Ratting such as the API and ACEA standards refer to the oil's quality. For grade , SAE ( Society of Automotive Engineers ) is the organization that grades engine oils according to their kinematic viscosity rating that describe the oil's function and viscosity standard.
ACEA.
( Association of European Car Manufacturers ) standards have three categories : A - for petrol engines . B - for diesel engines and E for commercial diesel engines.Levels of lubricants performance are expressed by a following number :1 for the fuel-economy,2 for standard performance and 3 for high performance and / or extended drain. Example : A1 describes fuel-economy petrol engine oil, A3 describes high-performance petrol engine oil.
API.
( American Petroleum Institute ) oil performance standard is expressed by two latters. The first letter indicates
whether the oil os for petrol (s) with `s' ( meaning Service category) or diesel (c) with `C' ( meaning Comercial category ) engines. The second letter special the level of technical performance within the relevant group : A for the minimum level for both petrol and diesel, and J (petrol) and F diesel for thr highest level. High performance engine oil must meet API SL standards which is indicative of the oils having standard levels of anti-wear additives, detergents and dispersants. `SM' is the current top grade, which recently replaced `SL' `SM' is basically an upgrade version of the `SL' oil that has been tested more vigorously.
There are two general grades of motor oils i.e single grade and multi -grade. Single grade oils are usually used when the operating temperature is relatively stable ( or for specific applications), meaning they cannot meet both winter and summer requirements. For applications where the temperature range is not very wide, such as in lawn mowers, single grade oils will suffice.
Multi -grade oils are made by adding viscosity index(VI) improver additives (oil-soluble organic polymer )to single-weight oils to improve th temperature range. VI is simply the measureof oils thickness and ability ti flow at certain temperatures when it is subject to heat. The benefits of adding VI improvers are the reduce viscosity
changes with temperature , reduce fuel consumption and allow easy cold starts. These oils are thin enough to work at cold temperature and safe enough to work at high temperatures ( 212 degrees test point ).
Multi-grade are given two numbers-the first number represents the base stock weight followed by the letter W (winter). "W" grade oils are defined by their ability to flow and lubricate at cold start up, 0W (-35 C) ,5W (-30C),10W (-20C), 15W (-15C),20W (-5C), the lower (low viscosity) this number, the more fluid (thinner) at low temperature , the easier th engine start. The second number represents the high temperature viscosity rating :30(+30C), 40 ( +40C) and 50 (+50C). The higher ( high viscosity ) this number , the less the oil will thin when hot, which means it will hold without breaking down at high temperatures.
The thicker an oil is, the higher its viscosity and vice versa. High viscosity oil would get in cold temperature if additives are not added to thinner single-weight base stock for good low temperature pour performance.
A VI improver is akin to a very long string which at low temperatures is tightly coiled into a small ball that floats in the oil with little effect on th oil's viscosity . However, at high temperature this ball expand, uncoils and encloses a larger volume of oil within its structure. This effectively prevents the oil from thinning because of the greater volume taken up by the expanded balls if VI improver molecules.
Oils with exceptionally high viscosity rating have more internal friction and tend to cause the oils to pump up and the engine become nosier. They may not pump to the proper parts of your engine especially at low temperatures, and the film may further tear at high RPM. Older engines need to use thicker oils such as SAE 50 because of the wear and tear of the engine.
Oils with exceptionally low viscosity (generally SAE 0W - 30) may lose its film strength it higher temperatures however ; the losses caused by friction internal to the lubricant are reduced; the petrol consumption is therefore enhanced by a few precent. Low viscosity oils such as SAE 20, 30, or 40 are thinner and reach engine parts faster on cold starts. However caution should be used as this type of oil is not suitable for all engines. Motor oils must also cater for thin film lubrication in areas of the engine where thick films can't form because the relative speed of moving parts os too slow for oil wedge formation and or because the loads are too high.
New cars perform better and get good fuel economy with API SH grade thinner 5W-30 or 10W-30 oil, thereby avoiding the possibility of ring sticking and other problems that can occur in oils loaded with VI improvers. For NA streets cars, thinner oil's low temperature flow characteristics help avoid significant wear at startup , which is much more important than a little more oil pressure in a hot engine . This is necessary in Overhead Cam Engines with cam bearing located above the oil supply. When you start your engine , let it idle for about 15 second to warm before moving off.
