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فولكس فولكس فاجن Volkswagen من اكثر السيارات مبيعاً فى العالم وتضم حاليا شركات سكودا وابيزا واودى وتستحوز عليها بورش الالمانية من اشهر سياراتها بيتلز جولف بولو جيتا باسات توران وطوارق وسوران كروس فوكس |
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SAAB should be here nearly soon due to the same soLe agent for V.W in egypt is a deaLer for Spyker Cars TOO !!
take a good Look for this very smart engine
saab svc engine concept promo 2000 Prodrive Variable Compression Ratio Engine
For example, 95 octane gasoline has the same resistance to self-ignition as a mix of 95% octane and 5% heptane. But why do we need fuel with high resistance to self-ignition under pressure? The answer is simple, the efficiency of the engine depends of the compression ratio, thus how much the air-fuel mix will be compressed before the ignition. If in a given engine we use gasoline with lower octane rating than necessary we will cause a lot of damage. Not only the fuel-air mix will ignite early but also that ignition is sudden and uncontrollable. There will be multiple flame fronts and sudden pressure spikes instead of a controlled ignition that we normally have with spark plug. The main parameters that dictates what kind of fuel is suitable for every engine are three, the geometric compression ratio, the electronic fuel and ignition management and the existence or not of a supercharger. 1).The geometric compression ratio is defined from the ratio of the cylinder volume with the piston at the TDC to the cylinder volume with the piston at the BDC. The geometric compression ratio is fixed for a given engine and can only be change with mechanical alterations (ex piston change). 2).The electronic fuel and ignition management is a more complicated matter. In a piston engine theoretically the ignition should take place when the piston crown reaches the TDC. If the fuel-air mix ignites earlier the exhaust gases will provide a resistance at the -still going upwards- piston, if it ignites after the TDC pressure potential is wasted during the distance that the piston has already travel downwards. (engine with separate ignition coil per cylinder and advanced electronic ignition management - photo SAAB) The world, 'theoritically' we used in the previous paragraph is very important. It implies that combustion occurs instantly in zero time, which may be almost the case in very low revving engines but the usual car and motorcycle engines behave differently. The optimum timing for ignition is to take place without decelerate the ascend of the piston to TDC and without waste downward piston travel (after the TDC) and energy. The fuel-air mix needs a certain time to fully combust and the available time the piston stays around the TDC decreases the more the engine spins in higher revs. The optimum ignition time is the one that will give the maximum gas pressure when the piston is in the TDC, thus in high revs the ignition must start when the piston is still ascending to give time for the pressure to build up until it reach the TDC. The adjusting mechanism of the optimum ignition timing is called 'Timing advance' and in modern cars and bikes is electronically controlled from the electronic ignition. If the electronic ignition is advanced and there also is a knock sensor an engine even if it is set up to use 98-octane fuel can also operate safely with slightly lower octane rating gasoline. In that case the ignition takes place earlier during the ascend of the piston. That may reduce the efficiency and the power of the engine but it also prevents fuel mix self-ignition and engine wear. Contemporary engines can tolerate lower octane fuel or take advantage of high-octane fuel to a point. In reality even a very advanced electronic ignition can do much by itself. A normally aspirated car with indirect fuel injection has almost insignificant power benefit from higher-octane fuel that borders in the statistic error when measured in a dynamometer. A high-revving motorcycle engine with a high compression ratio may have some benefit but small nonetheless. One can tune an engine to exploit high-octane gasoline and thus be more efficient and powerful but then the use of regular 95-octane unleaded may damage it. Direct injection with pilot fuel injection, multi-phase injection and stratified charge have more ways to exploit a better fuel and even if they are tuned for high-octane fuel use are very flexible with normal gasoline. Dynamometer tests show a detectable and sometimes significant benefit from high-octane fuel use in those engines.
variable compression apparently saab already showed the engine to the public in 2000, but this is the first time i read anything about it. if they ever manage to get this into production, it sure will give some very cool engines. the prototype is a 1.6l, with variable compression, rangeing from 8:1 to 14:1, with an output of 225bhp |
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رد: SAAB should be here nearly soon due to the same soLe agent for V.W in egypt is a deaLer for Spyker Cars TOO !!
موضوع في غير مكانه ......... عكل الله يعطيك العافيه
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رد: SAAB should be here nearly soon due to the same soLe agent for V.W in egypt is a deaLer for Spyker Cars TOO !!
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#4
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رد: SAAB should be here nearly soon due to the same soLe agent for V.W in egypt is a deaLer for Spyker Cars TOO !!
المعرفة قوة شكرا CAR ADMIRE عل كم المعرفة التى تقدمها
شركة ساب شركة سويدية تصنع السيارات السيدان الرائعة الى الصواريخ الى الطائرات الخاصة والطائرات المقاتلة اعتقد ان هذه السيارات مرتفعة الثمن لانى لا اسمع ان لها توكيل فى مصر برغم ان الصين اخذت لها نصيب لتصنع هذه السيارات وتطرحها للسوق الصينى السيارات لى سؤال لسيادتك من يركب هذه السيارات هل هى منتشرة فى اى بلد ماهى البلاد التى تباع فيها السيارات الساب بكثرة وانتشار وشكرا جزيلا
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God grant me the serenity to accept the things I cannot change courage to change the things I can and wisdom to know the difference DR Elmanahry
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#5
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رد: SAAB should be here nearly soon due to the same soLe agent for V.W in egypt is a deaLer for Spyker Cars TOO !!
IT IS VERY COMMON IN THOSE COUNTRies USA UK GERMANY UAE abu dhabi CANADA NEW ZEALAND ,AUSTRALIA, austria, netherland AND OF SURE the mother country swedish |
الكلمات الدليلية |
ساب, saab, كارز ادماير |
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