The Basics of Car Cooling Systems (Cooling System 2)

Inside your car's engine, fuel is constantly burning. A lot of the heat from this combustion goes right out the exhaust system, but some of it soaks into the engine, heating it up. The engine runs best when its coolant is about 200 degrees Fahrenheit (93 degrees Celsius). At this temperature:

• The combustion chamber is hot enough to completely vaporize the fuel, providing better combustion and reducing emissions.
• The oil used to lubricate the engine has a lower viscosity (it is thinner), so the engine parts move more freely and the engine wastes less power moving its own components around.
• Metal parts wear less.

There are two types of cooling systems found on cars: liquid-cooled and air-cooled.

Liquid Cooling

The cooling system on liquid-cooled cars circulates a fluid through pipes and passageways in the engine. As this liquid passes through the hot engine it absorbs heat, cooling the engine. After the fluid leaves the engine, it passes through a heat exchanger, or radiator, which transfers the heat from the fluid to the air blowing through the exchanger.

Air Cooling

Some older cars, and very few modern cars, are air-cooled. Instead of circulating fluid through the engine, the engine block is covered in aluminum fins that conduct the heat away from the cylinder. A powerful fan forces air over these fins, which cools the engine by transferring the heat to the air.

source: http://auto.howstuffworks.com

How Car Cooling Systems Work (Cooling System 1)

Although gasoline engines have improved a lot, they are still not very efficient at turning chemical energy into mechanical power. Most of the energy in the gasoline (perhaps 7 0%) is converted into heat, and it is the job of the cooling system to take care of that heat. In fact, the cooling system on a car driving down the freeway dissipates enough heat to heat two average-sized houses! The primary job of the cooling system is to keep the engine from overheating by transferring this heat to the air, but the cooling system also has several other important jobs.

The engine in your car runs best at a fairly high temperature. When the engine is cold, components wear out faster, and the engine is less efficient and emits more pollution. So another important job of the cooling system is to allow the engine to heat up as quickly as possible, and then to keep the engine at a constant temperature.

source: http://auto.howstuffworks.com

Car Cooling System

An efficient cooling system is very essential in order to protect the engine from overheating. Use good quality coolant for your car engine. The coolant level should be checked at least once a fortnight and preferably at more frequent intervals during summers.

Special attention should be given to the pressure cap over the radiator. When the coolant reaches very high temperature, it forces its way through a valve in the pressure cap and the overflow is then collected into coolant reservoir. When the engine is cool, the vacuum created in the radiator draws the overflow back. If the pressure cap is defective, the coolant evaporates through the pressure cap when it reaches high temperature, instead of flowing into the coolant reservoir. This reduces the level of coolant and can harm the engine.

Cooling system hoses should be checked regularly, especially before summer. Any hose that is cracked, and feels hard or spongy when squeezed should be replaced immediately. Ensure that the fan belt is working properly since it plays a vital part in cooling the engine. Get the cooling system serviced at the onset of the summer.

Oil Change Tech Tips

• Drain the oil while it is hot. Contaminants will be in suspension and drain more easily from the engine.

• Always replace the filter when changing the oil

• Wipe some oil on the filter gasket so the seal won't stick or tear.

• Hand tighten the filter about 1/2 to 3/4 of a turn after the gasket makes contact. Over-tightening may damage the threads or gasket, and make the filter difficult to remove the next time the oil is changed. Under-tightening may allow the filter to work loose and leak.

• If the oil is badly contaminated or sludged, the crankcase should be cleaned and flushed before the engine is refilled with oil.

• Always check the oil level after refilling the crankcase. Start the engine, then shut it off and check the oil level after several minutes. It should be at the full mark on the dipstick. Most engine hold about four quarts of oil, plus half a pint to almost a quart for the filter (depending on the size of the filter). Overfilling can cause oil foaming and leaks. Under-filling may cause a loss of oil pressure and engine damage!

• Dispose of your old used oil properly. Save it in a container and take it to an auto parts store or other facility that recycles oil. Do NOT dump it on the ground, down a storm sewer or anyplace else where it can contaminate ground water.

Why oil needs to be changed

Regardless of an oil's API service rating or additive package, all motor oils eventually wear out and have to be changed (actually, it's the additives that wear out more so than the oil). As the miles add up, motor oil loses viscosity and gets dirty. The oil no longer has the same viscosity range it had when it was new, and it contains a lot of gunk (moisture and acids from combustion blowby, soot, dirt and particles of metal from normal wear). You can't really tell much about the condition of the oil by its appearance alone because most oil turns dark brown or black after a few hundred miles of use.

The oil filter will trap most of the solid contaminants, and the Positive Crankcase Ventilation (PCV) system will siphon off most of the moisture and blowby vapors -- if the engine gets hot enough and runs long enough to boil the contaminants out of the oil. Even so, after several thousand miles of driving many of the essential additives in the oil that control viscosity, oxidation, wear and corrosion are badly depleted. At this point, the oil begins to break down and provides much less lubrication and protection than when it was new. If the oil is not changed, the oil may start to gel or form engine-damaging varnish and sludge deposits -- and eventually cause the engine to fail!

Oil life depends on many factors including driving conditions (speed, load, idle time, etc.), environmental factors (temperature, humidity, airborne dirt), and engine wear. As a general rule, most experts still recommend changing the oil and filter every 3,000 miles or six months, which ever comes first. Why? Because this provides the best all-round protection for the average driver.