Choose the narrowest span with a heavier base if your temperature zone allows, a wider span means more polymers which is not good for your engine.For example 10W -30 has a narrower span than 10W-40, thus requires fewer polymers. 10W-40 required more polymers than 10W-30 to work at hot temperature. Don't make a choice of a lighter base if there's no need in the same name of temperature. For example 10W-40 has the same 30 point spread with 20W-50, but 20W-50 has a 20W base which is heavier than 10W, thus 20W-50 oils needs fewer polymers than 10W-40.
Forced induction engines such as turbo bearing can heat engine oil to the point of breakdown, Forced induction cars would therefore have dedicated oil coolers to mitigate this. Race oils are always high viscosity that is why it is hard to justify anything but synthetics due to their wider latitude of engine protection under heavy loads especially in our hot climate.
Sunday 6 February 2011
EXHAUST
A series of pipes are used to connect the various exhaust components such as the monifold, catalytic onverter,
resonator(s) and the mufler together. The lengh and cross-section of the pipes, as well as the type of junction used, influence the vehicle's performance characteristics and sound.The junctions of the various components are connected by means of insert connections, flanges or welds. Exhaust system for vehicles with larger displacements ( e.g V6 0r V8 engines ) are often fitted with twin pipes.
PROBLEM
Stock CAT-BACK system are often welded into one complete element for faster mounting - not good. The joint from welds affect the efficient exhaust flow. Moreover , the pipes are thinner with narrow angle bends causing restrictions hence introducing backpressure. Backpressure robs your engine of power ; instead of directing energy at the crankshaft, your engine has to work to push the exhaust gas out under pressure; the greater the pressure , the bigger the power loss. Some backpressure is inevitable , but should minimize in order to scavenge power that is available.
PIPE SIZING.
Many mistakenly believe that a bigger exhaust is a better exhaust . Exhaust gas is hot , and we'd like to keep it
hot throughout the exhaust system . This because cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large pipe will slow down the flow, which will in turn give the gas plenty of time to cool off en route - no good.. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which would nullify the headers purposes. This is because the pulses will not have the same tendency to line up as they would in a smaller pipe. Coating the entire exhaust system with an insulating material, such as header wrap or a ceramic ( thermal barrier ) coating would mitigate this somewhat. Albeit, there is know way of accurately calculating the optimal exhaust pipe diameter. This is mainly due to the complex nature of an exhaust system; like bends in the piping , temperature fluctuations , differences in muffler design etc. make selecting an optimum pipe diameter difficult.
SIZING RECOMMENDATIONS.
If vehicle is stock or if you are limiting yourself to bolt-ons', keep to the stock size or limit your pipe diameter to no more than 2" or you will lose some bottom end with no usable gain on top. Naturally aspirate vehicle in the 150-200 hp range should use pipe diameter between 2 to 2.25 ince s.Turbo's and V6's in the 200-250 hp
range can go for 2.25 - 2.5 inches. For engines making 250-350hp, a generally acceptable pipe diameter of between 3 to 3.5 inches is quite enough already .Extremists using 400 to 500 hp should limit the pipe size at 4 inches and no more or you may unexpectedly find a small dead dog sleeping in your exhaust one day.
ANCILLARIES.
The entire exhaust system should be connected to the underbody via insert connections and flanges with flexible suspension elements. Flanges and insert connections are preferred instead of welds to enhanced flow dynamics. The welds reduced the pipes diameter on the insides and affect the smooth exhaust flow.Avoid the typical crush bends and instead opt for mandrel bends which is more linear and do not alter the pipe's diameter. The fixing points must be carefully selected, otherwise vibration can be transmitted to the bodywork
and thus generate noise in the passenger compartment. Ideally use heavy duty rubber mounts with a generous standoff from the bodywork. The exhaust-system noise at the exhaust-emission point ( tailpipe ) may also cause bodywork resonances. A larger diameter designer tailpipe that adds on to the muffler tips is recommended to give the vehicle that race finish look. The design of the tail pipe and length of the muffler end will also affect the sound of the overall exhaust system. For twin exhaust system , an active lateral pipe joining both sections together after the resonator boxes is recommended to achieve some positive backpressure to help in torque - try this and be surprise.
CONCLUSION.
