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Mar 13, 2012 automotive engineering Leave a comment
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The overhead valve or OHV engine is popularly known as I-head engine or pushrod engine. It is a kind of piston engine which places camshaft in cylinder block (generally beside and little over the crankshaft in the straight engine or over the crankshaft directly in V of the V engine). It uses the rods or pushrods to actuate the rocker arms on top of the cylinder head for actuating the valves.
The toppers or lifters are placed within engine block in between of pushrods and camshaft.
The recent overhead camshaft or OHC designing (literally still the overhead valve) tends to not use pushrods and puts the camshaft within cylinder head. You have to understand this point very carefully to get the best idea of it.
During 1949, Oldsmobile gave the Rocket V8. This was the first I-head design featuring high-compression. It behaves as the archetype for most of the pushrod engines coming in the modern time. It is interesting to note that General Motors has established itself as the largest producer of pushrod engines in the world. It is known to produce both V8 and V6 pushrod engines and simply excels in this
field.
The few pushrod kind engines stay in production at the exterior of the US market. Even the American manufacturer Ford is no longer offering the pushrod engines for new vehicles. It is partly due to some countries getting laws towards taxing the engines that depend on displacement, as displacement gets to some extent related to the fuel efficiency and emissions of the vehicle. Due to this the
OHC engines have some regulatory benefit in such countries. As a result, some manufacturers are keen to design the OHV as well as OHC engines.
During 2002, Chrysler started a new kind of pushrod engine called the 5.7 liter Hemi engine. This Chrysler Hemi engine displays the advanced features like variable displacement technology. It has developed as a perfect option for numerous buyers.
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Sep 14, 2011 Finance 2 Comments
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thomossanjeet
You must have gone through the attractive car advertisements in which they offer a zero percent APR (Annual Percentage Rate) on the loan for the car. You don’t believe on the ads as you know there are very fine conditions that often make anything irrelevant.
You have money and you feel better off without the auto loan. But interestingly such loan offers in fact benefit only those better off!
The foremost condition with these loans is that the buyer of the car should have a good credit history. More specifically a credit score of over 700 points is sought.
Now those over 90 percent of the buyers fall below this credit score. So is it not wise to look for your credit score and take benefit of these loans if you qualify?
It is but all the easier to obtain your credit score thanks to the online services of the agencies engaged in the business of tracking all the financial transactions of people.
Whenever you buy anything using your credit card and pay the bills timely, the credit card company sends report of your transactions to the credit agencies that update it in your report. They also assign you a score and keep updating that at a regular interval.
You can easily know your credit score by visiting to the websites of these agencies. You can also get the detailed credit report and even can register a complaint with them if you find any inconsistency in the report.
The good thing is that they perform their services in real time. So when you come to know of your exact credit score, you may find you are well above the qualification mark.
If you are a little below it, you only need to make a good payment (like by buying something)and you may find you are above the mark (of 700 points, say) soon.
The money that you don’t pay instantly but in installments over the next three years, can well be invested in some other project!
Jul 21, 2011 Automotive Leave a comment
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A new Ferrari 458 racer joined the fray. The North American Grand Am looking vicious. The new Ferrari developed with racer specialists Michelotto Automobili.
Ferrari 458 Italia Grand Am’s remarkably similar to the Euro-spec 458 Italia GT3. It get less aero kit but no traction or ABS control and a detuned 500bhp V8 to meet with series regs.
Jun 4, 2011 Auto Parts Comments Off
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Have you tried to figure out the crossplane crankshaft designing used in V8 engines? Do you want to know the concept involved here. You surely must be getting curious to know the details of it. If you are keen to know more read this discussion further.
The crossplane is a type of crankshaft designing used in V8 engines where there is an angle of 90° between the banks of cylinder.
There are four crankpins in it. Each of them is offset at an angle of 90° from adjacent crankpins. The first and fourth crank pins are placed at angle of 180° to one another. This is also true for second and third. Each of these pair is at an angle of 90° to one another. If you view this from end it takes the shape of a cross.
It is interesting to note that crankpins are placed in 2 planes and are crossed at an angle of 90°. Due to this it gets the name of crossplane. The crossplane crank can have 5 main bearings. It generally does well like larger balancing weights.
The crossplane V8s make use of firing patterns that are uneven within each of the cylinder banks. This results in a distinguishing burble in exhaust note. Although, the overall firing pattern is even. Due to the balance of second order involved here there is no requirement of added balance shaft for achieving remarkable smoothness.
For the first time crossplane was introduced by Cadillac in 1923. Peerless followed this with a one in 1924.
Apr 28, 2011 Cars 1 Comment
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All good versions of car become even better with positive modifications. These changes are very necessary for getting best results. The same thing happened with the Porsche 997.
It got revision in 2008 for 2009 model year. You should note that the updated Porsche 911 is known as 997 Gen II. It contained several changes like – the revised suspension, revised front bumper having large air intakes, headlamps, latest direct injection engines having redesigned PSE and redesigned PCM system having optional hard-drive touch-screen navigation. The Tiptronic S option got replaced by the PDK dual clutch 7-speed transmission. The production started in the end of 2008. This car was revealed at the Paris Auto Show in 2008.
The Turbo Cabriolet is the facelifted version of 997 Turbo. It was revealed at the Frankfurt Motor Show in 2009. This model got a entirely new 3.8 liter 6-cylinder boxer engine. It can produce a power of 500 hp or 370 kW. It has revised Borg-Warner VTG turbos.
