the diaphragm moves and applies even more pressure to the master cylinder and therefore the brakes. So the pressure of our foot is magnified and the brakes are applied much harder for extra stopping power. There is much engineering work involved in finding just the right size diaphragm, making sure the valve opens properly (not too fast and not too slow) and matching all the other components for smooth reliable operation but the basics remain the same.

Now another problem arose. Cars stop fastest when their wheels do not skid. The shortest stopping distance is achieved when the brakes are applied such that the wheels are almost but not quite skidding. Now that power assist gave anyone the ability to apply maximum force to the brakes, skids became even more likely. So the next step was anti-skid braking systems. When computers became a viable component of automobile systems, sensors were mounted on each wheel. These sensors monitored the movement of the wheels and when the computer detected that a wheel had stopped spinning but the car was still moving, it released the brake on that wheel until the skid stopped and then reapplied the brake. This happens much faster than a driver could react and means that the car will stop in the shortest possible distance.
Brake systems today are typically broken into two separate systems so that if one fails the other can still stop the car. Combined with anti-skid brake systems, this provides a level of safety and reliability that was unheard of even 10 years ago.