Answers - Quiz 4 Every quiz post is a learning for me. This time its much richer! Thanks BHPians. As I have always maintained, this is an very knowledgeble group. 1.Short journeys affect fuel economy more in petrol cars why? When a petrol engine is started from cold it needs loads of fuel to make it run properly. If you do short journeys all the time then you'll never get anywhere near the manufacturers stated fuel economy. Diesel cars are great for short journeys because their efficiency is almost as high cold as hot. I go with Ajmat. 2. Why does a diesel car last longer? ...because petrol destroys lubrication and diesel doesn't. Cold start-ups are a real killer for petrol engines 'cos of all that excess petrol floating about. I go with Ajmat. tsk1979 you have valid points too to support the contarary. 3. Indica Xeta Petrol 1396 cc produces Maximum Torque of 122 Nm @ 2600 rpm where as Indica V2 Diesel 1405 cc produces a Maximum Torque of only 85 Nm @ 2500 rpm, about 30% less and indica V2 turbo gives 123 Nm @ 2500 rpm. Why the difference? Agree with tsk1979 when he says "....it all depends on engine, and engine management systems. There are 1.2L engines producing 90bhp too, and 2L engines producing just 60bhp etc.,.." What I meant was ceteris paribus, if what make a diesel engine deliver less torque than petrol. The amount of power which an engine can produce is limited by how much fuel it can burn, and the amount of fuel it can burn is limited by the amount of oxygen in the cylinder. The amount of oxygen in the cylinder is limited by the amount of air in the cylinder. So, if more power is wanted then more air is needed, how do we achieve this? Well a large engine has more air, so can produce more power, or the air can be pressurized to pack more of the stuff in to the available space. This is what a turbocharger ( or a supercharger) does; it's simply an air compressor. 4. Diesel cars are immune to cold mornings which frequently affects petrol cars. Why? There you go Ajmat. No spark plug, for Diesel because the air is so hot, and so compressed at the top of the compression stroke that when the fuel is injected it burns straight away. Hence diesels can be correctly termed as "compression ignition" engines. A petrol engine is a "spark ignition" engine. This means no breakers, coil or h.t. leads to go wrong. This makes diesels immune to cold and damp that can affect petrol engines. Practically what iraghava says might be right. tsk1979, you are right - for very cold conditions this is not true.
5. Fiat group pioneered this technology which made diesel engines smooth, less noisy and immensely fuel efficient. What Technology? Fiat group did it first in passenger cars only. I stand corrected tsk1979. "The common rail system prototype was developed in the late 1960s by Robert Huber of Switzerland. After that, Ganser of the Swiss Federal Institute of Technology developed the common rail technology further. In the mid-nineties, Dr. Shohei Itoh and Masahiko Miyaki, of the Denso Corporation, a Japanese automotive parts manufacturer, developed the Common Rail Fuel System for Heavy Duty Vehicles and finally turned into its first practical use on their ECD-U2 Common Rail system, which was mounted on the Hino Raising Ranger truck and sold for general use in 1995. The modern common rail system was extensively prototyped in the 1990's, with collaboration between Magneti Marelli, Centro Ricerche Fiat and Elasis. After research and development by the Fiat Group, the design was acquired by the German company Robert Bosch GmbH for completion of development and making suitable for mass-production. In 1997 they extended its use for passenger cars. The first passenger car that used the common rail system was the 1997 model Alfa Romeo 156. Have a peppy weekend! |