You can now get the 911 Turbo with the manual gearbox or optional 7-speed PDK dual-clutch gearbox. It replaced the Tiptronic. Porsche claims that 911 turbo can accelerate from 0 to 100 km/h or 62 mph in just 3.4 seconds. It can attain the maximum speed of 312 km/h or 194 mph.
But, many tests performed by unpartial testers and Auto-Magazines have shown that the time to accelerate from 0 to 100 km/h is normally very low at 2.9 seconds.
Feb 15, 2011 Automotive Leave a comment
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Several old V6 engines used V8 design as their basis. Here a cylinder pair was cut off from the V8 front and V angle was not altered. Sometimes a more advanced crankshaft was used so that the firing interval could be even out. Mostly the V8 engines have common crankpin located between the opposite cylinders of each bank. The 90° V8 crankshaft contains only four pins which the eight cylinders share. There are two pistons for every crankpin. Because of this the cylinder fires every 90° for achieving smooth operation.
The earlier 90° V6 engines that were derived from V8s contained three shared crankpins. These were placed at 120° to each other, like the inline 3-cylinder. The cylinder banks got placed at 90° with each other. It caused a firing pattern with the groups where two cylinders were separate by 90° rotation and groups separate by 150° rotation. This resulted in an odd-firing of notorious behavior. The cylinders fired at alternating intervals of 90° and 150°. The uneven intervals of firing caused rough running engines having unlikable harmonic vibrations at some engine speeds.
The later 90° V6 engines prevent this problem by making use of split crankpins. Here the adjacent crankpins are offset by 15° in the opposite directions for achieving an even ignition pattern of 120°. This ‘split’ crankpin has less strength as compared to the straight one. However, it is interesting to note that the latest metallurgical techniques can manufacture a crankshaft having adequate strength.
In the year 1986, the 90° PRV engine used the 30° crankshaft offset designing so that its firing could be even out. Buick launched a V6 engine in 1988 that besides having split crankpins also had a balancing shaft counter-rotating between cylinder banks. This was necessary for eliminating almost all the primary as well as secondary vibrations. This resulted in an engine having very smooth run.
Jan 16, 2011 Automotive Leave a comment
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Propulsion systems used in boats and ships are found in different types. They could vary from simple paddle to large diesel engines to nuclear propulsion. The propulsion systems could be divided into three divisions – human propulsion, mechanical propulsion, and sailing. In present time, human propulsion is generally found in small boats. Besides this, you can also find it on sailboats in the form of auxiliary propulsion.
Propulsion method adopted by sail usually requires an erect mast on which sail is hoisted. Spars and stays are used for supporting it and ropes are required for controlling. Sail system was very popular in the earlier time. But, now they are mainly used for racing and recreation purposes.
In mechanical propulsion usually an engine or motor is used for turning the propeller. In earlier time, this was done through steam engines. However, in present time four stroke and two stroke diesel engines, gas turbine engines and outboard motors are used on fast ships.
Jan 5, 2011 Auto Parts Comments Off
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Jaguar C-X75 made its debut at the Paris Motor Show in 2010. This two seat, plug-in hybrid, concept car has been produced by Jaguar. This car produces a power of 778 hp. There are four electric motors used in it and each one of them drives one wheel out of the four.
Two micro gas turbines that are diesel fed are used for recharging the batteries of these motors. Earlier four-stroke engines were used for this purpose. In the model name C-X75, C is used to denote concept and X is used to denote experimental.
This car has an excellent performance. It has the capability to reach the speed of 330 km/h. It can accelerate from the speed of 0 to 100 km/h in only 3.4 seconds.
Also, it can accelerate from 80 km/hr to 145 km/h in only 2.3 seconds. Four electric motors of 194 hp are used here. The total torque generated is 1,600 Nm.
Dec 25, 2010 Bikers Comments Off
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Harley-Davidson has been producing Sportster motorcycles since 1957. The code of the Sportster models by this company starts with XL. These models make use of overhead valve engine. The Sportster motorcycles use V-twin 45 degree engines.
There is a single crank pin for two connecting rods. The Sportster engine that was originally used was called Ironhead engine. Then Evolution engine came in 1986 to replace it.
Till 2003 model year engine was directly mounted on the frame. With this layout the bike happens to be lighter and follows a precise handling. The engine vibrations are transmitted to a rider directly.
Since 2004 and the following models of Sportster tie links and rubber isolation mounts were used for limiting engine movement in a single plane. Because of it the vibrations that the rider felt were drastically reduced. Buell motorcycles have utilized rubber mount systems from 1987 onwards.
Dec 12, 2010 Cars Comments Off
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Volkswagen Group unveiled Nardo W12 Coupé at the Tokyo Motor Show in 2001. It was a rear wheel drive, mid engined supercar. It made use of W12, 6.0 litre engine.
It produced a power of 447 KW or 600 hp. Few days before it, W12 Coupe had set the 24 hour endurance record of the world to its name. W12 Coupés were considered for manufacturing but the idea was later cancelled.
At present, Volkswagen Group manufactures W12 engines through two imaginary narrow-angled 15 degree VR6 engines that are placed at 72 degree angle. Because of this narrow angle each cylinder set requires only two overhead camshafts for driving each bank pair.
Therefore, in total only four are required. Volkswagen Group used W18 engines for Bugatti concept cars in 1998 and 1999. W12 design is different from them. The W12 engines from Volkswagen Group are at times called WR12 because of this distinction.
