Garrett Turbo

Lauren Woods asked:


German carmaker Volkswagen is known for its precision engineered cars and the performance that they bring to the table. One of the cars in Volkswagen’s lineup which gives any driver a thrilling ride is the Fahrenheit. For the 2008 model year, Volkswagen has made the Fahrenheit even more appealing and more powerful.

The 2008 Fahrenheit will be equipped with a 2.0-liter turbocharged four-cylinder engine. This same engine is also being used by other vehicles from Volkswagen and Audi. The turbocharged engine provides power when needed without the lag that is commonly encountered on turbocharged engine.

The lag happens because turbochargers are powered by exhaust gases. When a turbocharged engine is of course just starting up, the amount of exhaust gases is not enough to power the turbine of the turbocharger. But with the engine on the Fahrenheit, the design has been carefully adjusted to make sure that lag is minimal.

The said engine can produce as much as 200 horsepower and 207 pound foot of torque. The combination of the horsepower and the twisting force gives the Fahrenheit a good acceleration.

In terms of stability, the suspension setting of the Fahrenheit is designed for sports cars. With that suspension, although the ride is stiff, the car can navigate sharp corners on high speeds. With aftermarket parts such as Volkswagen cold air intake, the power can be increased and the increased power will go well with the sports-tuned suspension.

The engine is paired with a six-speed transmission which has close gear ratios which provides smooth transfer of power from the engine to the drive wheels. The precision engineered transmission works well with the engine that clashing gears inside the gearbox does not send vibrations to the body of the car.

Stopping power is provided by disc brakes for the front and the rear. For the front wheels, the Fahrenheit is equipped with 12.3-inch discs while for the rear; it is equipped with 11.3-inch disc brakes. Stopping power though is not as responsive as the engine. According to some auto journalists, the brakes only activated when the brake pedal is pushed almost to the floor.

The Fahrenheit is a limited edition vehicle which means that one would not be able to see it on a regular basis cruising around city streets. The theme used by Volkswagen on the limited edition Fahrenheit is yellow. Exterior color is yellow which makes it call for attention. The interior of the Fahrenheit is also accented with the color yellow. Although the color and its use inside and out of the Fahrenheit maybe attractive, it will not be for everyone.

According to the German car manufacturer, the limited edition Fahrenheit will have a starting price of $27,880 for the model with the six-speed manual transmission. This is aimed at performance enthusiasts who are more favorable with manual shifting than automatic ones.

The addition of the yellow Fahrenheit in Volkswagen’s lineup for the 2008 model year is expected to turn heads. Performance enthusiasts are expected to take notice, but with the color yellow plastered all over the vehicle, it is guaranteed to attract attention of the general public.



Nash

Mac Demere asked:


rs are traditionally rear-wheel drive. As is the 2010 Hyundai Genesis Coupe. Similar to a RWD racer, the Genesis Coupe 2.0T model is quick, responsive and fast. The standard engine is a 210-hp, turbocharged, four that makes a whopping 230 pound-feet of torque at a very low 2,000 rpm. Pricing for the 2010 Hyundai Genesis Coupe 2.0T is under $25,000.

The main purpose of front-wheel-drive, contrary to popular misconception, is to increase interior room. (And, if you haven’t heard, additional weight is not “road hugging.”) With a front-drive car, the front tires must do all of the acceleration and steering and about 80 percent of the braking, while the rear tires’ main job is to keep the gas tank from dragging on the pavement. This means a front-driver has more difficulty simultaneously accelerating and turning (or turning and braking). With a rear-drive car, the rear tires concentrate on putting power to the ground, while the fronts focus on turning and/or slowing down. The bottom line: A rear-drive car will always beat an otherwise identical front-driver around a dry racetrack or up a mountain road. Not to mention, a rear-wheel-drive car can do things no stock front-drive car can do: drifting powerslides and hooning, smoky burnouts. (”Hoon” is an Australian or New Zealand word translates to anti-social behavior and driving irresponsibly.)

The Genesis Coupe is also available with a 306-horsepower 3.8-liter V6. While the Genesis Coupe 3.8 V6 is notably quicker at the drag strip, the turbo four is the more enjoyable version of the car. Reasons are many: Much of the V6’s extra 100 pounds is carried on the nose, which tends to overwhelm the front tires. The four also has much lower first and second gears in its six-speed manual transmission. The combination of big torque and low gearing gives the four cylinder strong acceleration in the speed range that can be used on public roads without entering the Highway Patrol’s Frequent Offender Program. It also offers enough torque to squeal the tires leaving the line and on the one-two upshift.

The V6 moves the Genesis Coupe into a different realm. The V6 feels much less nimble than the four. Also, the V6’s manual did not react well to performance-oriented shifts, responding with harsh drivetrain shocks, as if we had never driven a manual. Also, the linkage of both manual transmissions suffered from an extremely annoying buzzing. Unfortunately, we did not have the opportunity to sample either of the automatics: five-speed with the four or six-speed on the V6.

The Genesis Coupe 2.0T will go head-to-head with the likes of the Honda Civic Si and the V6 Ford Mustang. The four-cylinder turbo is rated at 30 miles per gallon in the government’s highway driving cycle and 21 mpg. The V6 gets 26 mpg on the highway and 17 mpg in the city, when equipped with the six-speed automatic.

Both engines are available in a “Track” configuration, which includes 19-inch-diameter wheels with very sticky Bridgestone Potenza RE050A summer tires and stiffer suspension springs and anti-roll bars, as well as Brembo brakes. The summer tires will help the Coupe’s street performance but the stiffer suspension will be difficult to live with every day in pothole-plagued areas. Unless you’re really going to the track, stick with the regular model. There’s also a “R” version that removes some standard features, such as the sunroof, to reduce weight.