EXTENDED OIL CHANGE INTERVALS

In recent years, many vehicle manufacturers have extended their recommended oil change intervals to reduce maintenance costs for the vehicle owner -- and have run into trouble. The Center for Auto Safety (www.autosafety.org) has logged over a thousand complaints about oil sludging problems from motorists who thought they were following the service intervals recommended in their owners manuals but ended up with a crankcase full of sludge.

Extended oil change intervals of 7,500 or 10,000 miles or more are based on ideal operating conditions, not the type of short trip, stop and go driving that is typical for many motorists. Consequently, most drivers should follow a "severe" service maintenance schedule rather than a "normal" service schedule to protect their engines.

Severe service includes:
* Most trips are less than 4 miles.
* Most trips are less than 10 miles when outside temperatures remain below freezing.
* Prolonged high speed driving during hot weather.
* Idling for extended periods and continued low speed operation (as when driving in stop-and-go traffic).
* Towing a trailer.
* Driving in dusty or heavily polluted areas.

Some engines, such as diesels, suffer more blowby than others and typically require more frequent oil and filter changes. For most passenger car and light truck diesels, the oil should be changed every 3,000 miles without exception -- especially in turbo diesels.

Turbocharged gasoline engines also require more frequent oil changes because of the high temperatures inside the turbo that can oxidize oil. A 3,000 mile oil change interval is also recommended for all turbocharged gasoline engines.

OIL REMINDER LIGHTS

General Motors, BMW and some of the other luxury brands have done away with recommended oil change intervals altogether and now use an "oil reminder" light to signal the driver when an oil change is needed. Some technicians now refer to this as the "Replace Engine Soon" light because of the sludging problems that have resulted from extending oil change intervals too far. The oil reminder systems estimate oil life based on engine running time, miles driven, ambient temperature, coolant temperature and other operating conditions.

On some of these vehicles, the light may not come on until 10,000 miles or higher! But keep in mind that most of these engines are factory-filled with higher quality "synthetic" oil -- so be sure to replace same with same when the oil on these engines is changed.

OIL SENSORS & OIL ANALYSIS

One of the arguments against changing oil at specific mileage or time intervals is that the oil may still be good. As long as the additive levels in the oil are adequate and the oil is not oxidizing, breaking down or contaminated with fuel or coolant, there's no need to change it. Oil reminder lights are better than mileage/time intervals in this respect, but the light is still     a guesstimate that may or may not be accurate. The only way to know for sure when the oil really needs to be changed is to test it. A sample of oil can be sent to a lab for analysis, and the report can be used to establish a change interval that reduces unnecessary maintenance. Many fleets use oil analysis to dermine oil change intervals, but for the average motorist, oil analysis is too expensive and inconvenient. The cost of the oil analysis is almost as much as an oil change.

The best approach is to use a sensor to measure the condition of the oil. A new oil monitor sensor called Intellistick is now available for this purpose. The sensor replaces the dipstick, and uses a bluetooth transponder to broadcast the condition of the oil to a laptop computer PDA or even a bluetooth enabled call phone.

SYNTHETICS

Synthetic oils are oils that are refined to a much higher degree than ordinary oils. Synthetic oils are premium oils that generally have greater viscosity stability, lower pour points and can withstand higher operating temperatures. Synthetic oils improve cold starting, reduce friction, reduce oil consumption and improve fuel economy and performance -- but they typically cost about three times as much as regular motor oil.

Some suppliers of synthetic motor oils say the higher cost of the premium quality oil can be offset by extending oil change intervals. But this would depend on the operating conditions, age and condition of the engine.

Synthetic oils are a good upgrade for most engines, but are not recommended for breaking-in newly rebuilt engines.

BLENDS & SPECIALTY OILS

For motorists who want the benefits of a synthetic oil in a less expensive product, there are "synthetic blends" that mix 20 to 25% synthetic oil with conventional oil. Blends cost about a dollar a quart more than ordinary oil, and provide many (but not all) of the benefits of a full synthetic.

There are also oils that have special additive packages for specific applications such as large, heavy Sport Utility Vehicles (SUVs), turbocharged engines (extra anti-oxidants) and high mileage engines (extra viscosity improvers and anti-wear additives).

How to choose tires and wheels...

We know you've heard it before, but it's critical enough to bear repeating. It's also a bit daunting, too, that the tires on a vehicle are the one single link to the road surface. Think about that for a moment. You can have the most powerful engine, the most sophisticated transmission, the most elaborate super-trick suspension, and every other automotive widget known to mankind, but it all ain't worth a tinker's damn if the tires (and wheels) are subpar. In a way, it's really a bit strange but that's just how the operation of the automobile is.

Luckily, after examining the facts in the above-noted fashion, you can rest assured that tire technology is at an all-time high and it keeps getting better. In fact, it's actually quite amazing that while crummy tires can hurt a great car, great tires can do wonders for a less-than-fantastic car. In other words, there are some instances where tire technology is way beyond many of the cars on the road.

The technology that makes wheels and tires as good as they are is also what can make the subject quite intimidating. Our purpose here is to try and put a finer point on some of the basics of wheels and tires, and how to select them, too. Think of it as a wheel-and-tire primer that will provide you with some ground-floor facts when it comes time to make a replacement tire purchase or a wheel-and-tire upgrade.

For starters, there's tons of information on the sidewall of any tire and we cover that thoroughly in Sidewall Graffiti. There you'll find the full scoop on exactly what all the numbers mean.

