Have you ever imagined to see the Nations most ultimate Automotive Ingenious Minds competing against each other in a single Arena!? Ever Imagined the Momentum of their Racing!? The magnitude of their true Potential!? Their Conflict to Conquer the Ultimate Peak of Success?! Well! Why are you imagining it. See, feel & go crazy!
The Department of Automobile Engineering, Madras Institute of Technology, is all set to Rev up your brains from the Neutral with its most prestigious Techno-Management Fest “AUTOMEET 10″. Buckle up your seat belts! The race falls on March 15th. Be there!
Paper Presentation
The classic symposium special. A platform for presenting ideas that can potentially revolutionise our lives. Small or big, it doesn’t matter. What matters is the benefits that we can realise from it. So come forward to put your thoughts into action. Show us how you can change the world, one slide at a time.
Projectum
Imported C&B Show
Lose yourself in the world of Imported Metal
Auto Q
You know, tough brain-racking questions of cars & bikes you’ve never heard/seen before. And some easy ones that can still cause you to bang your head. Either way, it packs a turbo-charged punch!
Gen Q
The best place to exhibit your knowledge about Tintin’s hobbies and Genghis khan’s palace
Why?
My car hates vanilla ice cream. You know why? It doesn’t have an antipercolator, can that be a reason? Why does a spoonful of sugar in this fuel tank prevent a car from starting? If u think u can answer these questions. You know where to head up to.
RC Car Race
Lets give your brains a break. Let your fingers do the racing.
Non – IC RC Car Race
Drag Race
Air Car
Ever thought of doing something useful with your emptied coke bottle other than throwing it to the bin?! Well! We have got the place which you have been looking for! Think Innovative! Showcase your talents.
Virtual Remodelling
Don’t have the dough to buy and remodel a new car? Why not do it in a computer. After all, that pretty much what we all have been doing in NFS, right? Show us how good you are at transforming a lemon into a limousine. With the help of some virtual car ‘editing’ softwares , of course.
Cad Modelling
Precision engineering begins here. Wield the powers of CATIA and PRO-E to give shape to your thoughts. Show us that design and analysis that can be done without breaking into a sweat.
Car Sketching
Some people tend to ask: What’s so great about sketching? Even small kids draw cars from their flights of fantasy. Does that quality? Actually it does. There is no car in the world which originated without a simple sketch. Such is the importance of car sketching that Giorgetto Giugiaro, of all people, swear by it, so you know that you’re up to. Sketch a car that you think will make people fall head over heels just looking at it. Aesthetics takes the front seat here, and if stuff like aerodynamics and ergonomics have a role to play, you can get some brownie points!
Contraption
Tech Xword
Tougher than the Guardian. More challenging than the Hindu. Are we selling newspapers? No, is just our auto crossword. So big that you’ll need a couple of hours to solve it. And given just one hour to do so. What’s life without a challenge, you say?
PC Gaming
The ultimate test of your communication, determination, accuracy and presence of mind. The CS Mini-Tourney at Automeet will be a tactical warzone for the meanest clans in Chennai. Everyone is invited to show their proness. Prove that you can mag, drag and pull a headie with ease. Be there or Be square.
For Further Details: www.automeet10.com
The Bugatti Veyron EB 16.4 is the most recent version of a mid-engined full-sized grand tourer developed by the German car-manufacturer Volkswagen and produced by the Volkswagen-brand Bugatti Automobiles SAS at their headquarters in Château St. Jean in Molsheim (Alsace, France), and whose production and development is often credited to Ferdinand Karl Piech. It is named after French racing driver Pierre Veyron, who won the 24 hours of Le Mans in 1939 while racing for the original Bugatti company. It was named “Car Of The Decade” by the BBC television programme Top Gear.
Two hundred and twenty Veyrons are known to have been built and delivered since production began in 2005 and ended in late 2008. Special variants of the Veyron include the Pur Sang, the Fbg Par Hermes, the Sang Noir, the Targa, the Vincero, and the Bleu Centenaire. It will be replaced with the Grand Sport, which is essentially a Veyron convertible.
The Veyron features an 8.0 litre W16 engine — sixteen cylinders in two banks of eight cylinders, or the equivalent of two narrow angle V8 engines mated in a “W” configuration. Each cylinder has four valves for a total of sixty four, but the narrow staggered eight configuration allows two overhead camshafts to drive two banks of cylinders so only four camshafts are needed. The engine is fed by four turbochargers and displaces 7,993 cubic centimetres (487.8 cu in), with a square 86 mm by 86 mm (3.4 in × 3.4 in) bore and stroke.
The transmission is a dual clutch Direct-Shift Gearbox computer-controlled automatic with seven gear ratios, with magnesium paddles behind the steering wheel and a shift time of less than 150 milliseconds. This is designed and manufactured by Ricardo of England (and not Borg-Warner who designed the six speed DSG used in the mainstream marques of the Volkswagen Group). The Veyron can be driven in either semi automatic or fully automatic mode. A replacement transmission for the Veyron costs just over $120,000. It also features fulltime permanent four wheel drive, using the Haldex Traction system. It uses special Michelin PAX run flat tyres, designed specifically for the Veyron to accommodate its top speed, which reportedly cost $25,000 US per set. The tyres can only be removed from the rims in France, a service which reportedly costs $70,000. Kerb weight is 2,034.8 kilograms (4,486 lb). This gives the car a power to weight ratio, according to Volkswagen Group’s 736 kilowatts (1,001 PS; 987 bhp) figures, of 446.3 bhp per ton.
The car’s wheelbase is 2,710 mm (106.7 in). Overall length is 4,462 mm (175.7 in), width 1,998 mm (78.7 in) and height 1,204 mm (47.4 in).
The Bugatti Veyron has a total of ten radiators.
It has a drag coefficient of 0.41 (normal condition) and 0.36 (after lowering to the ground), and a frontal area of 2.07 square metres (22.3 sq ft). This gives it a CdA ft² value of 8.02.