Safety features include six airbags, active head restraints, standard electronic stability control and anti-lock brakes. Included is a 360-Watt, 10-speaker Infinity sound system. Inside, the Genesis Coupe offers good quality materials and commendable fit and finish. This is one reason that the average residual value after 36 months for a Hyundai has improved to about 43 percent currently from 37 percent in 2005. All is not perfect as the blue on black digital information center is difficult to read, and the speedometer and tachometer are offset away from the center of vision, making them a bit difficult to follow.

The Genesis offers minimal rear seat room. Five 17-year-old girls would fit just fine, but the Genesis Coupe is a two-seater for big or tall adults. It has a hefty trunk with a pass-through for long items. Here’s the take-away: Rear-drive rules. Strong horsepower, low gearing and a low purchase are nice, too.

James Flammang asked:

making their redesigned debut for 2007, the current-generation coupes were “redesignated” for 2009, topped by the new 335i xDrive coupe with all-wheel drive and a 300-horsepower, twin-turbocharged 3.0-liter six-cylinder engine. This is BMW’s first twin-turbo inline six. In fact, turbocharging has not been used on BMWs since the 1980s, when it appeared on a handful of models.

Engineers decided to revive turbocharging, because of recent technical developments. Relatively small turbochargers minimize the dreaded “turbo lag,” since they build up pressure much faster than does a single, larger unit. BMW also offers a 328i coupe with a 230-hp, naturally aspirated 3.0-liter six-cylinder that uses magnesium-aluminum construction. Transmission choices for both include a standard six-speed manual gearbox, or an available six-speed Steptronic automatic.

Each model is offered with xDrive, which is BMW’s version of all-wheel drive. On smooth, dry roads, xDrive delivers what BMW calls a “sporty, rear-wheel-drive feel,” which is precisely what most shoppers are seeking. Along wet or snow-packed roads, on the other hand, xDrive “automatically sends more torque to the axle with more traction,” promising helpful front/rear weight balance. Making iDrive an option lets those who favor high-tech control select that unit, but allows those who prefer a simpler, traditional configuration to omit the love-it/hate-it system.

Headlight design, taillamp detailing, outside mirrors and interior appearance were created specifically for coupes. Two-doors feature a long wheelbase, short overhangs, a setback passenger compartment, and a low, sleek roofline. The long hood reflects BMW’s tradition of inline six-cylinder engines. Corona light rings that serve as BMW-distinctive daytime running lights accent the standard xenon adaptive headlights.

Rear occupants in the four-passenger coupes have a center console between individual seats with separate storage boxes, additional air outlet vents, and footwell lights. Standard leatherette upholstery comes in Black or Cream Beige, with leather optional. BMW’s iDrive controller is an option, too. One helpful feature is the seatbelt feeder arm, which automatically moves forward, presenting the seatbelt to the driver and front passenger when doors are closed and the key inserted. Access to rear seats has been made easier, according to BMW, but it’s still a chore for the less agile.

There’s nothing the least bit gaudy or garish about a 3 Series coupe, which relies strictly upon clean lines and smooth curves to establish its presence. Performance is precisely as energetic as expected from BMW. The twin-turbo engine has all the go-power anyone will need, available in an instant. In typical BMW form, the manual gearbox shifts with ease and finesse, requiring a mere flick of the wrist. Adeptly matched to the gearbox, BMW’s clutch engages with smooth confidence.

Engineers have given the 335i a surprisingly comfortable ride, considering the coupe’s impressive level of road-hugging expertise. Rear-drive 3 Series coupes are well known for their sure-footed behavior, but xDrive adds an extra helping of assurance. Ordinarily, there’s no evidence of its existence apart from a badge on the fender. When the pavement turns wet or slick, however, it’s ready to take action as needed.

Only a light rumble can be heard from the twin exhaust pipes. Otherwise, the 335i is fairly quiet. Steering feel and response don’t get much better, or more satisfying. Particularly comfortable front seats provide sufficient space all around, though the front compartment is a bit on the snug side.

Prices start at $38,125 (including destination charge) for a 328i coupe with rear-wheel drive. For a 335xi coupe with the twin-turbo engine and all-wheel drive, the outlay escalates to $44,625. An automatic transmission adds $1,325. Additional options include Active Cruise Control, rear Park Distance Control, a navigation system, heated front seats, an iPod/USB adapter, and a Premium or Sport Package (including upgraded tires).

Mason

Haitham Alhumsi asked:


The first time I ever heard of twin charging (using both a turbocharger and a supercharger on the same motor) was probably back in year 2000. At that time I was very interested in performance for the Toyota Celica and naturally I also read a lot about its sister cars (that shared some of the same engines) such as the Camry and the MR2.

One of the most interesting aftermarket parts I ran across at the time was the HKS turbo kit for the 4AGZE powered 1st generation mr2. The 4agze (for those that are not familiar with Toyota engines) is a peppy 170 horsepower 1.6 liter engine powered by the Toyota SC-12 roots type supercharger. On this car Toyota used an electromagnetically clutched supercharger that could be disabled during low power requirements such as cruising, and engaged when the user demands it.

One of the most important parts of the HKS kit is the bypass valve. This valve was used to direct air from the supercharger to the engine at lower rpm/flow points. Once the rpm’s rise, and the engine starts to demand more air, and the turbocharger is fully spooled, the valve switches over gradually till the turbocharger alone is feeding the engine while the supercharger is completely bypassed. The twin-charged MR2’s were rumored to break the 300hp mark in some cases, depending on the final boost level and the supporting modifications, and this level of power for a 1.6 litre motor at the time was quiet astounding.

The theory behind this kind of system is to use a small positive displacement (roots style) supercharger. Supercharger performance efficiency is typically at its highest at lower engine and supercharger rpm’s (for example from idle to 4000 rpm’s). Above 4000 rpm’s the supercharger’s performance and efficiency starts to drop, the horsepower required to drive it starts to rise exponentially, and the air temperature coming out of the supercharger starts to rise dramatically limiting performance.