If you've bought a vehicle new and come to the point where you need to replace the tires, there are several ways to go. Of course the easy way is get the exact size and make that came on the vehicle when it was new. Beyond that, you might consider going to a better quality tire or one that improves dry and/or wet handling that's still the same size as the OE tire. The next step would be to switch to a different wheel and the reasons for doing that are numerous. Some people merely want a different look for the wheel while using the same tires that came on the original wheels. While this might be OK if you want to make an appearance change right away, we think it's better to wait until you need new tires anyway, then upgrade to a larger diameter wheel and tire all at once.

Known as the plus sizing concept, this basically means that if you have a 15-inch wheel, plus one would be a 16-inch wheel and plus two would be a 17-inch wheel. But before we get further into wheels, we want to shed some light on what you should know when walking into a tire store to buy tires for your existing wheels. And, of course, this info also applies when you're doing a wheel upgrade, as well.

Choosing the tire that's right for you involves numerous considerations. But to make the process less scary, keep these two simple guidelines in mind when considering tires. First, know your expected needs and driving uses. This consideration is important to overall driving enjoyment and a well-run tire shop will help you determine your tire needs before you lay down any green. But be sure that you and the salesperson communicate accurately as to your true requirements. Second, find a source or store that you trust enough to recommend the type of tire that fits your needs. Remember, the salespeople don't know your needs, you have to tell them. If they're good, they'll ask you the right questions to come up with the right tire. For example, they'll know to factor in tread life, ride and handling, and driving conditions to help you determine which of these parameters are most important to you.

You might be wondering what some of the questions could be. Here's a list of what you should think about before entering a tire store.

Tread life considerations: What's your idea of how long a set of tires should last? Keep in mind that in some instances, a tire's wear rating is done through manufacturer testing and may not be the most accurate representation of a tire's true life expectancy. One way to get a handle on a tire's projected life expectancy (besides what they're warranted for, say, 40,000 miles for example) is to look at part of the UTQG (Uniform Tire Quality Grading) rating. The U.S. Department of Transportation requires each manufacturer to grade its tires under the UTQG labeling system and establish ratings for tread wear, traction and temperature resistance. These tests are conducted independently by each manufacturer following government guidelines to assign values that represent a comparison between the tested tire and a control tire. While traction and temperature resistance ratings are specific performance levels, the tread wear ratings are assigned by the manufacturers following field testing and are most accurate when comparing tires of the same brand. Tread wear receives a comparative rating based on wear rate of the tire in field testing following a government specified course. For example, a tire grade of 150 wears 50 percent longer than a tire graded 100. Actual performance of the tire can vary significantly depending on conditions, but the tire's UTQG tread life number can help you get in the ballpark as to how long a tire will really last.

Wet weather requirements: Most of us live in a climate where inclement weather is a factor at least part of the time. Clearly if you live in, say, Washington or Oregon, you'll want to look more closely at a capable wet-weather tire than if you're in Arizona or Nevada. For those of you in Snow Belt states, some kind of four-season type of tire will be the minimum you should consider if not an all-out snow tire for the winter that you swap for standard tires in the milder months.

Speed rating: Even in the plains and Western states like South Dakota, Nebraska, Idaho, Montana, New Mexico, Colorado, Wyoming, Utah, and Nevada where the rural interstate speed limit is 75 mph, how often do you think you're going to need a tire that's speed rated for anything over 150 mph? Be honest and knock down your required speed rating to, say, and H-speed rated tire that's still good for 130 mph. You'll pay less and likely not notice the difference in the real world. For reference, the most common speed ratings you'll come across on the majority of tires are shown in the chart below. Speed ratings signify the safe top speed of a tire under ideal conditions. For just about any street car, a V-rated tire will be more than adequate, unless the car will actually go faster than 150 mph. Usually, most ultra-high performance handling tires have a speed rating of at least V, so while you might want the ultimate handling of that type of tire, be aware that part of what you're paying for (the speed rating) is something you'll never use. For those who want tires that make a car really stick in the twisties, it ends up that many get the speed rating anyway, even though they don't need it. That's not a bad thing, but also be aware that tires with higher speed ratings are usually made from a softer rubber compound and generally will have shorter UTQG tread life ratings and, furthermore, will not actually last as long in the real world.

Q= 99 mph 

S= 112 mph 

T= 118 mph 

U= 124 mph 

H= 130 mph 

V= up to 149 mph 

Z= 149 mph and above 

W= 168 mph 

Y= 186 mph

Ride Quality: A low-profile tire such as a 50 or a 40-series looks great, but can be harsh over bumps or potholes when compared to a 55 or 60. In general, a lower profile tire also exposes the wheel to damage more easily. Lower profile tires also have stiffer sidewalls, which improves handling but increases rides harshness. It's all about compromise and there's no such thing as a free lunch.

Noise: Some tread designs are noisier than others and it varies significantly between tire brands and tread designs. If most of your driving is on lower-speed city streets, then this won't be much of a factor. But for highway driving, you'll want to consider your options, especially if you're driving an SUV on pavement most of the time. A good salesperson will be able to tell you which tires are quieter among those you're considering; even those of the same make that are in a different line can vary in road noise.