According to Volkswagen Group, the DIN rated motive power output, approved by TÜV Süddeutschland, of the final production Veyron engine produces 1,001 metric horsepower (736 kW; 987 bhp) and generates 1,250 newton metres (922 ft·lbf) of torque. The figure has been confirmed by Bugatti officials to actually be conservative, with the real total being 1020 bhp or more.
The top speed was verified by James May on Top Gear for the November 2006 issue, again at Volkswagen Group’s private Ehra-Lessien test track, where the final-production car hit 407.9 km/h (253.5 mph), which equated to almost one-third of the speed of sound at sea level. As the Bugatti Veyron approached the top speed during the test, May said that “the tyres will only last for about fifteen minutes, but it’s okay because the fuel runs out in twelve minutes”. He also gave an indication of the power requirements: at a constant 155 mph, the Veyron is using approximately 270 metric horsepower (200 kW; 270 bhp); the next 100 mph requires an additional 730 metric horsepower (540 kW; 720 bhp). Jeremy Clarkson, driving a Veyron from Italy to London, noted that at top speed, the engine consumes 10,000 imperial gallons (45,000 L) of air per minute (as much as a human breathes in four days). With a 0 to 60 time of 2.4 seconds, the Veyron was the fastest legal street car between the years 2005 and 2007. Once back in the Top Gear studio, May was asked by co-presenter Jeremy Clarkson what the Veyron felt like to drive at 407 km/h (253 mph), May replied that it was “totally undramatic”, and very stable at speed.
German inspection officials recorded an average top speed of 408.47 km/h (253.81 mph)[19] during test sessions on the Ehra-Lessien test track on 19 April 2005. The Bugatti website still refers to the Veyron as the fastest production vehicle of all time even though this title has since been taken by the SSC Ultimate Aero TT.
The car’s everyday top speed is listed at 350 km/h (220 mph). When the car reaches 220 km/h (140 mph), hydraulics lower the car until it has a ground clearance of about 9 cm (3.5 in.). At the same time, the wing and spoiler deploy. This is the “handling mode”, in which the wing helps provide 3,425 newtons (770 lbf) of downforce, holding the car to the road, and helping the Bugatti Veyron perform 1.34 g forces on a 300 foot skidpad.[13] The driver must, using a special key (the “Top Speed Key”), toggle the lock to the left of his seat in order to attain the maximum (average) speed of 407 km/h (253 mph). The key functions only when the vehicle is at a stop, when a checklist then establishes whether the car and its driver are ready to enable ‘top speed’ mode. If all systems are go, the rear spoiler retracts, the front air diffusers shut and the ground clearance, normally 12.5 cm (4.9 in), drops to 6.5 cm (2.6 in).
The Veyron’s brakes use cross drilled, radially vented carbon fibre reinforced silicon carbide (C/SiC) composite discs, manufactured by SGL Carbon, which have a much greater resistance to brake fade when compared with conventional cast iron discs. The lightweight aluminium alloy monobloc brake calipers are made by AP Racing; the fronts have eight titanium pistons and the rear calipers have six pistons. Bugatti claims maximum deceleration of 1.3 G on road tyres. As an added safety feature, in the event of brake failure, an anti-lock braking system (ABS) has also been installed on the handbrake.
Prototypes have been subjected to repeated 1.0 G braking from 312 km/h (194 mph) to 80 km/h (50 mph) without fade. With the car’s acceleration from 80 km/h (50 mph) to 312 km/h (194 mph), that test can be performed every 22 seconds. At speeds above 200 km/h (120 mph), the rear wing also acts as an airbrake, snapping to a 55-degree angle in 0.4 seconds once brakes are applied, providing an additional 0.68 G (4.9 m/s²) of deceleration (equivalent to the stopping power of an ordinary hatchback). Bugatti claims the Veyron will brake from 400 km/h (250 mph) to a standstill in less than 10 seconds.
The Bugatti Veyron is a car built around an engine. Essentially, Bugatti made the decision to blow the doors off the supercar world by creating a 1,000-horsepower engine. Everything else follows from that resolution.
So let’s start with the engine. How would you begin the design process for an engine this powerful? If you have know how a car engines works, you know that if you want to create a 1,000-horsepower engine, it has to be able to burn enough gasoline to generate 1,000 horsepower. That works out to about 1.33 gallons (5 liters) of gasoline per minute.
We need a 16-liter engine to burn 1.33 gallons of gas per minute. That actually makes sense — the engine in the Dodge Viper is 8.0 liters in displacement and produces 500 hp.
But there’s a problem: A 16-liter V-8 engine would be very large. And the pistons would be massive, so there would be no way it could turn at 6,000 rotations per minute (rpm). It might turn at a maximum of 2,000 rpm, meaning that you would need an immense 48-liter engine to generate 1,000 hp. Clearly an engine that big is impossible in a passenger car.
So how did Bugatti fit 1,000 horsepower into a passenger car?
Bugatti did two things to create a compact engine capable of producing 1,000 hp.
The first and most obvious thing is turbocharging.
The Bugatti Veyron’s 16-cylinder monster engine produces 1,001 horsepower for a top speed of more than 250 mph. And it’s a passenger car. Check out the Bugatti. Amazing isn`t it? If you have know how a turbocharger works, you know that one easy way to make an engine more powerful without making the engine bigger is to stuff more air into the cylinders on each intake stroke. Turbochargers do that. A turbo pressurizes the air coming into the cylinder so the cylinder can hold more air. If you stuff twice as much air in each cylinder, you can burn twice as much gasoline. In reality, it’s not quite a perfect ratio like that, but you get the idea. The Bugatti uses a maximum turbo boost of 18 PSI to double the output power of its engine. Therefore, turbocharging allows Bugatti to cut the size of the engine from 16 liters back down to a more manageable 8 liters. To generate that much air pressure, the Bugatti requires four separate turbochargers arranged around the engine.
The second thing Bugatti engineers did, both to keep the RPM redline high and to lower lag time when you press the accelerator, was to double the number of cylinders.
The Bugatti has a very rare 16-cylinder engine.
There are two easy ways to create a 16-cylinder engine.