On the other hand, using a generously sized turbocharger will allow us to feed the engine efficiently with cooler air (than that from an overworked supercharger) and maintain high rpm performance. The problem with using a larger turbocharger is that a generously sized turbocharger typically doesn’t spool before 3000 to 4000 rpm’s giving us a limited power band and thus providing no performance boost at lower rpm’s.

The idea of twin charging is to use both a supercharger and a turbocharger to have each charger do what it does best, have the supercharger boost the motor for low end torque, and as it runs out of steam, the turbocharger comes online to carry us through to redline.

There are three aspects to these types of systems that make them prohibitive to most tuners:

1. Cost and complexity: Having a complete supercharger system as well as a complete turbocharger system on the same vehicle is a lot of money to spend and a lot of parts to deal with and diagnose in case something does go wrong.

2. The bypass valve used to bypass the supercharger (and yet hold in all the air pressure coming from the turbocharger) as well as being able to control this valve electrically or mechanically requires a custom made one off valve that isn’t quite available off the shelf. Although as I write this it seems possible to find a large sized dual chamber bypass valve plumbed to operate on the differential pressure between the turbo outlet and the supercharger outlet to switchover once the turbocharger pressure = the supercharger pressure + the tension of the bypass valve opening mechanism.

3. Since we are using two different types of chargers with two different efficiency maps, it can get very complicated to figure out how to tune the motor (especially with much simpler fuel injection systems that were used at the time) because the air density can vary dramatically at the same rpm point and pressure level depending on which charger is feeding air to the motor and at what proportion. This is also where the HKS turbo kit for the 4agze was at its weakest, namely at smoothing the transition point fueling between the supercharger to turbocharger switchover.

One of the things that has changed over the last 10 years is the availability (and proliferation of knowledge) about available alternative fuels or octane boosters. Two such options are:

1- E85 fuel which is comprised of 85% Ethanol which has an octane rating of about 100 to 105 octane vs the typical 87 to 93 octane pump gasoline.

2- Water / methanol injection systems that can be used either as supplemental fueling system (based on the methanol content which carries an octane rating of 110 octane or higher) or can be used for in cylinder cooling when the water vapor injected with the methanol transforms into steam inside the combustion chamber, thus extracting lots heat out of the combustion chamber, and thus slowing down the speed of travel of the combustion flame front simulating the effects similar to those of a higher octane gasoline.

With the availability of these octane increasing or octane simulating concoctions, it has become more accessible of recent for the performance enthusiast to build a different type of twin charger system that does not require a bypass valve.

In this type of system the supercharger outlet is routed to feed the turbocharger inlet or vice versa. Rather than either the supercharger or the turbocharger feeding the engine individually (in parallel operation) and switching between the two, we are now using a two stage compression system where one stage is the factory supercharger, and the 2nd stage is an aftermarket turbocharger system.

The net result of the two compressors is a compounding of pressure ratios. For example if the turbocharger waste-gate opening spring is set to a setting of 7psi of pressure above atmosphere (which is a pressure ratio of 1.5 given that 1 atmosphere is about 14.7 psig); and if the supercharger is mechanically geared to flow 50% more than the engine (for positive displacement roots style superchargers) at any rpm, thus having an identical 7psi boost setting or a pressure ratio of 1.5; then the resultant pressure ratio of the system combined is :

PR total = PR turbo * PR supercharger = a pressure ratio of 2.25

A pressure ratio of 2.25 is equivalent to 18.4 psi of boost (not 14psi expected by adding the two stages together).

So anyway, how does this relate to octane requirements ?

If the turbocharger is feeding the supercharger for example, and the turbocharger is ingesting fresh air at ambient air temperatures (T1), then:

1- The air exiting the turbocharger will be at a temperature T2, higher than the ambient air temperature (T1) by about 60-80*C depending on the exact turbocharger, and where we are on the turbocharger compressor and efficiency map.

2- The air entering the supercharger will enter at a temperature T2 ~=T1+60 and exit at a temperature T3 which is higher than T2 by about another 60-80*C depending on the exact specifications of the supercharger.

3- If we had an intercooler after the supercharger, then the air entering the intercooler will be at 120 to 160*C above ambient temperatures which is a lot of heat for the intercooler to attempt to shed in the short amount of time that the air passes through the intercooler core.

4- If we have no post supercharger intercooler (which is common on cars where the supercharger is packaged into the intake manifold of the car), then the air entering the engine will be at some 120 to 160*C above ambient.

5- This excessively heated air not only reduces power output (By about 1 horsepower for every 13*C) but it also increases the probability of the air fuel mixture automatically igniting in the motor pre-maturely before the spark plug has fired, and if this pre-mature ignition occurs early enough to catch the piston significantly far away from top dead center, then the battling flame front pushing the piston downwards, and the inertia of the system (and force of other firing cylinders rotating this piston via the crankshaft) pushing the piston upwards will cause extremely high pressures and a temperature rise on the surface of the piston ultimately damaging it and possibly damaging other parts of the motor as well.

For these reasons (pressure compounding, and combined temperature rise) sequential charging has seen very little application in the past. The use of a higher octane fuel by definition means that the air fuel mixture is more resilient to auto-ignition and detonation. Furthermore, in the event of a pre-mature ignition, the higher octane fuel creates a slower traveling flame front which gives the piston more time to travel upwards in the cylinder bore (Closer to top dead center) before meeting the flame front and this reduces the time that the piston surface is improperly pressurized and overheated reducing the possibility of catastrophic failure. Last but not least, the use a water / methanol injection mix includes two phase-change events:

1- The injected methanol changes from a liquid state to a vapor state at its boiling point of 65*C, i.e. as soon as it hits the compressed air mixture coming from the supercharger outlet. This phase change absorbs a lot of the heat out of the air and methanol mixture reducing inlet air temperatures even before the mixture reaches the combustion chamber and starts to get compressed. This temperature reduction goes a long way towards eliminating or highly reducing the possibility of detonation.