That's the basics on tires, now we'll move on to wheels. Tires wear out, but wheels don't, so why would you want to change wheels? For many there's no reason to, especially when you look at some of the very attractive wheels that come on many of today's cars as original equipment. The way we see it, why would you bother to change wheels on such cars as a Corvette C6, late-model Mustang GT or Shelby GT500, or the 17-inch or 18-inch sport package wheels that come on the current 3 series BMW?

But, of course, some cars have hokey wheels that need to be turned into flowerpots. As such, one of the two main reasons most people consider a wheel change is simply for looks. A better-looking wheel makes a world of difference on many cars and trucks.

Besides appearance, the plus concept is a key reason to switch wheels. Plus sizing your wheels and tires is the best way to improve both the performance and appearance of your vehicle. By using a larger diameter wheel with a lower profile tire it's possible to properly maintain the overall diameter of the tire, keeping odometer and speedometer changes negligible. By using a tire with a shorter sidewall, you gain quickness in steering response and better lateral stability. The visual appeal is obvious; most wheels look better than the sidewall of the tire, so the more wheel and less sidewall there is, the better it looks. The idea of plus sizing is illustrated in the photos that accompany this story. Pretend that the four wheels we show you are for the same car, rather than the Focus, Miata, and two 3 Series BMWs they're actually mounted on. Two of the wheels (the Miata and Focus) are 15 inches in diameter, while the BMW 323iT (a wagon) and 328i have 16- and 17-inch wheels. If a car has a 15-inch wheel, then upgrading to a 16-inch wheel would be plus one and a 17-inch wheel would be plus two. You could also say that if a car has a 17-inch wheel (such as many performance cars do) then going to an 18-inch wheel and tire would be a plus one. If the car has 15-inch wheels, the 18s would be a plus three.

Besides plus sizing, other factors should be considered before shelling out big bucks for wheels. The benefits of a good-quality alloy wheel are numerous. And, of course, many cars come with them as factory original equipment. Either way, you end up with reduced unsprung weight compared to steel wheels. This is a factor affecting a vehicle's road holding ability. Unsprung weight is the portion of a vehicle that's not supported by the suspension (i.e. wheels, tires and brakes) and therefore is most susceptible to road shock and cornering forces. By reducing unsprung weight, alloy wheels provide more precise steering input and improved cornering characteristics. The added strength of a quality alloy wheel can also reduce tire deflection in cornering. This is particularly critical in a car equipped with high performance tires where lateral forces may approach 1.0g. Better brake cooling is another benefit. The metals in alloy wheels are excellent conductors of heat and improve heat dissipation from the brakes. The risk of brake fade is also reduced under more demanding conditions such as spirited driving on a twisty mountain road. Additionally, alloy wheels can be designed to allow cool air to flow over the brake calipers and rotors. The lighter rotational weight of alloy wheels can even provide a slight increase in acceleration and fuel economy.

These days it's tough to buy truly bad wheels and tires. While some wheels are lower quality than others, as is also the case with tires, there are so many good ones out there that you will usually have several possibilities from which to choose. As we've said here, be straightforward with what you really need and factor it in with that ever-present budget consideration and you'll be well grounded when it comes to keeping your car or truck on the ground.

By Miles Cook (http://www.edmunds.com)

Future tire technology

When we drive our car, we forget that the entire weight of the vehicle rests on 4 small patches of rubber, and depending on how and where you are driving, those tiny contact points can change quite a bit. A partnership between Magneti Marelli, Brembo and Pirelli has recently formed to conquer these changes and provide the driver with real time information about how the tires are behaving on the road.

The project, named Cyber Tire, will use sensors molded into the tread of the tire and a series of transponders and

receives mounted on the vehicle. While you are driving, real time data about the topology of the road, tire pressure and air temperature will be recoded and sent to a computer to be compiled with other data.

What is Piston?

 PisoFrom wikipedia

A piston is a component of reciprocating engines, pumps and gas compressors. It is located in a cylinder and is made gas-tight by piston rings. In an engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via a piston rod and/or connecting rod. In a pump, the function is reversed and force is transferred from the crankshaft to the piston for the purpose of compressing or ejecting the fluid in the cylinder. In some engines, the piston also acts as a valve by covering and uncovering ports in the cylinder wall.

Components of a typical, four stroke cycle, DOHC piston engine. (E) Exhaust camshaft, (I) Intake camshaft, (S) Spark plug, (V) Valves, (P) Piston, (R) Connecting rod, (C) Crankshaft, (W) Water jacket for coolant flow.

How To Read A Tire Sidewall

P-Metric (example 1) P215/65R15 95S

P = Passenger Car

215 = Section width measured in millimeters (25.4 millimetes per inch)

65 = Aspect Ratio, which means the sidewall height is 65 percent of the section width.

R = Radial Carcass Construction

15 = Rim Diameter

95 = Load Index

S = Speed Rating - View Speed Rating Chart Below

A. Passenger car tire.

B. Width of tire diameter.

C. Ratio of height to width.

D. Radial.

E. Diameter of wheel in inches.

F. Load index & speed symbol

G. U.S. DOT safety standard code.

H. Max. cold inflation & load limit.

I. Treadwear, traction and temperature grades.

J. Tire ply composition and materials used.

The image below breaks down all the different components that make up the basic tire from the outer tread into the inner bead wires.

Engine Lubrication System

Motor oil does more than just lubricate an engine. It also forms a film on bearing surfaces that lifts and separates moving parts so they don't touch to reduce friction and wear. The oil film also acts like a shock absorber to cushion reciprocating and rotating parts. Oil also serves as a coolant for critical engine parts such as the crankshaft bearings and valve-train. Oil also helps prevent rust and corrosion inside the engine, and helps keep surfaces clean by dissolving and carrying away dirt and varnish deposits.

