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Function of a turbocharger

A turbocharger is for achieving high torques and therefore higher motor performance. This is doable by compressing the induction air. Because of the increased density of the oxygen, more oxygen can get into the internal engine. With the increased oxygen supply a better combustion is possible - the motor performance goes up. The heat and motion energy of the exhaust fumes are used to power the exhaust-gas turbine of the turbocharger. The exhaust-gas turbine drives the compressor. The compressor compresses the induction air which causes a warming up of the compressed air. In the air-cooler the hot compressed air is cooled down.

Problem areas of the turbocharger:In the upper motor speed range a higher speed range of the exhaust-gas turbine is reached which causes a higher compression of the induction air as necessary. In the lower motor speed range the exhaust-gas turbine is not reaching the required speed range. This is causing that the induction air is not enough compressed. Therefor the motor is not reaching the wanted performance (turbogap).

Function of a turbocharger

A turbocharger is for achieving high torques and therefore higher motor performance. This is doable by compressing the induction air. Because of the increased density of the oxygen, more oxygen can get into the internal engine. With the increased oxygen supply a better combustion is possible - the motor performance goes up. The heat and motion energy of the exhaust fumes are used to power the exhaust-gas turbine of the turbocharger. The exhaust-gas turbine drives the compressor. The compressor compresses the induction air which causes a warming up of the compressed air. In the air-cooler the hot compressed air is cooled down.

Problem areas of the turbocharger:In the upper motor speed range a higher speed range of the exhaust-gas turbine is reached which causes a higher compression of the induction air as necessary. In the lower motor speed range the exhaust-gas turbine is not reaching the required speed range. This is causing that the induction air is not enough compressed. Therefor the motor is not reaching the wanted performance (turbogap).

There are several factors to take into account when turbocharging a vehicle. First, if the engine has high mileage and/or a good deal of wear, your money may be better spent freshening up the rings, bearings, valve guides, etc. before you invest in a turbo system. The additional stress put on the engine’s internal components by the increase in horsepower may cause a weak engine to expire!Furthermore, you -should determine whether, the engine’s compression ratio permits the addition of a turbo. Since we’re already compressing the charge air with the turbo, the higher the engine’s static compression ratio is, the greater the tendency toward detonation. In other words, the higher your compression, the less boost you can run.

You must also take the fuel and ignition systems into account. I your fuel injection or carburetor going to be able to compensate for the additional airflow generated I the turbocharger and add a corre sponding amount of fuel under boost? Is your ignition system cap able of retarding the spark timing under boost, if necessary? Both fuel and ignition systems must be up the engine’s demands, as the incorrect fuel delivery or spark timing can cause harmful detonation( Of course, correct fuel delivery and spark timing can make a great deal of horsepower!)

Conclusion
In our opinion, when properly installed a turbocharger system is capable of producing the best bang for the buck. When factoring in its reasonable cost, relatively compact size and adaptability to any sport compact car, turbocharging makes a whole lot of sense for the
enthusiast seeking big time horsepower gains!

For those that can’t get enough of turbo-related goodies, check out the Turbo Club Of America. A one-year membership entitles you to club discounts on performance equipment from participating manufacturers and six issues of Turbo Club News plus much more!

Author Chris Weisberg is a Turbocharger Specialist for Turbonetics, Inc., manufacturers of custom turbochargers and controls.

A turbocharger is an exhaust-driven turbine that boosts an engine’s power output.Normally, the downward motion of the pistons pulls air into the engine; this air is mixed with fuel, which is ignited to make power. Stepping on the accelerator increases the amount of air that can be drawn in. (So you’re not really stepping on the gas; you’re stepping on the air!)A is a pair of turbines (a type of fan blade) on a common shaft. One turbine is piped to the exhaust, the other is piped to the intake. The flow of exhaust spins the exhaust turbine, which also spins the intake turbine. The intake turbine blows air into the engine at a greater rate than it can pull in. The greater volume of air can be mixed with a greater volume of fuel, increasing power output.In order for the turbocharger to work, there needs to be enough exhaust pressure to spin (”spool up”) the turbines, so they don’t really start to boost power until the engine is spinning at 2000-3000 revolutions per minute (RPM). This is called turbo lag. Once the turbo spools up, look out — the result is usually a strong surge of power, accompmanied by a jet-engine-like whistle.