2- The injected water, changes from a liquid state to a vapor state at its boiling point of 100*C which depending on the availability of an intercooler in the system, my occur in the intake plumbing before reaching the combustion chamber, or may not occur until the mixture is ignited. Either way, when the temperature is high enough, the water mist injected in the air stream will flash vaporize into steam also absorbing a generous amount of the heat created in the combustion.

The availability of these two octane boosters makes it now possible for aftermarket performance part manufacturers to deliver safe and reliable sequential charging kits to the mass market.

One such kit which I ran across in an article from hot rod magazine was developed by hellion performance (http://www.hellionpowersystems.com) for the factory supercharged GT-500 mustang.

The kit supposedly produce up to 1000 horsepower at a boost level of 24 psi using two 61mm Turbonetics turbochargers.

To achieve 1000 hp requires around 1500 cfm of airflow at 24psi or 1500cfm at a pressure ratio of 2.63, or 750cfm @ 2.63pr per turbocharger.

Since most compressor maps for this size of turbocharger (61mm) peak out at around 600cfm @ 2.63 pr @ around 50% efficiency which is an extreme point on the map (i.e. the turbocharger is maxed out at this point). I’m going to say that I am confident that the kit is capable of supporting 800hp with a typical pair 61mm turbocharger, however 1000hp although dyno-proven, does not agree with what is published on most 61mm turbochargers. I’m not doubting the kit, I am stating that I don’t have a better reference for the specific turbocharger used in the kit.

Furthermore, feeding 1000hp from 8 injectors requires eight 750cc/min injectors by my estimate and this agrees with what is mentioned on Hot Rod magazine’s article of needing 75lbs/hour injectors (each lb/hour is roughly equivalent to 10.5cc/min) at a minimum or a total fuel deliver requirement of 900 liters per hour of fuel at a the fuel rail pressure which is typically around 45psi.

Looking at the flow capacity of the GS342 fuel pump supplied with the kit, which is 255lph @ 30psi, then using 3 fuel pumps gives us the capacity for 765lph which is about 2125 hp worth of fuel, so in that regard the kit is capable of supporting the power figure.

As you can see, it is possible to design such a complex system if the information (Turbocharger compressor map, turbocharger temperature map, supercharger compressor map, supercharger temperature map …etc) information were available before hand. What remains a mystery and an art of trial and failure, is how over-engineered is your engine, how much torque can it produce and still continue to survive, and how long can it continue to survive at elevated power levels. That is altogether a more exciting question to answer.



W.Baker

zee001 asked:


The Chevrolet Corvair engine was a flat-6 (or boxer engine) piston engine used exclusively in the 1960s Chevrolet Corvair automobile. It was a highly unusual engine for General Motors: It was air-cooled, used a flat design, with aluminum heads (incorporating integral intake manifolds) and crankcase, and individual iron cylinder barrels. The heads were modeled after the standard Chevrolet overhead valve design, with large valves operated by rocker arms, actuated by pushrods run off a nine lobe camshaft (exhaust lobes did double duty for two opposing cylinders) running directly on the crankcase bore without an inserted bearing, operating hydraulic valve lifters (which eliminated low temperature valve clatter otherwise seen with that much aluminum in the engine, due to its high degree of thermal expansion).

The flat horizontally opposed (”flat engine”) air-cooled engine design, previously used by Volkswagen and Porsche as well as Lycoming aircraft engines, offered many advantages. Unlike inline or V designs, the horizontally opposed design made the engine inherently mechanically balanced, so that counterweights on the crankshaft were not necessary, reducing the weight greatly. Eliminating a water-cooling system further reduced the weight, and the use of aluminum for the heads and crankcase capitalized on this weight reduction; so that with the use of aluminum for the transaxle case, the entire engine/transaxle assembly weighed under 500 pounds (225 kilograms). In addition, the elimination of water-cooling eliminated several points of maintenance and possible failure, reducing them all to a single point; the fan belt. As with the Volkswagen and Porsche designs, the low weight and compact but wide packaging made the engine ideal for mounting in the rear of the car, eliminating the weight and space of a conventional driveshaft.

Two years after its 1960 debut, the Corvair engine gained another unusual attribute: it was the second production engine ever to be equipped from the factory with a turbocharger, released shortly after the Oldsmobile Jetfire V8.

Aircraft hobbyists and small volume builders, perhaps seeing the Corvair engine’s similarity to Lycoming aircraft engines, very quickly began a cottage industry of modifying Corvair engines for aircraft use, which continues to this day. The Corvair engine also became a favorite for installation into modified Volkswagens and Porsches, as well as dune buggies and homemade sports and race cars.

140

The Corvair’s innovative turbocharged engine; The turbo, located at top right, takes in air through the large air cleaner at top left, passes it through the sidedraft carburetor in between, and feeds pressurized fuel/air mixture into the engine through the chrome T-tube visible spanning the engine from left to right.

The Corvair’s innovative turbocharged engine; The turbo, located at top right, takes in air through the large air cleaner at top left, passes it through the sidedraft carburetor in between, and feeds pressurized fuel/air mixture into the engine through the chrome T-tube visible spanning the engine from left to right.

The initial Corvair engine displaced 140 in³ (2.3 L) and produced 80 hp (60 kW). The high performance optional “Super TurboAir” version, introduced mid 1960 with a special camshaft and revised carburetors and valve springs produced 95 hp (70 kW).

145

In 1961, the engine received its first increases in size via a larger bore. The engine was now 145 in³ and the base engine was said to produce the same 80 hp (60 kW). The new high performance engine was rated at 98 hp (73 kW). In 1962 the high performance engine was rated at 102 hp (76 kW). The high compression 102 HP heads were added to the Monza models equipped with Powerglide when the standard engine was ordered, giving an 84 HP engine rating. 1962 engines returned to automatic chokes after a one year only manual choke on 1961 models.

The ultimate performance was found in the Spyder model, which became available with a turbocharged engine rated at 150 hp (112 kW). The turbocharger was mounted on the right side of the firewall behind the rear seat, fed by both exhaust manifolds; a single sidedraft carburetor mounted on the left side of the firewall fed directly into the turbocharger’s intake, with a chromed pipe leading from the turbocharger’s outlet to what would otherwise be the carburetor mounting pads on the intake manifolds, which were integral parts of the heads. The turbocharged heads received some valve upgrades to improve durability. Exhaust valves on turbocharged engines were made from a non-ferrous material used in jet engine turbine buckets, called ‘Nimonic 80-A’. All other Corvair engines had slight upgrades in valve and valve seat materials as well for 1962.

164

The engine was stroked out (from 2.6″ to 2.94″) displacing 164 in (2.7 L) for 1964. Power output was boosted to 95 hp (70 kW) for the base model and 110 hp (80 kW) in the high performance normally aspirated engine, while the Turbocharged engine remained rated at 150 hp for this year. This increase in stroke was the maximum the engine could tolerate, to the point that the bottoms of the cylinder barrels had to be notched to clear the big end of the connecting rods.

For the 1965 model year, all engines had the head gasket area between the cylinder and the head widened, with a new design folded “Z” section stainless steel head gasket virtually eliminating any risk of head gasket failure. A 140 hp (104 kW) version with 4 single barrel carburetors, and a progressive linkage was introduced in 1965 as option L63 ‘Special High Performance Engine’ and was standard equipment on the Corsa model. The carburetors consisted of a single barrel primary and a single barrel secondary on each head, connected by a progressive linkage; in addition, the heads featured a 9.25:1 compression ratio, and the cars received dual exhaust systems. Engines supplied with the automatic transmission after spring 1965 were modified with a camshaft from the 95 Horsepower base engine, and a special crankshaft gear that retarded its timing 4 degrees- the former to increase torque and smooth idle with the Powerglide transmission, the latter to restore some of the peak HP lost at higher engine speeds by the economy contoured camshaft with short timing.

1966 engines were basically carryover from the 1965 models, however Corvairs sold in California (except Turbocharged models) now featured the General Motors Air Injection Reactor System (AIR), and emissions control system consisting of an engine driven air pump that drew filtered air from the air cleaner, and injected a metered amount into the exhaust manifolds via tubing to promote complete oxidation and combustion of exhaust gasses to lower emissions. Specially calibrated carburetors and slight changes to the ignition timing and advance curves were part of the package. The AIR system had an unfortunate effect of sustantially raising exhaust gas, valve and head temperatures, particularly under heavy loads and this was a drawback on the Corvair where engine cooling could not be easily improved to cope with the higher temperatures. Nonetheless, performance and drivability were not noticably effected in most circumstances. In 1968, all Corvair (and other GM) engines got the AIR system for every market.

The 140 HP engine was officially discontinued for ‘67, but became optional in 1967 as COPO 9551-B, not a regular production option. Chevrolet sold 279 of these engines in the 1967 model year, 232 with manual transmissions, and 47 with Powerglide transmissions. Only six were sold with the four carburetor engine and the AIR injection system required by California emissions standards. These figures include 14 Yenko Stingers and 3 Dana Chevrolet variants of the Stinger.

Both the 140 HP engines and the Turbocharged engines had many special quality features not shared with lesser Corvairs- Moly insert top rings, stellite tips and faces on the valves, a Tufftrided (cold gas hardened) crankshaft, and Delco Moraine ‘400′ aluminum engine bearings- the quality of the 140HP Corvair engine for materials is directly comparable to the Rolls Royce V8 of that era, item for item. It was a fabulous bargain for the $79 premium it commanded over the basic 95HP engine. Performance of the 140HP engine was better than you might expect, with a 5200 rpm peak horsepower output, it offered road performance in a Corvair comparable to contemporary Cadillac models of the day.

The turbocharged engine now developed 180 hp (134 kW). Contemporary reviews describe a similarity in power between the turbocharged and four-carburetor engines throughout the low and mid rpm range, with the turbocharged engine being superior only when it was possible to sustain boost continously. The turbocharged engines long suit was highway acceleration, flooring the accelerator at turnpike speeds produced ferocious acceleration in the upper speed ranges as the turbocharger began to boost, reaching manifold pressures approaching 15 PSI. No wastegate was used on the Corvair turbocharged engine, boost was controlled by careful balancing of exhaust restriction, mostly via the muffler, and intake restrictions from the smallish Carter YH carburetor used. Preignition and knock under boost was controlled using a novel ‘pressure retard’ device, essentially a modified vacuum advance device, on the specially curved distributor, as boost pressures built, ignition advance was progressively reduced to preclude detonation.

BoostTown.com asked:


This a article from BoostTown.com

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Visit us to find more articles will color pictures that aid in the clarification of the various automotive components

For the full article go here:

http://www.boosttown.com/forced_induction/turbo.php

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The turbo (also known as turbocharger) has been around for many years, almost as long as the internal combustion engine itself. A turbocharger, has two wheels on it. One is called the turbine and this sits in the exhaust system. The exhaust gas leaving the engine causes the turbine and the shaft fixed to it, to spin.

On the other hand of the shaft is the impellor, or compressor wheel. This pulls air in and the forces into the engine. For this to work effectively, the impellor wheel typically spins at 120,000 – 150,000 RPM (Revolutions Per Minute).

Many kinds of bearings used at these high rotational speeds need lubrication and cooling systems. The turbocharger’s lubrication system can be an isolated system or receive oil from the engine’s oil supply. For cooling the lubrication system may double as the cooling system, separate coolant may be pumped through the center housing from an outside source such as the engine coolant system, or the turbine may be air cooled. An oil lubrication and water cooling system using engine oil and engine coolant are commonplace in automotive applications. Special kinds of bearings, e.g. foil bearings, can reduce or eliminate the need for lubrication and reduce the cooling requirement.

Turbos rely on the flow of the exhaust gas through the turbine housing, they only start to spin after ignition has taken place and so there is a delay between opening the throttle and the turbo spinning and producing boost. This is known as ‘turbo lag’ and is considered to be a downside compared to superchargers.

The turbine and impeller are each contained within their own housing on opposite sides. These housings collect and direct the gas flow. The size and shape can dictate some performance characteristics of the overall turbocharger. The area of the cone to radius from center hub is expressed as a ratio (AR, A/R, or A:R). Often the same basic turbocharger assembly will be available from the manufacturer with multiple AR choices for the turbine housing and sometimes the compressor cover as well. This allows the designer of the engine system to tailor the compromises between performance, response, and efficiency to application or preference.

John Hartley asked:


DIESELS are still gaining popularity in Europe, thanks to low gas mileage and good performance. The latest diesel cars can take on gasoline engined cars and come out on top!

All turbocharged diesels generate much more torque than gasoline engines, so you get better mid-range acceleration. In other words, from, say, 40-80 mph, a good diesel will see off a good gasoline engine car of the same apparent performance.

Jaguar has introduced a special version of a V-6 2.7 liter diesel that has been developed in Europe jointly by Ford and Peugeot. This is the most advanced diesel around at present, with the brand-new piezo-electric injector operation, the latest common rail injection system and twin turbochargers.

PIEZO-ELECTRIC INJECTORS

What are piezo-electric injectors? Cunning little ceramic devices, and when an electric current is applied they produce a pressure, and so can be used to force fuel into the cylinders. The thing is that they can be operated four times faster than other electro-mechanical injectors so the injector can be opened and closed incredibly quickly. Also, the amount of movement is very small, and you get less noise that you get from mechanical injectors.

Like I said, very cunning, and they all go with high pressure injection to give high power, low noise, emissions and gas mileage. It’s developments like these that mean we’ll have some diesels in Fast-Autos soon – but not a lot!

As a result, the fuel is injected at horrendously high pressures with incredible accuracy. The result? Masses of power, and almost no smoke, the weakness of old-fashioned oil burners, like the dreadful engines GM introduced about 20 years ago.

This new Jaguar S-Type diesel, develops 206 bhp so it lives up to the Jaguar tradition of high performance. Maximum torque is 320 lb ft (430 Nm) which is more than the 4.2 liter gasoline engine can manage without a turbocharger. Although performance is not sensational, it is definitely not what you’d expect from a diesel.

The Jag diesel will push the S-Type automatic up to 60 mph in about 8 seconds, and top speed is 140 mph. You’ll get the idea that Jag regards this as a sporty engine from the fact that it has a six-speed manual or automatic box – both are supplied by ZF. Of course, the most powerful S-Type is the S-Type R.

BMW HAS AN EVEN MORE POWERFUL DIESEL

BMW is also ready with a very powerful 3.0 liter diesel engine which turns out 272 bhp, which would be considered very nice thank you from most makers of 3.0 liter gasoline engines – Ford’s top version of its nice 3.0 liter V-6 develops 225 bhp. BMW uses twin-stage turbocharging to get this much power. In this system, one small turbocharger provides power at low speeds, and a bigger turbo is matched to high speed requirement. It is switched in when the speed and load increase sufficiently, and so can generate as much power as a gasoline engine of the same size.

If that is not enough power consider the latest news. Audi is racing diesel-powered cars at the Le Mans 24-hour race! These V-12 engines develop more than 600 bhp, and will challenge the best gasoline engined sports-racing cars.



Carr

Redline Motive asked:


Why has supercharging become so popular?

There are a number of reasons. First, an efficient supercharger system can produce yesterday’s musclecar performance using today’s low-octane gasoline, with exceptional reliability and minimal impact upon fuel economy. Second, superchargers have developed to the point that they are easy to install and simple to maintain, especially when compared to pulling, rebuilding and fine-tuning an engine. Finally, unlike nitrous oxide, which requires frequent repurchase of fuel, once a supercharger is installed there is no more expense or hassle associated with performance. In short, supercharging delivers exceptional performance with little of the hassles traditionally associated with high performance. Centrifugal supercharging is the only way to make a reliable 500, 600, 700+ horsepower on otherwise stock, daily driven V-8’s.

How does supercharging increase engine performance?

Superchargers achieve performance gains by increasing the density of the air/fuel charge within the combustion chambers of an engine. This increase in density is achieved by forcing additional amounts of air (beyond the amount of air that normal atmospheric pressure would force into the engine) at the lowest temperature possible. CFM measures the volume of air that an engine is flowing, while MAF (mass air flow) also factors in the temperature of the air charge, since a cooler charge is more dense and therefore more powerful. So in more technical terms, supercharging increases both the volumetric efficiency of the engine and the mass air flow through the engine to produce gains in both horsepower and torque.

How much horsepower will a supercharger add to my engine?

Although some manufacturers claim a specific horsepower increase, superchargers actually add horsepower as a percentage gain (percentage of an atmosphere). Assuming an engine with a compression ratio of around 9:1 running pump gas,if a supercharger gives your engine 14.7 psi of boost (another atmosphere) that will essentially double the output of your engine, everything else being equal. After adjusting for thermal and mechanical energy transfer, if an efficient centrifugal supercharger is generating 7.5 psi (approx. 1/2 an atmosphere), you will see around a 35-40% gain in horsepower and torque at your non-supercharged maximum horsepower rpm. If detonation forces you to use an ignition/timing retard system, you will of course see less of a gain because backing off several degrees of timing will greatly reduce an engine’s power output. At higher boost levels, the heat generated by compressing air will produce diminishing returns as the boost is increased, although the use of intercooling or racing fuel can avoid this scenario of diminishing returns. Assuming the use of intercooling to run higher boost levels while maintaining reliability, a 100% increase can generally be achieved at around 17 psi on an engine with 9:1 compression running pump gas.

What type of fuel do I need with a supercharged automotive or truck engine?