UNDERSTANDING VISCOSITY

"Viscosity" refers to how easily oil pours at a specified temperature. Thinner oils have a water-like consistency and pour more easily at low temperatures than heavier, thicker oils that have a more honey-like consistency. Thin is good for easier cold weather starting and reducing friction, while thick is better for maintaining film strength and oil pressure at high temperatures and loads.

The viscosity rating of a motor oil is determined in a laboratory by a Society of Automotive Engineers (SAE) test procedure. The viscosity of the oil is measured and given a number, which some people also refer to as the "weight" (thickness) of the oil. The lower the viscosity rating or weight, the thinner the oil. The higher the viscosity rating, the thicker the oil.

Viscosity ratings for commonly used motor oils typically range from 0 up to 50. A "W" after the number stands for "Winter" grade oil, and represents the oil's viscosity at zero degrees F.

Low viscosity motor oils that pour easily at low temperatures typically have a "5W" or "10W" rating. There are also 15W and 20W grade motor oils.

Higher viscosity motor oils that are thicker and better suited for high temperature operation typically have an SAE 30, 40 or even 50 grade rating.

These numbers, by the way, are for "single" or "straight" weight oils. Such oils are no longer used in late model automotive engines but may be required for use in some vintage and antique engines. Straight SAE 30 oil is often specified for small air-cooled engines in lawnmowers, garden tractors, portable generators and gas-powered chain saws.

MULTI-VISCOSITY OILS

Most modern motor oils are formulated from various grades of oil so the oil will have the best characteristics of both thick and thin viscosity oils. Multi-viscosity oils flow well at low temperature for easier starting yet retain enough thickness and film strength at high temperature to provide adequate film strength and lubrication.

A thin oil such as a straight 10W or even a 20W oil designed for cold weather use would probably not provide adequate lubrication for hot weather, high speed driving. Likewise, a thicker high temperature oil such as SAE 30 or 40 would probably become so stiff at sub-zero temperatures the engine might not crank fast enough to start.

Multi-viscosity grade oils have a wide viscosity range which is indicated by a two-number rating. Popular multi-viscosity grades today include 5W-20, 5W-30, 10W-30, 10W-40 and 20W-50. The first number with the "W" refers to the oil's cold temperature viscosity, while the second number refers to its high temperature viscosity.

WHICH VISCOSITY TO USE?

Most vehicle manufacturers today specify 5W-30 or 10W-30 motor oil for year-round driving. Some also specify 5W-20. Always refer to the vehicle owners manual for specific oil viscosity recommendations, or markings on the oil filler cap or dipstick.

As a rule, overhead cam (OHC) engines typically require thinner oils such as 5W-30 or 5W-20 to speed lubrication of the overhead cam(s) and valve-train when the engine is first started. Pushrod engines, by comparison, can use either 5W-30, 10W-30 or 10W-40.

As mileage adds up and internal engine wear increases bearing clearances, it may be wise to switch to a slightly higher viscosity rating to prolong engine life, reduce noise and oil consumption. For example, if an engine originally factory-filled with 5W-30 now has 90,000 miles on it, switching to a 10W-30 oil may provide better lubrication and protection.

For sustained high temperature, high load operation, an even heavier oil may be used in some situations. Some racing engines use 20W-50, but this would only be recommended for an engine with increased bearing clearances. Increasing the viscosity of the oil also increases drag and friction, which can sap horsepower from the crankshaft. That's why 20W-50 racing oil would not be the best choice for everyday driving or cold weather operation for most vehicles.

The latest trend in racing is to run tighter bearing clearances and use thinner oils such as 5W-30 or 5W-20 to reduce friction and drag.

What is Timing Belt/Chain?

From Wikipedia

A timing belt, timing chain or cam belt is a part of an internal combustion engine that controls the timing of the engine's valves. Some engines, like the flat-4 engine used in the VW Beetle, use timing gears. The term "timing belt" is also used for the more general case of any flat belt with integral teeth. Such belts are used for power transmission or to interchange rotary motion and linear motion, where either high loads or maintaining a specific drive ratio are important. A common non-automotive application is in linear positioning systems. Such belts have also been used in efforts to make a cleaner, lower-maintenance bicycle transmission, but have never become popular in this application.

What is Short Block?

From Wikipedia.

Short block is an automotive term describing an engine sub-assembly.

A short block is the portion of the engine block below the head gasket but above the oil pan. A flathead engine will also include the cam and valvetrain. The overhead valve style of engine will not include the aforementioned parts on the shortblock. A shortblock is usually purchased to upgrade the water jacket, piston size or bore. Assemblies typically include the crankshaft installed and balanced along with the main bearing.

A short block is considered destroyed when it either warps or cracks.

What is Cylinder head?

From Wikipedia.

In an internal combustion engine, the cylinder head sits above the cylinders and consists of a platform containing part of the combustion chamber and the location of the valves and spark plugs. In a flathead engine, the mechanical parts of the valve train are all contained within the block, and the head is essentially a flat plate of metal bolted to the top of the cylinder bank with a head gasket in between; this simplicity leads to ease of manufacture and repair, and accounts for the flathead engine's early success in production automobiles and continued success in small engines, such as lawnmowers. This design, however, requires the incoming air to flow through a convoluted path, which limits the ability of the engine to perform at higher rpm, leading to the adoption of the overhead valve head design.