Turbos are a lot of fun and well suited to sporty cars, but their wind-up-and-go power delivery can make for a neck-snapping ride. That’s why family and luxury cars generally use larger engines to develop more power, instead of a turbocharger.

There are a variety of kinds of boost controls on the market. Some control air flow in and out of the compressor (such as pop-off valves or restrictors), but the most efficient (and for this reason the most popular) are controllers that work on the turbine side, which are known as wastegates.

As mentioned earlier in the article, the turbine wheel is driven by exhaust gases. A wastegate functions by taking a portion of the exhaust gas that would drive the turbine wheel and rerouting to bypass the turbine wheel. This way we can control the speed of the turbocharger and therefore, limit the boost the turbo produces. A boost control should be used so that you can limit the total amount of boost to the engine to prevent detonation.

There are other details to contend with, such as fuel enrichments, ignition controls, where and why to install check valves in vacuum lines, and so on. Therefore, it will be very helpful to both you and those helping you if you do your homework ahead of time. There are several useful books written specifically on the subject of turbocharging, some of which are available from bookstores

The fundamentals are basically these:

* Exhaust must be routed to the turbine inlet of the turbocharger. This is typically done with a turbo exhaust manifold, when available, or a custom adapter plate to allow you to mount the turbo to the factory exhaust manifold.

* Exhaust must be directed out of the turbine discharge of the turbocharger. This can typically
be done at a muffler shop, where a custom down-pipe will be fabricated, to connect the turbine
discharge side of the turbo to the exhaust system.

* Air must be ducted from the air filter to the compressor inlet, and from the compressor
discharge to the intake manifold. This is typically done in aluminum or steel tubing which is then coupled at all joints by silicone hose couplings or nitrile rubber connectors. Flex hose is sometimes used on the inlet side of the compressor since it is only subjected to vacuum, not pressure.

* Pressurized oil must be fed to the turbocharger’s bearings. The most common place to tap into an oil galley is at the oil pressure sending unit.

* An oil drain line must be installed so that the oil used to lubricate the turbocharger can drain back to the oil pan. This is typically done by brazing a hose fitting to the pan and using a large diameter, oil-resistant hose from the bottom of the turbo to the side of the pan. The heart of the turbo system is of course, the turbocharger itself. The size and model of turbo that you require can vary radically depending on your application (i.e. street, track, drag). The larger turbochargers can produce tremendous amounts of power, but they will take longer to spool up (turbo lag). This is a function of the size of compressor and turbine wheels, as well as the turbine housing itself. A turbocharger applications specialist will be able to assist you in
choosing the proper turbocharger for your car.

Many people are confused about the differences between a super charger and turbocharger. Booth families of devices are basically air compressors, but they’re operated’ quite differently from each other. A supercharger is mechanically driven by the engine itself; usually off the crankshaft by a cogged belt and pulley system. This means that a supercharger uses up some of the engine’s horsepower just to drive itself - often 60 horsepower or more! Fortunately, the airflow generated by the supercharger helps it produce far more horsepower than it requires to operate.

A turbocharger, however, is driven by the thermal energy of the exhaust gases of the engine. With non-turbocharged vehicles, these gases are simply discharged out of the engine as quickly and efficiently as possible, wasting a surprising amount of energy in the form of noise and heat. A turbocharger uses some of that energy (which would otherwise be wasted) to drive its compressor, without the attendant horsepower loss of a crankdriven system.

The result? The turbocharged engine stands to produce more peak horsepower than a comparable supercharged engine, mostly because the turbo does not require any power from the crankshaft. Also, the turbocharged engine will typically run much quieter than a supercharged engine since the turbo has no gears, belts or pulleys and because the turbo itself muffles the exhaust. And while many superchargers are large, heavy devices (we’ve all seen Roots-type blowers sticking up through the hoods of muscle cars), the turbocharger is a relatively small package - a turbo capable of producing 600 horsepower can weigh only 15 pounds and be easily held in one hand. It is for these reasons that turbocharging has become increasingly popular with both OE and aftermarket manufacturers. Automakers can produce lightweight vehicles with good fuel economy yet excellent power thanks to the turbo. The aftermarket manufacturers have jumped into the game, offering larger turbocharger “upgrades” in place of factory turbos, or even complete turbo “kits” to convert a naturally-aspirated vehicle to turbocharged configuration. One question we hear quite often at SCC is whether a normally-aspirated engine can be turbocharged. Any engine can be turbocharged, and there are a number of turbo kits available to allow you to do this to a variety of vehicles. However, if you cannot locate a kit for your vehicle (or you choose not to purchase an existing kit), you can build a custom installation yourself.

The term “turbo” or “turbocharger” is frequently heard in the world of high-performance. However, many people are unfamiliar with these devices and this is unfortunate, because turbocharging is one of the most cost-effective methods of producing maximum horsepower per dollar.

The turbo itself is a relatively simple device. Its moving parts basically consist of two wheels mounted on a common shaft; the turbine wheel and compressor wheel. The shaft is mounted in oil-fed bearings inside a compact center housing and the wheels are located at either end of the shaft, each one in its own housing. In function, exhaust gases leaving the engine are directed into the turbine housing. This housing directs. the high-velocity gases at the turbine wheel, causing the wheel to rotate. After the gases have passed through the turbine wheel, they exit the turbine housing and are discharged through the vehicle’s exhaust system. The rotation of the turbine wheel drives the compressor wheel (which is at the opposite end of the shaft). As the compressor wheel spins, it inducts air into the compressor housing. There it is compressed and discharged into the intake system of the engine, providing boost pressure.  

A turbocharger creates horsepower by forcing more air into an engine than that engine could normally ingest during the intake portion of its cycle. It does this by compressing air then forcing it into the intake manifold and ports. This additional pressure is known as boost pressure. Boost pressure is typically expressed in pounds per square inch or millimeters of Mercury. This gives us an indication of how much additional airflow and pressure there is available to the engine when the turbo is operating. The amount of boost pressure is usually determined by a wastegate. This device is frequently an integral part of the turbine housing. It functions by passing exhaust gases around the turbine wheel so that the amount of exhaust driving the turbine is limited. In this way, by opening the wastegate at a preset boost level, we can control the speed of the turbine wheel (which is driving the compressor) to maintain that boost pressure without overboosting or providing the engine with too much airflow and pressure.

Small-Frame Performance Turbochargers: In this section we have added to our existing lineup additional performance related GT15 and TBO25 assemblies. New to this family are a variety of intermediate size TBO2/22 turbocharger assembly models. For those special projects requiring instant boost the popular VNT15/22 are now in stock and ready for order.

Mid-Frame Performance Turbochargers: An addition to the mid-frame family is the new TBO28 ceramic turbine wheel turbocharger. In addition, the TA34/TB34 have been grouped together with new assembly configuration offerings. New large trim TBO3 turbocharger outline assemblies have also been added for more product line diversity.

Standard-Frame Performance Turbochargers: Among the popular TO4B and TO4E families are many new turbocharger outline assemblies which have been added to this product line. A wide variety of compressor and turbine stage offerings will allow more selections for your precise engine matching capability.

Large-Frame Performance Turbochargers: This is a new family which is being introduced in this Phase II launch. As we grow into larger frame assemblies we will begin with the launch of TA45 based turbocharger assemblies. Unique to these assemblies are the standard TO4 based turbine housing flange mounting feature. This is unique since majority of aftermarket kits are designed around the standard TO4 flange mounting pattern. Now you can adapt a Large-Frame large bearing T45 based performance turbochargers directly to your existing manifold without any mounting modifications. In the future we plan to grow this Large-Frame Performance Turbochargers family with various hybrids to meet the 999+ horse power single turbo application requirements.

GT Series Ball Bearing Performance Turbochargers: The GT Series Ball Bearing Turbocharger is one of AlliedSiginal’s latest development in performance turbocharger technology. The Garrett “full cartridge” dual ball bearing systems have been qualified in various OEM production based programs. The same ball bearing system’s durability and reliability has been well proven in winning Indy 500 race cars and in grueling 24 hour endurance races. Presently the GT Series are available to the aftermarket in limited Pre-Production GT25 GT30, GT35 and GT42 designs.

Now available GT24/45 800 HP turbocharger Copyright © 2000 Ray Hall Turbocharging.