The primary issues that determine the type of fuel needed are whether the engine is fuel-injected or carbureted, the compression ratio of the engine, and whether or not the supercharger system is intercooled.

For Intercooled ProCharger EFI/TPI applications with compression ratios less than 9.5:1, boost levels of 14-17 psi can be safely run with full timing on pump gas, and will produce horsepower gains of 75-100% (depending upon the boost level and the motor specifications). For 9.5:1 EFI/TPI applications running without an intercooler, boost levels above 5 psi will require the use of ignition/timing retard on pump gas, and will produce horsepower gains of 35-45%. Boost levels above 12 psi should generally be avoided even with racing fuel on a 9.5:1 motor. Of course, lower compression motors will be able to run more boost, and higher compression motors should run less boost, everything else being equal.

For carbureted motors, the rules are slightly different. Carburetors deliver the vast majority of fuel in a liquid state, and as this raw fuel atomizes from liquid to gas, a chemical state change actually occurs. Due to this endothermic reaction, which draws heat and cools the incoming air, a carbureted motor can safely handle more boost than a comparable EFI/TPI motor. For carbureted engines with compression ratios of 9:1 or less and boost levels in the 8-14 psi range, pump gasoline works very well. Compression ratios of 10:1 and higher require lower boost levels, higher octane fuel, intercooling, or some combination of the above. Compression ratios in the 7or 8:1 range can usually handle 12-20 psi on pump gasoline.

What is detonation, and how can it be controlled?

Detonation, or engine knock, occurs simply when fuel pre-ignites before the piston reaches scheduled spark ignition. This means that a powerful explosion is trying to expand a cylinder chamber that is shrinking in size, attempting to reverse the direction of the piston and the engine. When detonation occurs, the internal pneumatic forces can actually exceed 10x the normal forces acting upon a properly operating high performance engine. Detonation is generally caused by excessive heat, excessive cylinder pressure, improper ignition timing, inadequate fuel octane or a combination of these. Of the previous, excessive heat is usually the culprit. As an engine is modified to generate more power, additional heat is produced. Today’s pump gas will only tolerate a finite amount of heat before it pre-ignites and causes detonation. Although forced induction engines usually produce far less heat than comparable naturally aspirated high compression engines, the cylinder temperatures in intercooled engines are radically cooler yet. It is rarely boost that causes detonation, just unnecessary heat. An intercooler is such a natural solution for forced induction, that in almost every sophisticated application, intercooling is part of the package.

For engines that are experiencing detonation problems, the primary options are the use of ignition/timing retard systems, higher octane fuel, or intercooling. While ignition retard systems can be helpful in certain situations, they can also greatly reduce the horsepower output of an engine, as any reduction in timing will reduce horsepower. And while a reduction in timing can save a motor from detonation, the excessive heat which was causing the detonation is still present. Intercooling, on the other hand, actually removes the heat which causes detonation, and allows higher boost levels to be safely run with full timing on pump gas. This produces the maximum benefit in terms of both horsepower gains and engine protection, without any additional maintenance or hassle.

How will a supercharger affect my fuel economy?

Although roots superchargers have significant parasitic load and do dramatically decrease fuel economy, centrifugal superchargers will yield approximately the same fuel economy as normally aspirated engines, under normal throttle conditions. When racing, however, fuel enconomy will decrease given the supercharged engine’s ability to consume additional fuel and produce additional horsepower.

Will a supercharger shorten the life of my engine or drivetrain?

That is a very subjective question, as the manner in which an automobile is driven directly affects engine life. Assuming a properly tuned system, proper oil change and engine maintenance, and similar driving, supercharging generally will not shorten the life of an engine, just as is the case with OEM turbocharging (with proper cooldown for turbochargers. A cooldown period after driving is not necessary with supercharging). This is especially true of centrifugal supercharging, which generates boost in line with engine rpm, unlike roots and twin ***** blowers, whose low rpm boost can place additional strain on the engine and drive train.

Superchargers can be used with automatic or manual transmissions and will not increase transmission wear under normal driving. When racing, however, the additional torque provided by supercharging will place additional load on the transmission, especially when increased traction is present, such as with slicks. This impact is minimized when the boost increases with engine rpm, as is the case with centrifugal supercharging and turbocharging.

What is the difference between Supercharging and Turbocharging?

A supercharger is a mechanically driven air pump that is connected directly to the engine crankshaft via the serpentine belt. A turbocharger is driven by the flow of exhaust gas which is generated as part of the engine combustion cycle.

Why choose Supercharging over Turbocharging?

Because turbochargers depend on the energy in the exhaust gas stream to spool up and generate boost pressure, there is often a delay in the response of the engine at lower engine speeds where exhaust energy is lower. This delay is often referred to as “Turbo Lag”. On the other hand, a supercharger is directly driven by the crankshaft of the engine, and there is no delay in engine response at lower engine speeds. This allows supercharged engines to have instant throttle response and better vehicle driveability.

If more air is pumped into the engine, then more fuel must be used also…Doesn’t this mean less fuel economy?

If a supercharged 3.8L V6 is compared to a naturally aspirated 3.8L V6, the supercharged V6 does use slightly more fuel. However, the power and performance of the supercharged V6 is comparable to a larger V8 which uses much more fuel to achieve the same performance.

Does the Supercharger provide boost at all times?

No. Under cruising conditions, the compressed air from the supercharger is bypassed, and is recirculated in the supercharger, improving fuel efficiency. Under acceleration, the bypass is closed, and the “boosted” air is sent into the engine to provide increased response and power.

How reliable are supercharged engines?

General Motors has been offering a supercharged version of the 3800 V6 engine since 1991. The Supercharged 3800 Series II engine has one of the best warranty ratings amongst all of General Motors powertrain offerings. Along with GM, other automakers like Jaguar, Mercedes-Benz, Nissan, BMW-Mini, and Ford all have used superchargers as an effective and reliable alternative to larger, less fuel efficient powertrains on various cars and trucks.



George

Evander Klum asked:


A car is an investment. Whatever your reason is for buying one, it is important that you get the car that suits you. Some would buy just for the sake of having one. Then suddenly you will realize you actually did not have the right one for you.

It is prudent to compare vehicles when planning what to buy. By doing this, you will know which is good, better, best, bad, worse or worst.

There are certain things to consider when comparing vehicles. One is the cargo volume or the so called luggage capacity. It is referred to as the volume in the trunk/area behind the seats. So when talking about maximum cargo volume, this refers to the volume when the rear seats are bent over, and when the storage bins are full in capacity. The cargo volume is moderately important to buyers since some would probably be filling their vehicles with pieces of luggage, bags of grocery items and other cargo every now and then.

As a car buyer, you need to know about power-to-weight ratio. From the term itself, it suggests some mathematical equations, but not really as difficult as those during your school years. The ration is derived from a vehicle’s horsepower as related to its weight. Power-to-weight ratio is congenial when there is greater horsepower and lower weight. While looking for the right vehicle, keep in mind that the horsepower figure is just a part of the performance equation. If you are concerned with the performance of your car when accelerating, better consider the car’s power-to-weight ratio.

You definitely would want safety in you car, right? Electronic stability control or traction control spells it all. This system is composed of radars and detectors that inform the driver when a future crash can happen; the brake system is not functioning well; when the wheels are not properly align; and so on.

Nowadays, there are several vehicles in the market that have this electronic stability control/traction control. This is to ensure further comfort, excellent driving and safety while on the road.

The resale value should also be considered in comparing cars. This is referred to as your vehicle’s future value. This can be affected by several things such as the amount of mileage you have put on it or the number of times it experienced accidents.

The resale value is one of the factors because it is important that you pay the right amount for your car. If it had been in several accidents, it implies less cost. If it had never been in an accident, it might definitely cost high because its value is not yet much deteriorated.

For practical buyers, this is the most important thing to consider.

Another thing to keep in mind when comparing is the car’s turbocharger. It is a supercharger unit that is powered by an exhaust-fed turbine under acceleration. The turbine commands a pump to give more air into the cylinders when called upon. In effect, a better pick up is experienced. Turbo, which are manufactured during the “not so high technology era”, were infamous for fall between the time the accelerator was pressed and the time the boost was felt. Furthermore, the boost would spike suddenly without a straight response. On the other hand, turbo that are manufactured in the “very high technology era” generally perform better in both aspects.

A car expert knows that greater air supply through the engine is a must. In this matter, a supercharger gives a big help. Commonly called as “blower”, a supercharger is a compressor that pushes more air into the car’s engine than it would ordinarily capture. Generally speaking, this term technically applies to all types of compressors even turbochargers. However, it is also commonly referred to the mechanically driven units. And since they are always functioning, the turbo do not experience lags and peaks. And this is good news, right? So better compare analytically the vehicles’ supercharger.

Another thing to consider is the curb weight. It is the most appropriate way of measuring a vehicle’s weight. This is referred to as a car’s drag with all its standard equipment and fluids onboard such as gas, oil, coolant, etc., which cumulatively account for more pounds than what you usually know.

Finally, but certainly not the least priority in comparing cars, the vehicle identification number (VIN). It is a code of letters and numbers reveals the manufacturer and where it was made and when. It further goes along with other miscellaneous details. This is more important in used vehicles in order to investigate its reported history.

If you are looking for a BMW car, every single detail is written in the BMW manual.



Bob

Mike Willis asked:


Welcome back to part two of my article series. This mini-used car buying guide is a compilation list of my most important questions to ask when buying a used car.

To recap from part one, over the phone we want to make clever inquiry to see if we can establish with some certainty that the seller is not a private car dealer. Then we ask them questions to determine whether how long they have owned the car and if they are the original owner. The final area covered in part 1 was to pay close attention to the sense we get from the seller’s response to our asking about their reasons for selling. If we are satisfied with the outcome of this initial round, it is time to get a bit more specific.

One of my top questions to ask about buying a used car is whether it has a gas or diesel engine. This may not be applicable unless you are looking for a diesel, as the vast majority of cars only come with a gas motor. However, if you are looking for incredible economy and bulletproof reliability, you will want to consider buying a car equipped with a diesel or even better, a turbo diesel engine. VW Jettas and Golfs are and were and still are built with both gas and diesel motors, and those motors last a long, long time!

Ask them how many kilometers or miles are on the car? For a gas engine, anything much over 250,000 km or 150,000 miles is a bit too much, unless the car has been meticulously maintained. In the case of a diesel engine, 300,000 km or 180,000 miles is just getting going. If it has been meticulously maintained, a diesel can go for a million kilometers.

Determine whether your potential future companion has a standard or automatic transmission? Which would you like better? Generally, a standard 5 speed transmission is the best choice, as it is less complex and more fuel efficient. C’mon! Stick is more fun anyway!

Find out it they have service records. If they have no service records, it is a strong indication that the car has not been well maintained. By looking at the service records, you can see the maintenance history, and any repairs. For example, a receipt for a new engine adds value to any car. When the time comes to sell your car, this can be handy evidence to present someone to backup your request for top dollar.

No list of tips on buying a second hand car can be complete if it doesn’t include being sure that you ask the seller if it has ever been in an accident. If their answer is yes, ask them if it was a write off. If yes, move on. There are lots of other cars to choose from. If their answer is no, find out how long ago the accident was, and what area of the car sustained damage? You will want to look carefully at these areas when you go to see the car.

If the damage is recent, it may be difficult to tell how well the repairs will hold up. If it was a long time ago and it still looks okay, that can be a good sign. If the doors were affected, there is a good chance that they don’t close perfectly anymore, and may make whistling sounds at highway speed. Very annoying on long journeys!

Okay, we are getting some good information from our seller! That’s it for part 2. Stay tuned for part 3 where I will dive into the nitty-gritty of how to narrow down your search for the perfect used car.



Fowler