In the overhead valve head, the top half of the cylinder head contains the camshaft in an overhead cam engine, or another mechanism (such as rocker arms and pushrods) to transfer rotational mechanics from the crankshaft to linear mechanics to operate the valves (pushrod engines perform this conversion at the camshaft lower in the engine and use a rod to push a rocker arm that acts on the valve). Internally the cylinder head has passages called ports for the fuel/air mixture to travel to the inlet valves from the intake manifold, for exhaust gases to travel from the exhaust valves to the exhaust manifold, and for antifreeze to cool the head and engine.

The number of cylinder heads in an engine is a function of the engine configuration. A straight engine has only one cylinder head. A V engine usually has two cylinder heads, one at each end of the V, although Volkswagen, for instance, produces a V6 called the VR6, where the angle between the cylinder banks is so narrow that it utilizes a single head. A boxer engine has two heads.

The cylinder head is key to the performance of the internal combustion engine, as the shape of the combustion chamber, inlet passages and ports (and to a lesser extent the exhaust) determines a major portion of the volumetric efficiency and compression ratio of the engine.

Engine Problems

(Source: http://www.howstuffworks.com)

So you go out one morning and your engine will turn over but it won't start... What could be wrong? Now that you know how an engine works, you can understand the basic things that can keep an engine from running.

Three fundamental things can happen: a bad fuel mix, lack of compression or lack of spark. Beyond that, thousands of minor things can create problems, but these are the "big three." Based on the simple engine we have been discussing, here is a quick rundown on how these problems affect your engine:

Bad fuel mix - A bad fuel mix can occur in several ways:

• You are out of gas, so the engine is getting air but no fuel.
  
• The air intake might be clogged, so there is fuel but not enough air.
  
• The fuel system might be supplying too much or too little fuel to the mix, meaning that combustion does not occur properly.
  
• There might be an impurity in the fuel (like water in your gas tank) that makes the fuel not burn.
  

Lack of compression - If the charge of air and fuel cannot be compressed properly, the combustion process will not work like it should. Lack of compression might occur for these reasons:

• Your piston rings are worn (allowing air/fuel to leak past the piston during compression).
  
• The intake or exhaust valves are not sealing properly, again allowing a leak during compression.
  
• There is a hole in the cylinder.
  
• The most common "hole" in a cylinder occurs where the top of the cylinder (holding the valves and spark plug and also known as the cylinder head) attaches to the cylinder itself. Generally, the cylinder and the cylinder head bolt together with a thin gasket pressed between them to ensure a good seal. If the gasket breaks down, small holes develop between the cylinder and the cylinder head, and these holes cause leaks.
  

Lack of spark - The spark might be nonexistent or weak for a number of reasons:

• If your spark plug or the wire leading to it is worn out, the spark will be weak.
  
• If the wire is cut or missing, or if the system that sends a spark down the wire is not working properly, there will be no spark.
  
• If the spark occurs either too early or too late in the cycle (i.e. if the ignition timing is off), the fuel will not ignite at the right time, and this can cause all sorts of problems.
  
• Many other things can go wrong. For example:
  
• If the battery is dead, you cannot turn over the engine to start it.
  
• If the bearings that allow the crankshaft to turn freely are worn out, the crankshaft cannot turn so the engine cannot run.
  
• If the valves do not open and close at the right time or at all, air cannot get in and exhaust cannot get out, so the engine cannot run.
  
• If someone sticks a potato up your tailpipe, exhaust cannot exit the cylinder so the engine will not run.
  
• If you run out of oil, the piston cannot move up and down freely in the cylinder, and the engine will seize.
  
• In a properly running engine, all of these factors are within tolerance.
  

Inside an Engine

Cylinder Head 

The cylinder head is also referred to as the top end of the engine. The cylinder head contains the intake and exhaust valves as well as the spark plugs. The intake valve opens to allow the fuel-air mixture into the engine. The spark plug sparks the mixture into power. The exhaust valve lets the exhaust out of the tailpipe.

Short Block 

The engine block and rotating assembly can be referred to as a short block, or bottom end. The rotating assembly is named as such for it rotates around and around on the crankshaft. Connected to the assembly are the connecting rods and pistons. The pistons work with the cylinder head to draw fuel and air into the cylinder, harness the power of the exploding mixture then expel the exhaust.

Timing Chain 

The timing chain or belt joins the spinning crankshaft with the camshaft in the cylinder head and brings the bottom and top ends together. The camshaft spins at half the speed of the crankshaft and controls when and for how long the intake and exhaust valves open and close.

Piston Travel 

The pistons travel up and down in the cylinder bores to draw in the fuel air mixture and compress it up into the cylinder head. A spark from the spark plug lights the mixture aflame and the piston travels back down into the bore. This is how the internal combustion engine makes power.

Power to the Wheels 

Since the pistons are connected to the spinning crankshaft by connecting rods, the energy from the explosion is transferred through the transmission and down onto the ground through the wheels.

SiRF Gets in Sync with Auto Industry

SiRF Technology Holdings, Inc., of San Jose, California, today announced it has partnered with M/A-COM Technology Solutions, Inc., to help create a networked GPS module that provides location information to vehicle-based communications and entertainment systems that debuted at the 2009 Consumer Electronics Show in Las Vegas in January.