The latter technique is, in fact, the way Bugatti created its first 16-cylinder cars in the early 20th century.For the Veyron, Bugatti chose a much more challenging path. Essentially, Bugatti merged two V-8 engines onto one another, and then let both of them share the same crankshaft. This configuration creates the W-16 engine found in the Veyron. The two V’s create a W.
The special features of the Bugatti W-16 engine are amazing. For example:
Everything about the engine is superlative.And it is remarkably compact. It measures just 710 mm (27 inches) long, 889 mm (35 inches) wide and 730 mm (28.7 inches) high. This is the beauty of Bugatti’s W-16 approach — the engineers managed to fit 1,000 hp into a reasonably sized package.
Transmission
The transmission is unique, in particular because it has to harness about twice as much torque as any previous sports-car transmission. It has:
This computer-controlled system is identical to the sort of system found in a Formula 1 car or a Champ car. There is no clutch pedal or shift lever for the driver to operate — the computer controls the clutch disks as well as the actual shifting. The computer is able to shift gears in 0.2 seconds. It would be almost impossible for all of the torque available from the W-16 engine to flow out to just two wheels without constant wheel-spin. Therefore, the Veyron has full-time all-wheel drive. By applying the engine’s power to all four wheels through a computer-controlled traction-control system, the car is able to harness all of the engine’s horsepower, even at full acceleration.
Body Design
According to one of the Veyron’s designers, the biggest challenge in creating the Veyron was the aerodynamics.
How do you keep a 250-mph passenger car on the road?
An F-1 car or a Champ car can travel at 250 mph or more, but they have a uniquely designed body, a single driver lying in a reclining position, just an inch or so of ground clearance and an aero-package made up of large wings to generate massive downforce. The Bugatti, on the other hand, is trying to look like a normal car and seat two passengers. The Veyron’s dimensions help to some extent. The car is 79 inches (200 cm) wide, 176 inches (447 cm) long and only 48 inches (122 cm) high. Keep in mind that a Hummer 2 is 81.2 inches wide. The Bugatti is extremely wide for its height. The underside of the Veyron, like an F-1 car, is streamlined and venturi-shaped to increase downforce. There is also a wing in the back of the Veyron (see below) that extends automatically at high speed to increase downforce and keep the car glued to the road. According to Popular Science: Hypercar, “With the moving tail spoiler we’ve got enough downforce now, about 100 kg (221 pounds) at the rear and 80 kg (177 pounds) at the front at top speed.”
The Veyron uses two snorkel-like devices one on either side of the engine to manage airflow. The Veyron has three reasons for managing airflow:
The engine of the Veryon sits behind the driver, so roof-mounted snorkels, the rear-deck vents and side-mounted scoops bring air to the engine and rear brakes.
The size of the engine and transmission, along with the four-wheel-drive system and the four drive shafts, along with the opulence of the passenger compartment (discussed in the next section) and the car’s oversized dimensions, all add weight. Even though the body is sculpted in carbon fiber to minimize its mass, the car weighs in at about 4,300 pounds (1,950 kg). For comparison, a Dodge Viper weighs about 1,000 pounds (454 kg) less.
Even the tires for the Veyron are unique. They’re specially designed by Michelin to handle the stress of driving at 250 mph. The tires need to be sticky like a race car’s and able to handle 1.3 G’s on the skidpad. However, they also need to last longer than the 70 or so miles of a typical race tire.
Michelin therefore created completely new tires to handle the Veyron’s unique requirements. In the rear, the tires are 14.4 inches (36.6 cm) wide. Specifically, the tires measure 245/690 R 520 A front and 365/710 R 540 A rear, where 245 and 365 are the width in millimeters (9.5 and 14.4 inches respectively). The rims are 520 mm and 540 mm in diameter (approximately 20 inches). These tires, in other words, are massive — the rears are the widest ever produced for a passenger car.
The tires use the Michelin PAX system. Their pressure is monitored automatically, and they can run flat for approximately 125 miles (201 km) at 50 mph (80 kph). According to Michelin, the run-flat detection system “plays an integral role in active safety in PAX System. Its role is to inform you of a loss of pressure, either gradual or sudden.” Once warned of an air leak by the PAX system, you can reduce your speed and head toward a tire repair center.
One advantage of the PAX system and its run-flat ability is that it eliminates the need for a spare tire.
The Interior The Veyron seats two in lavish style. The interior is swathed almost completely in leather — the dash, seats, floor and sides are all leather. Only the instruments and a few metal trim pieces interrupt the leather experience.
The car also surrounds its occupants with every sort of electronic nicety, including a remarkable stereo system, navigation system, etc.
Is all of this worth a million bucks? Who knows. But regardless, the Veyron represents a remarkable technological achievement.
The Veyron is also likely to represent the far end of the automotive performance spectrum for some time to come. To create a car much faster will require adding even more weight, and delivering even more power to the wheels. The added weight means diminishing returns in the power-to-weight domain. Additional power means more wheelspin.
Look at a Champ car and consider how radical its appearance is compared to a passenger car. Consider also that a Champ car does not go much faster than the Veyron. The Veyron probably approaches the outer limits of the passenger car envelope, and we are unlikely to see much beyond the Veyron in terms of performance.
This is, in other words, as good as it gets.
Well, here is a video of how fast the Veyron can actually fly.
References: http://en.wikipedia.org/wiki/Bugatti_Veyron
http://auto.howstuffworks.com/bugatti.htm
When entering the site one may wonder of how to post the contents in this site. I will provide a simple step by step instruction of the format in which one should post his/her content. The primary thing which you need to do is just have a quick view into the site to make sure that the content which you are about to post does not already exist, meaning it is not already posted by a third party. After you have confirmed that, go for the following.
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This is how it is done. All these you do will ease the work of the administrator. So kindly stick to these rules and post your content. Happy Posting.