If you see yourself using nitrous or forced induction in future, go with the larger diameter piping now to save from double spending. If you plan on lowering your ride , make sure your new exhaust system won't cause any clearance problems ( beware of the humps ). If budget is a consideration a header will be the first upgrade option which provides the greatest bang for the buck. Next is the free flowing muffler, otherwise operate on your stock one or look for one with a bulit-in valve that allows it to be free flowing under high speeds. The valve type mufflers helps positive feedback at low speeds for acceleration like the latest generation one design for the CTR ot ITR's.
resonator(s) and the mufler together. The lengh and cross-section of the pipes, as well as the type of junction used, influence the vehicle's performance characteristics and sound.The junctions of the various components are connected by means of insert connections, flanges or welds. Exhaust system for vehicles with larger displacements ( e.g V6 0r V8 engines ) are often fitted with twin pipes.
PROBLEM
Stock CAT-BACK system are often welded into one complete element for faster mounting - not good. The joint from welds affect the efficient exhaust flow. Moreover , the pipes are thinner with narrow angle bends causing restrictions hence introducing backpressure. Backpressure robs your engine of power ; instead of directing energy at the crankshaft, your engine has to work to push the exhaust gas out under pressure; the greater the pressure , the bigger the power loss. Some backpressure is inevitable , but should minimize in order to scavenge power that is available.
PIPE SIZING.
Many mistakenly believe that a bigger exhaust is a better exhaust . Exhaust gas is hot , and we'd like to keep it
hot throughout the exhaust system . This because cold air is dense air, and dense air is heavy air. We don't want our engine to be pushing a heavy mass of exhaust gas out of the tailpipe. An extremely large pipe will slow down the flow, which will in turn give the gas plenty of time to cool off en route - no good.. Overlarge piping will also allow our exhaust pulses to achieve a higher level of entropy, which would nullify the headers purposes. This is because the pulses will not have the same tendency to line up as they would in a smaller pipe. Coating the entire exhaust system with an insulating material, such as header wrap or a ceramic ( thermal barrier ) coating would mitigate this somewhat. Albeit, there is know way of accurately calculating the optimal exhaust pipe diameter. This is mainly due to the complex nature of an exhaust system; like bends in the piping , temperature fluctuations , differences in muffler design etc. make selecting an optimum pipe diameter difficult.
SIZING RECOMMENDATIONS.
If vehicle is stock or if you are limiting yourself to bolt-ons', keep to the stock size or limit your pipe diameter to no more than 2" or you will lose some bottom end with no usable gain on top. Naturally aspirate vehicle in the 150-200 hp range should use pipe diameter between 2 to 2.25 ince s.Turbo's and V6's in the 200-250 hp
range can go for 2.25 - 2.5 inches. For engines making 250-350hp, a generally acceptable pipe diameter of between 3 to 3.5 inches is quite enough already .Extremists using 400 to 500 hp should limit the pipe size at 4 inches and no more or you may unexpectedly find a small dead dog sleeping in your exhaust one day.
ANCILLARIES.
The entire exhaust system should be connected to the underbody via insert connections and flanges with flexible suspension elements. Flanges and insert connections are preferred instead of welds to enhanced flow dynamics. The welds reduced the pipes diameter on the insides and affect the smooth exhaust flow.Avoid the typical crush bends and instead opt for mandrel bends which is more linear and do not alter the pipe's diameter. The fixing points must be carefully selected, otherwise vibration can be transmitted to the bodywork
and thus generate noise in the passenger compartment. Ideally use heavy duty rubber mounts with a generous standoff from the bodywork. The exhaust-system noise at the exhaust-emission point ( tailpipe ) may also cause bodywork resonances. A larger diameter designer tailpipe that adds on to the muffler tips is recommended to give the vehicle that race finish look. The design of the tail pipe and length of the muffler end will also affect the sound of the overall exhaust system. For twin exhaust system , an active lateral pipe joining both sections together after the resonator boxes is recommended to achieve some positive backpressure to help in torque - try this and be surprise.
CONCLUSION.
If you see yourself using nitrous or forced induction in future, go with the larger diameter piping now to save from double spending. If you plan on lowering your ride , make sure your new exhaust system won't cause any clearance problems ( beware of the humps ). If budget is a consideration a header will be the first upgrade option which provides the greatest bang for the buck. Next is the free flowing muffler, otherwise operate on your stock one or look for one with a bulit-in valve that allows it to be free flowing under high speeds. The valve type mufflers helps positive feedback at low speeds for acceleration like the latest generation one design for the CTR ot ITR's.
Wednesday 2 February 2011
Saturday 22 January 2011
Friday 21 January 2011
Capter 1
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