SiRF also introduced the GSC3e/LPa single-chip GPS receiver, the first SiRFstarIII architecture product specifically built to meet the quality and reliability requirements of Tier-1 automotive electronics original equipment manufacturers (OEMs).

M/A-COM Technology Solutions' choice of the SiRFDRive2 GPS and dead reckoning technology, already adopted by LG Electronics and Continental Automotive Systems (formerly Motorola ACES), key suppliers to GM's OnStar system, reflects SiRF's continuing commitment to and success in the automotive telematics market, the company said. SiRF believes this market, which includes OEM telematics, eCall, mileage-based road tolling systems, advanced driver assistance systems, and vehicle location and fleet management, among others, could see accelerating growth rates over next several years as location becomes an integral part of vehicle platforms.

"Bringing 'location awareness' to the whole automotive platform is an important aspect of our vision to enable vehicle makers to use location not only for navigation but also for safety, security and other enhanced commercial location-based applications," said Kanwar Chadha, founder and vice president of marketing for SiRF. "Our alliance with M/A-COM Technology Solutions to provide a robust location platform that integrates GPS and tightly coupled dead-reckoning technology represents a significant milestone in solidifying SiRF's position in the auto industry."

M/A-COM Technology Solutions' new GPS module integrates a highly accurate SiRF GPS receiver running the SiRFDRive2 GPS dead reckoning software, a specialized GPS antenna, and a microprocessor controller and memory, as well as a CAN bus transceiver and connector, and associated software, to create a "location server" on the vehicle network that location-enables the entire vehicle, the company said.

The SiRFDRive2 software processes individual wheel tick counts, vehicle speed, and other critical sensor data the module obtains from the vehicle's CAN bus network, and combines it with GPS satellite signal measurements to calculate highly accurate position, heading, and time information available in all environments. The module then makes this information available via the CAN bus throughout the vehicle.

"Our new networked GPS module gives new telematics systems the highly accurate location information they need to deliver a variety of location-based services, including navigation, and demonstrates to the auto industry a new approach to location-enabling not only a single system but their entire vehicle platform," said Joe Thomas, president of M/A-COM Technology Solutions. "With SiRF's support and their in-depth understanding of how to utilize the remote sensor information on the vehicle-bus with their SiRFDRive2 software for anytime, anywhere positioning, we were able to deliver a singular, integrated product that provides location, heading and time information throughout the vehicle."

Auto Receiver. SiRF has also launched the GSC3e/LPa GPS receiver, the first SiRFstarIII product that is optimized to address auto industry needs. The SiRF GSC3e/LPa GPS receiver is fully automotive qualified, according to the company, and opens the door to the more widespread use of the SiRFstarIII architecture by automotive electronics OEMs to provide location information for a variety of in-dash navigation and telematics applications in cars and trucks around the world.

The GSC3e/LPa receiver undergoes the more exacting AEC-Q100 qualification process as well as stricter manufacturing, assembly and testing procedures to meet the tighter automotive quality and reliability standards compared to those for consumer devices, the company said. The GSC3e/LPa comes in a larger, automotive- compliant 0.8-mm pitch BGA package to support the high-reliability requirements of this market by enabling the use of lower cost substrates and more mature assembly processes.

The integrated SiRF GRF3i+ GPS radio's dual-range IF band filter with default 2-MHz bandwidth improves immunity against the near-band RF interference commonly found in electrically noisy vehicle environments, easing the integration into the vehicle platform while preserving GPS signal reception and performance, the company said. The GSC3e/LPa receiver also supports SiRF's premium SiRFDRive dead reckoning and SiRFInstantFix fast-start software options.

The SiRF GSC3e/LPa and an evaluation kit are available now in sample quantities. Production volumes are expected later this month.

SiRF.....

From Wikipedia, the free encyclopedia, SiRF Technology Holdings, Inc. (NASDAQ: SIRF) is a publicly traded company that manufactures a range of patented GPS chipsets and software for consumer navigation devices and systems. The chips are based on ARM controllers integrated with low-noise radio receivers to decode GPS signals at very low signal levels (typically -160dBm).

SiRF chips also support SBAS to allow for differentially corrected positions. SiRFstar III architecture is designed to be useful in wireless and handheld location-based services (LBS) applications, for 2G, 2.5G, 3G asynchronous networks.

The SiRFstarIII family is comprised of the GRF3w RF IC, the GSP3f digital section, and the GSW3 software that is API compatible with GSW2 and SiRFLoc. The chips have been adopted by major GPS manufacturers, including Sony, Garmin, TomTom and Magellan.

A pioneer in the commercial use of GPS for consumer applications, the company was founded in 1995 and has its headquarters in San Jose, California.

On 10 February 2009, UK wireless chip company CSR announced it was buying SiRF in a share deal worth 136 million dollars.

How accurates is GPS?

Today's GPS receivers are extremely accurate, thanks to their parallel multi-channel design. Garmin's 12 parallel channel receivers are quick to lock onto satellites when first turned on and they maintain strong locks, even in dense foliage or urban settings with tall buildings. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. Garmin® GPS receivers are accurate to within 15 meters on average.