For reference you can have a look at the post which I have included here, iVTEC Engines
VTEC, Variable Valve Timing and Lift Electronic Control is a valve train system developed by Honda to improve the volumetric efficiency of a four-stroke internal combustion engine. This system uses two camshaft profiles and electronically selects between the profiles. It was invented by Honda R&D engineer Ikuo Kajitani. It can be said that VTEC, the original Honda variable valve control system, originated from REV (Revolution-modulated valve control) introduced on the CBR400 in 1983 known as HYPER VT EC. VTEC was the first system of its kind, though other variable valve timing and lift control systems have been produced by other manufacturers (MIVEC from Mitsubishi, VVTL-i from Toyota, VarioCam Plus from Porsche, VVL from Nissan, etc).
i-VTEC
(intelligent-VTEC) introduced continuously variable camshaft phasing on the intake cam of DOHC VTEC engines. The technology first appeared on Honda’s K-series four cylinder engine family in 2001 (2002 in the U.S.). In the United States, Honda first debuted the technology on the 2003 Honda Civic Si EP3 with the economy version.
Valve lift and duration are still limited to distinct low- and high-RPM profiles, but the intake camshaft is now capable of advancing between 25 and 50 degrees (depending upon engine configuration) during operation. Phase changes are implemented by a computer controlled, oil driven adjustable cam gear. Phasing is determined by a combination of engine load and rpm, ranging from fully retarded at idle to somewhat advanced at full throttle and low rpm. The effect is further optimization of torque output, especially at low and midrange RPM.
The K-Series motors have two different types of i-VTEC systems implemented. The first is for the performance motors like in the RSX Type S or the TSX and the other is for economy motors found in the CR-V or Accord. The performance i-VTEC system is basically the same as the DOHC VTEC system of the B16A’s; both intake and exhaust have 3 cam lobes per cylinder. However the valvetrain has the added benefit of roller rockers and continuously variable intake cam timing. Performance i-VTEC is a combination of conventional DOHC VTEC with VTC.
The economy i-VTEC is more like the SOHC VTEC-E in that the intake cam has only two lobes, one very small and one larger, as well as no VTEC on the exhaust cam. The two types of motor are easily distinguishable by the factory rated power output: the performance motors make around 200 hp (150 kW) or more in stock form and the economy motors do not make much more than 160 hp (120 kW) from the factory.
The new SOHC i-VTEC implementation is an entirely new implementation that was introduced on the 2006 Honda Civic’s R-series four cylinder SOHC engines. This implementation uses the so-called “fuel economy cam” and “high output cam” on one of the two intake valves of each cylinder (another intake valve is fixed). The “fuel economy cams” are designed to retard the closure of one intake valve and are activated between 1000-3500RPM and under low load condition. When “fuel economy cams” are activated, the intake valve closes well after the piston has started moving upwards in the compression stroke. During this time, the drive-by-wire throttle valve is open wider than normal. Due to the delayed closing of intake valve, a part of the intake mixture that has entered the combustion chamber is forced out again into the intake manifold. That way, the engine “emulates” a lower displacement than its actual one (its operation is also similar to an Atkinson cycle engine, with uneven compression and combustion strokes), which reduces pumping losses thus reducing fuel consumption and increases its efficiency. VTEC-off on the R18A means it can be considered to be running “high output cams”. When the right conditions are achieved for fuel economy, VTEC engages the 2nd set, the ‘low’ or ‘economy’ cams. Thus VTEC-on on the R18A means it is running low cams.
According to Honda, this measure alone can reduce pumping losses by 16%. Under heavier loads, the engine switches back into its “high output cams”, and it operates like a regular 4 stroke Otto cycle engine. This implementation of i-VTEC was initially introduced in the R18A1 engine found under the bonnet of the 8th generation Civic, with a displacement of 1.8 L and an output of 140 PS (100 kW; 140 hp). Recently, another variant was released, the 2.0 L R20A2 with an output of 150 PS (110 kW; 150 hp), which powers the EUDM version of the all-new CRV. SOHC i-VTEC
With the continued introduction of vastly different i-VTEC systems, one may assume that the term is now a catch-all for creative valve control technologies from Honda.
In 2003, Honda introduced an i-VTEC V6 (an update of the J-series) that includes Honda’s cylinder deactivation technology which closes the valves on one bank of (3) cylinders during light load and low speed (below 80 km/h (50 mph)) operation. The technology was originally introduced to the US on the Honda Odyssey minivan, and can now be found on the Honda Accord Hybrid, the 2006 Honda Pilot, and the 2008 Honda Accord.
i-VTEC VCM was also used in 1.3L 4-cylinder engines used in Honda Civic Hybrid.
It is a version of i-VTEC with direct injection.
It was first used in 2003 Honda Stream.
This is how an ivtec engine works
And this is the Honda Hybrid System
Reference: www.wikipedia.org
www.world.honda.com
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Our site is fast growing but many of you may wonder of what to post in this site that you have so much to choose from. In order to avoid confusion I would like to provide you a small list of items that would give you some idea related to posting in this site. Here you can post
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Our objective with the 5-stroke engine is to develop a gasoline engine with fuel consumption and emission levels comparable to that of current diesel engines, without the serious problem of particulate and NOx emissions that plague diesels.
The engine concept, which was invented by Gerhard Schmitz, has been developed by Ilmor into a working engine using a rapid prototype cast cylinder head, a machined from solid cylinder block and separate electrically powered oil and water pumps. Two overhead camshafts operate the conventional coil spring valvegear with the HP camshaft running at 0.5 x crank speed and the LP camshaft running at 1 x crank speed. The engine is also turbocharged to increase the engine rating.
Principle of operation
The 5-stroke concept engine utilizes two fired cylinders (High Pressure – HP) operating on a conventional 4-stroke cycle which alternately exhaust into a central expansion cylinder (Low Pressure – LP), whereupon the burnt gases perform further work. The LP cylinder decouples the expansion and compression processes and enables the optimum expansion ratio to be selected independently of the compression ratio.
Running of the concept engine has produced impressive fuel consumption readings over a very wide operating range. This is because at the onset of knock a greater percentage of work can be extracted in the LP cylinder, giving a degree of self compensation.
Further development
Having run the proof of concept engine, Ilmor is now looking to produce a second phase development engine for in-vehicle testing. The performance targets for this engine are as follows:
Advantages of the 5-stroke concept
5-stroke performance figures
Ilmor is using its race engine expertise to bring developments to the field of energy efficient engines. Motor racing is not generally associated with fuel economy, but the lessons learned during periods of intense engine development can be applied with great effect to create highly fuel efficient engines.
Fuel efficiency can be improved by downsizing engines – creating the same amount of power from a smaller swept volume (smaller capacity) which typically burns a smaller amount of fuel. High performance engine design is all about extracting as much power as possible from a defined capacity by the use of intelligent design, low friction coatings or even completely new concepts. All of this knowledge can therefore be applied to maximise the power output of a small capacity, fuel efficient engine.
Our flexible approach ensures that we are able to build on a concept and develop innovative, tailored and most importantly working solutions for our clients, allowing physical testing and ongoing development of the concept.
5-stroke concept engine
One such example of this application of our engineering knowledge is the patented 5-stroke engine which Ilmor is currently developing. Our objective with the 5-stroke engine is to develop a gasoline engine with fuel consumption and emission levels comparable to that of current diesel engines, without the serious problem of particulate and NOx emissions that plague diesels.
The simplest way to demonstrate the 5-stroke principle was considered to be a 3 cylinder layout with two fired 4-stroke cylinders (High Pressure – HP) alternately exhausting into a central expansion cylinder (Low Pressure – LP) which provides a further expansion process on the exhaust gases (the 5th stroke).
The engine uses a rapid prototype cast cylinder head, a machined from solid cylinder block and separate electrically powered oil and water pumps. Two overhead camshafts operate the conventional coil spring valvegear with the HP camshaft running at 0.5 x crank speed and the LP camshaft running at 1 x crank speed. The engine is also turbocharged to increase the engine rating.
Reference: www.ilmor.co.uk
Fuel efficiency and power are two goals high in any engineer’s criteria; they also happen to be important to any customer. The down side is that they are usually at cross-purposes where one goal (fuel efficiency for instance) must be sacrificed for the other (power). Unfortunately, it’s a compromise we’re all too painfully aware of in our quest for performance.
“The design goal is pretty simple, we wanted to take the 5.3L V8 and make it more efficient. We wanted the customer to have the same characteristics of throttle response, power, general performance and towing capability that we had with the original LM7–and provide the customer with a more fuel-efficient package.” – GM Engines division manager.
What GM Powertrain came up with the 5.3L Engine is almost identical to the outgoing Engines on the surface, but technologically advanced on the inside. That technology enables cylinder deactivation (called displacement-on-demand or “DOD” by GM insiders) during periods of low load demand and is the source of the increased efficiency mentioned earlier. There are a couple of areas to attack to make an internal combustion engine more efficient. These areas are mechanical efficiency, pumping losses, and unused heat energy. Area of pumping losses are relatively easy to attack and overcome with the displacement-on-demand system. That’s the area this system addresses.
Pumping losses represent the work needed to bring a fresh charge into the combustion chamber and to expel the products of combustion. Some tools that can simulate the vehicle performance characteristics relative to fuel economy. When looked at mid-sized utility vehicles, its seen that it could achieve about an 8 percent increase in vehicle fuel economy.
All corporate politics aside, the engineers at GM Powertrain have designed yet another mechanical marvel, and it’s all due to some remarkably modest changes to the very robust Gen III architecture on which the Gen IV is based. The new DOD-specific hardware includes two-stage switching lifters, a lifter oil manifold assembly (located in the valley of the engine), a redesigned lube circuit and oil pump, electronic throttle-by-wire operation, a pressure-activated muffler valve, and an improved E40 engine controller running DOD-specific software.
In order to eliminate the pumping losses you need to disable both the intake and exhaust valve. This results in a completely sealed, deactivated cylinder, which is essentially an air spring being acted upon by a piston. Virtually all the work put into it during compression is returned to the crank during decompression, finally giving credence to the old joke about piston-return springs.
Currently, we could disable just the fuel delivery but the valves would still be opening and closing and each cylinder would still be doing work pumping air in and out. So there would be no net gain in efficiency–you wouldn’t have eliminated the pumping losses at all.
In support of cylinder deactivation is some very interesting choreography from things ranging from throttle valve modulation to active exhaust tuning, but it all starts with the additional job tasked to the lifters. Valves are disabled through a device called a switching lifter. This differs from a normal lifter in that there is an inner body and an outer body connected by a spring-loaded pin. For V-8 operation, the pin is fully expanded by the spring so the two pieces act as one and the lifter acts like a regular lifter. When we want to disable the valve operation, we deliver high-pressure oil to a groove in the lifter that leads to the outside end of the pin, forcing the pin to collapse the spring. Now the two parts of the lifter are free to move relative to one another and as the cam lobe pushes on the follower the inner portion of the lifter pushes against another spring at the top of the lifter and does not transfer force to the pushrod.
A look at the lifter cross-section reveals an elegant, yet simple design that has the potential to change the way we think about traditional pushrod engines. In order for the switching lifter to work effectively, the engine needed a redesigned oiling system. Both iron and aluminum versions of the engine block have redesigned oil galleries to support DOD oiling requirements. Those oil galleries are supplied by a lifter oil manifold assembly (LOMA) located in the lifter valley of the engine. Under cylinder deactivation, the LOMA routes oil to the applicable lifters by means of four lifter oil solenoids, which are controlled by an engine management controller. To supply the additional needs of the cylinder deactivation circuit, a higher capacity oil pump is fitted.
Since DOD relies on the use of electronic throttle control, the throttle body is not interchangeable with earlier cable-actuated throttle bodies. In concert with these DOD-specific changes, an improved coil-on-plug ignition system (which requires less energy), a returnless fuel system, and uprated cylinder head (minus the hollow sodium-filled valves) have been employed.
The key part of DoD that makes the transition imperceptible is electronic throttle control. Once the computer determines operating conditions are met to enable DOD, it uses engine vacuum as an indicator of customer power demand. When the computer decides to disable four cylinders, it calculates where the throttle needs to go such that the torque will be equal when you end up with four cylinders.
With the different modes of cylinder deactivation, there was a dramatic change in NVH, and a corresponding difference in throttle response and exhaust tone. All of these were deemed unacceptable in a luxury car, and at the end of the day, the improved vehicle economy wasn’t capable of offsetting the loss of comfort and power.
The transition from eight-cylinder operation to four-cylinder operation is aided by electronic throttle control (ETC). At no time does the driver perceive a decrease in engine power when in V-4 mode because ETC applies a seamless increase in manifold pressure. (Translation: when the engine switches to four cylinders, your foot is still pressed the same amount on the gas pedal because the computer has opened the throttle more without you knowing it.) An increase in power demand is just as smooth; there is no dramatic surge in power during transition to V-8 operation beyond what is expected, that’s because the ETC closes the throttle in conjunction with cylinder activation.
One area of dissatisfaction was the transition feel when going from four to six to eight, or from eight to six to four cylinders. The reason that electronic throttle control helps that is that we are able to move the throttle with the computer, not the pedal. The computer moves the throttle blade without the customer knowing it. So the engine torque is the same on both sides of the transition event. You don’t want the customer to know this transition has occurred.
In order for the customer to truly buy into the concept of DOD, it must be absolutely undetectable. Even with ETC and tuned engine mounts, there was a distinct difference in exhaust tone between V-4 and V-8 operation. To mitigate this difference, a pressure-activated valve in the muffler adjusts the exhaust path to deliver an appropriate amount of noise reduction. It was found that such an exhaust system had packaging limitations that precluded its use in the Buick Ranier, which has a shorter wheelbase than the vehicles currently slated to receive DOD.
Lifter design and pushrod length are the same for all eight cylinders, but camshaft lobe profiles are different for the cylinders, which are deactivated. In displacement-on-demand equipped engines, half of the cylinders have unique two-piece valve lifters.
It’s important to know that the switching lifter has a lift limitation of 15mm. The factory cam uses 12.2mm of that (about .480 inch), giving a theoretical valve lift limit of .590 inch. It’s worth noting that this limit is for the lifter; a different valve spring would almost surely have to be used at this valve lift. Interestingly, it seems possible to grind a custom camshaft, which would only provide increased lift and duration to the non-DOD cylinders (2, 3, 5 and 8), thus allowing higher lift with standard non-switching lifters in those cylinders.
With four cylinders working the entire life of the engine and four cylinders working for approximately half that time, is there any extra maintenance or any deviation of maintenance from a normal V-8? The service life of the engine will be the same as normal current engines. There are a couple of reasons for not making the service requirement any different for these four cylinders. One would be to avoid any confusion; the second, quite frankly, is that it’s not necessary.
DOD JUNIOR
The “high value” 60-degree OHV V-6, ie the DoD Junior Engines, will become the staple engine in vehicles which typically had the old 3100-, 3400- and more recent 3500-series engines.
The DoD Junior will have electronic throttle control and cylinder deactivation (running on three cylinders), but will also throw into the mix variable valve timing and a variable intake manifold for dynamic runner tuning. Variable valve timing will be accomplished electronically by a gear-driven camshaft phaser capable of altering timing by as much as 40 degrees. This feature will also allow the elimination of EGR control.
Reference: http://www.superchevy.com/technical/engines_drivetrain/accessories_electronics/0405sc_gmdod/index.html
In describing GM’s new fourth-generation small-block, we run the risk of sounding like that popular light beer commercial, “tastes great, less filling!” As silly as it sounds, the technology packed into GM’s new Gen IV powerplant does allow one to have his proverbial cake and eat it too. Fuel efficiency and power are two goals high in any engineer’s criteria; they also happen to be important to GM’s customers. The down side is that they are usually at cross-purposes where one goal (fuel efficiency for instance) must be sacrificed for the other (power). Unfortunately, it’s a compromise we’re all too painfully aware of in our quest for performance.
We recently got a chance to sit down with Chris Meagher, assistant chief engineer of small-block truck engines at GM. And while we were initially intent on milking every last bit of information concerning the Corvette’s new 400-hp LS2, we quickly realized that the real technology party is happening in the more utilitarian 5.3L version know as the LH6. As it so happens, the LS2 is a subtle evolution of the LS1, so we’ll let the other magazines focus on it and we’ll concentrate on the much-anticipated displacement-on-demand technology, which has managed to pass the LS2 by.
In our brief one-hour interview, we learned a lot about what the future of hot rodding will look like. In some respects, it looks very similar to what we’ve seen with the Gen III LS1 and LS6 engines, but in other ways, it’s an evolutionary leap forward. Chris Meagher explained the impetus behind the redesign: “The design goal is pretty simple, we wanted to take the 5.3L V8 and make it more efficient. We wanted the customer to have the same characteristics of throttle response, power, general performance and towing capability that we had with the original LM7–and provide the customer with a more fuel-efficient package.”
What GM Powertrain came up with–the 5.3L LH6–is almost identical to the outgoing LM7 on the surface, but technologically advanced on the inside. That technology enables cylinder deactivation (called displacement-on-demand or “DOD” by GM insiders) during periods of low load demand and is the source of the increased efficiency mentioned earlier. “We know that there are a couple of areas that we can attack to make an internal combustion engine more efficient,” says Meagher. “These areas are mechanical efficiency, pumping losses, and unused heat energy. We knew that we could attack the area of pumping losses relatively easily with our displacement-on-demand system. That’s the area this system addresses.”
While typical hot rodding tricks revolve around making the engine bigger or getting more air and fuel inside an engine, the engineer working for the factory can’t always afford the luxury of this approach. The working principle from the engineer’s point of view is that the power available is what’s left over after you take away everything else that robs power, such as friction and pumping losses. Meagher explains: “Pumping losses represent the work needed to bring a fresh charge into the combustion chamber and to expel the products of combustion. We have some tools that can simulate the vehicle performance characteristics relative to fuel economy. When we looked at mid-sized utility vehicles, we saw that we could achieve about an 8 percent increase in vehicle fuel economy.”
To an engineer, eight percent is a huge improvement. At the gas pump or on the dyno, it’s also a huge improvement. “Displacement-on-demand is a win-win for drivers who rely on the power of the small-block V-8 and are conscious about fuel economy. The implications of this technology are tremendous,” says Meagher. For now at least, those implications will be exclusive to three vehicles, the 2005 Chevy TrailBlazer EXT, the GMC Envoy XL and Envoy XUV. But before moving on to the nuts and bolts of DOD, we’d like to point out that it has far-reaching possibilities for performance enthusiasts. Had GM elected to apply DOD technology to performance vehicles such as the Corvette, GTO or a future Camaro, there would be far less pressure from corporate average fuel economy (CAFE) to import sub-compacts from outside GM as is the case now.
The bottom line is, DOD on more cars could mean more–and better–choices for enthusiasts. As an example, an early prototype C6 Corvette with an LS2 running DOD provided equal power and acceleration to an LS2 without DOD, but produced 35 mpg instead of 30 mpg. When applied over a large volume of vehicles, GM could have the choice to pocket the improvement in economy and reduce the need to import small outside-sourced cars, or it could build a larger V-8 with more power (say a 6.5L V-8 with 430hp) and keep the same 30 mpg. In the end, for reasons not entirely understood by us but conceivably related to exhaust packaging, DOD technology did not make it into the C6 Corvette, GTO, CTSv or any other performance application as we had hoped. One thing Meagher did share with PHR is that the goal of DOD (on the limited range of SUVs currently planned) is to allow additional vehicle mass (in the form of increased content) without a commensurate decrease in fuel economy or performance.
“In order to eliminate the pumping losses,” says Meagher, “you need to disable both the intake and exhaust valve.” This results in a completely sealed, deactivated cylinder, which is essentially an air spring being acted upon by a piston. Virtually all the work put into it during compression is returned to the crank during decompression, finally giving credence to the old joke about piston-return springs. (That’s nothing. Wait ’til you hear about the muffler valve…)
“Currently, we could disable just the fuel delivery,” says Meagher, “but the valves would still be opening and closing and each cylinder would still be doing work pumping air in and out. So there would be no net gain in efficiency–you wouldn’t have eliminated the pumping losses at all.”
In support of cylinder deactivation is some very interesting choreography from things ranging from throttle valve modulation to active exhaust tuning, but it all starts with the additional job tasked to the lifters. “We disable the valves through a device called a switching lifter,” explains Meagher. “This differs from a normal lifter in that there is an inner body and an outer body connected by a spring-loaded pin. For V-8 operation, the pin is fully expanded by the spring so the two pieces act as one and the lifter acts like a regular lifter. When we want to disable the valve operation, we deliver high-pressure oil to a groove in the lifter that leads to the outside end of the pin, forcing the pin to collapse the spring. Now the two parts of the lifter are free to move relative to one another and as the cam lobe pushes on the follower the inner portion of the lifter pushes against another spring at the top of the lifter and does not transfer force to the pushrod.”
A look at the lifter cross-section reveals an elegant, yet simple design that has the potential to change the way we think about traditional pushrod engines. (Ironically, when DOD is working, it hinges on lifters that do not lift! Something we never thought we’d ever want.) In order for the switching lifter to work effectively, the engine needed a redesigned oiling system. Both iron and aluminum versions of the engine block have redesigned oil galleries to support DOD oiling requirements. Those oil galleries are supplied by a lifter oil manifold assembly (LOMA) located in the lifter valley of the engine. Under cylinder deactivation, the LOMA routes oil to the applicable lifters by means of four lifter oil solenoids, which are controlled by a new E40 engine management controller. To supply the additional needs of the cylinder deactivation circuit, a higher capacity oil pump is fitted to the LH6 engine.
For the most part, the Gen IV engine family is very similar to the Gen III (LS1, LS6, LM7, LQ4, LQ9, etc.). Although the two are externally similar, there are several significant differences, which impede the interchangeability of some parts between Gen III and Gen IV engines. For one thing, the real estate required by the LOMA and its attendant electronics forced the relocation of the knock sensors and the camshaft position sensor. Since DOD relies on the use of electronic throttle control, the throttle body is not interchangeable with earlier cable-actuated throttle bodies. In concert with these DOD-specific changes, an improved coil-on-plug ignition system (which requires less energy), a returnless fuel system, and uprated LS6 cylinder heads (minus the hollow sodium-filled valves) have been employed. Fortunately, the cylinder heads do retain interchangeability between Gen III and Gen IV, which could prove to be a boon to older LS1s.
Readers who remember the 1980s will recall this isn’t GM’s first rodeo with cylinder deactivation. That first happened at Cadillac with the 8-6-4 engine, which was roundly criticized for its service record and its poor vibration (NVH) characteristics. The old adage of once bitten, twice shy applies here not only to potential LH6 customers, but also to the folks at GM working to make Gen IV the best engine architecture yet. GM’s Meagher quickly points out the lessons learned: “I worked on the V-8-6-4 earlier in my career and [the LH6 is] the same idea. The key difference is the control system configuration. The key part of it that makes the transition imperceptible is electronic throttle control. Once the computer determines operating conditions are met to enable DOD, it uses engine vacuum as an indicator of customer power demand. When the computer decides to disable four cylinders, it calculates where the throttle needs to go such that the torque will be equal when you end up with four cylinders.”
With the different modes of cylinder deactivation in the Cadillac 8-6-4, there was a dramatic change in NVH, and a corresponding difference in throttle response and exhaust tone. All of these were deemed unacceptable in a luxury car, and at the end of the day, the improved vehicle economy wasn’t capable of offsetting the loss of comfort and power. In one sense, the failure of the Cadillac was a windfall to DOD engineers because the design obstacles had been clearly defined years ago.
In the LH6, the transition from eight-cylinder operation to four-cylinder operation is aided by electronic throttle control (ETC). At no time does the driver perceive a decrease in engine power when in V-4 mode because ETC applies a seamless increase in manifold pressure. (Translation: when the engine switches to four cylinders, your foot is still pressed the same amount on the gas pedal because the computer has opened the throttle more without you knowing it.) An increase in power demand is just as smooth; there is no dramatic surge in power during transition to V-8 operation beyond what is expected, that’s because the ETC closes the throttle in conjunction with cylinder activation.
Meagher told PHR: “One area of dissatisfaction [with the Cadillac] was the transition feel when going from four to six to eight, or from eight to six to four cylinders. The reason that electronic throttle control helps that is that we are able to move the throttle with the computer, not the pedal. The computer moves the throttle blade without the customer knowing it. So the engine torque is the same on both sides of the transition event. You don’t want the customer to know this transition has occurred.”
As a side note, the LH6 does not employ a six-cylinder mode due to the unique vibration associated with it. One of the greatest complaints with the Cadillac was the excessive NVH in V-6 mode, a problem that has been completely avoided by transitioning directly between V-4 and V-8 modes. Nevertheless, GM Powertrain has designed tuned engine mounts for multiphase engine operation. The idea is that if a customer doesn’t look at the window sticker, he will never know he has DOD in his vehicle.
In our interview with Chris, we remembered that there was one other mid-sized utility in the GM stable, which uses a 5.3L V-8, the Buick Ranier. That vehicle is not slated for DOD, although it will have the new LH6 engine (minus DOD). Chris’s explanation for the exclusion of DOD in the Buick Ranier is too long to print here, but is worth a condensed look in light of the next point we need to make. GM deemed that in order for the customer to truly buy into the concept of DOD, it must be absolutely undetectable. Even with ETC and tuned engine mounts, there was a distinct difference in exhaust tone between V-4 and V-8 operation. To mitigate this difference, a pressure-activated valve in the muffler adjusts the exhaust path to deliver an appropriate amount of noise reduction. It was found that such an exhaust system had packaging limitations that precluded its use in the Buick Ranier, which has a shorter wheelbase than the vehicles currently slated to receive DOD.
Fortunately, The Ranier and any other non-DOD applications currently getting a 5.3L LM7 will still benefit from the non-DOD version of the LH6, which will replace the LM7. The LH6’s freer-flowing LS6 cylinder heads, oiling system upgrades and ignition system upgrades beat the outgoing LM7 to deliver 290hp and 325 lb.-ft. of torque (in both DOD and non-DOD form). It’s also worth noting that the upgrade to LS6 heads required a new piston to meet program requirements for compression and power. Strangely enough, that leaves only the GTO in the GM V-8 line-up as having the older, lesser-flowing heads of the LS1 (since LQ4, LQ9, LS6, LH6 and LS2 all have some variant of the improved LS6 head). GM, can we have the LS6 head for the GTO in the 2005 model?
Operationally, the LH6 always deactivates the same four cylinders in the firing order (1, 4, 6 and 7). According to Meaghan, lifter design and pushrod length are the same for all eight cylinders, but camshaft lobe profiles are different for the cylinders, which are deactivated. (This seems, in part, to contradict the GM media website, which states, “…in displacement-on-demand equipped engines, half of the cylinders have unique two-piece valve lifters…” -this being an important stipulation for those wanting to swap camshafts.)
For hot rodders wanting to modify their DOD-equipped LH6s, it’s important to know that the switching lifter has a lift limitation of 15mm (at the valve). The factory cam uses 12.2mm of that (about .480 inch), giving the LH6 a theoretical valve lift limit of .590 inch. It’s worth noting that this limit is for the lifter; a different valve spring would almost surely have to be used at this valve lift. Interestingly, it seems possible to grind a custom camshaft, which would only provide increased lift and duration to the non-DOD cylinders (2, 3, 5 and 8), thus allowing higher lift with standard non-switching lifters in those cylinders.
Before our interview ended, we asked one final question of Meagher: With four cylinders working the entire life of the engine and four cylinders working for approximately half that time, is there any extra maintenance or any deviation of maintenance from a normal V-8? To that Meagher says: “The service life of the engine will be the same as normal current engines. There are a couple of reasons for not making the service requirement any different for these four cylinders. One would be to avoid any confusion; the second, quite frankly, is that it’s not necessary.”
PHR would like to thank Tom Read of GM product communications for arranging the interview with Chris Meagher.
The LH6 isn’t the only engine that will receive the benefits of displacement-on-demand. We’ve already mentioned that Daimler-Chrysler’s Hemi will be getting some form of DOD in the near future–but we don’t have exact details of that yet. What we do know is that GM is coming out with a 3.9L V-6 (RPO code LZ8) which is scheduled to first appear in the 2005 Pontiac G6.
The “high value” 60-degree OHV V-6 will become the staple engine in vehicles which typically had the old 3100-, 3400- and more recent 3500-series engines (on which the LZ8 is based). Rated at 240hp at 5900 rpm and 245 lb.-ft. of torque at 2800 rpm, the 9.8:1 compression LZ8 will make 90 percent of its peak torque between 1800 and 5800 rpm. That compares very favorably with the venerable supercharged 3800 (RPO L67) which, in most iterations, makes 240hp at 5,200 rpm. What’s more, the LZ8 does it with only 100cc more displacement, two valves per cylinder, pushrods and no supercharger.
Like the LH6, the LZ8 will have electronic throttle control and cylinder deactivation (running on three cylinders to the LH6’s four), but will also throw into the mix variable valve timing and a variable intake manifold for dynamic runner tuning. Variable valve timing will be accomplished electronically by a gear-driven camshaft phaser capable of altering timing by as much as 40 degrees. As a happy coincidence, this feature will also allow the elimination of EGR control.
For the time being, the LZ8 will only be available in non-DOD form, but we’ve been assured that it will eventually appear. What’s more, the LZ8 is designed to work in a rear-wheel drive configuration, which would pave the way for its use in a future base-model Camaro. If that occurs, the LZ8 would trump the ‘05 Mustang’s base V-6 by nearly 40 horsepower while returning the same fuel economy.