Newer Garmin GPS receivers with WAAS (Wide Area Augmentation System) capability can improve accuracy to less than three meters on average. No additional equipment or fees are required to take advantage of WAAS. Users can also get better accuracy with Differential GPS (DGPS), which corrects GPS signals to within an average of three to five meters. The U.S. Coast Guard operates the most common DGPS correction service. This system consists of a network of towers that receive GPS signals and transmit a corrected signal by beacon transmitters. In order to get the corrected signal, users must have a differential beacon receiver and beacon antenna in addition to their GPS.

What's the signal?

GPS satellites transmit two low power radio signals, designated L1 and L2. Civilian GPS uses the L1 frequency of 1575.42 MHz in the UHF band. The signals travel by line of sight, meaning they will pass through clouds, glass and plastic but will not go through most solid objects such as buildings and mountains.

A GPS signal contains three different bits of information — a pseudorandom code, ephemeris data and almanac data. The pseudorandom code is simply an I.D. code that identifies which satellite is transmitting information. You can view this number on your Garmin GPS unit's satellite page, as it identifies which satellites it's receiving.

Ephemeris data tells the GPS receiver where each GPS satellite should be at any time throughout the day. Each satellite transmits ephemeris data showing the orbital information for that satellite and for every other satellite in the system.

Almanac data, which is constantly transmitted by each satellite, contains important information about the status of the satellite (healthy or unhealthy), current date and time. This part of the signal is essential for determining a position.

The GPS satellite system

The 24 satellites that make up the GPS space segment are orbiting the earth about 12,000 miles above us. They are constantly moving, making two complete orbits in less than 24 hours. These satellites are travelling at speeds of roughly 7,000 miles an hour.

GPS satellites are powered by solar energy. They have backup batteries onboard to keep them running in the event of a solar eclipse, when there's no solar power. Small rocket boosters on each satellite keep them flying in the correct path.

Here are some other interesting facts about the GPS satellites (also called NAVSTAR, the official U.S. Department of Defense name for GPS):

• The first GPS satellite was launched in 1978.
  
• A full constellation of 24 satellites was achieved in 1994.
  
• Each satellite is built to last about 10 years. Replacements are constantly being built and launched into orbit.
  
• A GPS satellite weighs approximately 2,000 pounds and is about 17 feet across with the solar panels extended.
  
• Transmitter power is only 50 watts or less.
  

Sources of GPS signal errors

Factors that can degrade the GPS signal and thus affect accuracy include the following:

• Ionosphere and troposphere delays — The satellite signal slows as it passes through the atmosphere. The GPS system uses a built-in model that calculates an average amount of delay to partially correct for this type of error.
  
• Signal multipath — This occurs when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. This increases the travel time of the signal, thereby causing errors.
  
• Receiver clock errors — A receiver's built-in clock is not as accurate as the atomic clocks onboard the GPS satellites. Therefore, it may have very slight timing errors.
  
• Orbital errors — Also known as ephemeris errors, these are inaccuracies of the satellite's reported location.
  
• Number of satellites visible — The more satellites a GPS receiver can "see," the better the accuracy. Buildings, terrain, electronic interference, or sometimes even dense foliage can block signal reception, causing position errors or possibly no position reading at all. GPS units typically will not work indoors, underwater or underground.
  
• Satellite geometry/shading — This refers to the relative position of the satellites at any given time. Ideal satellite geometry exists when the satellites are located at wide angles relative to each other. Poor geometry results when the satellites are located in a line or in a tight grouping.
  
• Intentional degradation of the satellite signal — Selective Availability (SA) is an intentional degradation of the signal once imposed by the U.S. Department of Defense. SA was intended to prevent military adversaries from using the highly accurate GPS signals. The government turned off SA in May 2000, which significantly improved the accuracy of civilian GPS receivers.
  

How GPS works?

GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use triangulation to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map. 

A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and track movement. With four or more satellites in view, the receiver can determine the  3D (latitude, longitude and altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more. 

About GPS, What is GPS?

At Wikipedia, The Global Positioning System (GPS) is a Global Navigation Satellite System (GNSS) developed by the United States Department of Defense. It is the only fully functional GNSS in the world. It uses a constellation of between 24 and 32 Medium Earth Orbit satellites that transmit precise microwave signals, which allow GPS receivers to determine their current location, the time, and their velocity. Its official name is NAVSTAR GPS. Although NAVSTAR is not an acronym, a few backronyms have been created for it. The GPS satellite constellation is managed by the United States Air Force 50th Space Wing. GPS is often used by civilians as a navigation system.

After Korean Air Lines Flight 007 was shot down in 1983 after straying into the USSR's prohibited airspace, President Ronald Reagan issued a directive making GPS freely available for civilian use as a common good. Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, and hobbies such as geocaching. Also, the precise time reference is used in many applications including the scientific study of earthquakes. GPS is also a required key synchronization resource of cellular networks, such as the Qualcomm CDMA air interface used by many wireless carriers in a multitude of countries.

The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the Timation satellite which proved the ability to place accurate clocks in space, a technology that GPS relies upon. In the 1970s, the ground-based Omega Navigation System, based on signal phase comparison, became the first worldwide radio navigation system.

The design of GPS is based partly on similar ground-based radio navigation systems, such as LORAN and the Decca Navigator developed in the early 1940s, and used during World War II. Additional inspiration for the GPS came when the Soviet Union launched the first Sputnik in 1957. A team of U.S. scientists led by Dr. Richard B. Kershner were monitoring Sputnik's radio transmissions. They discovered that, because of the Doppler effect, the frequency of the signal being transmitted by Sputnik was higher as the satellite approached, and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion. GPS works in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS.