Compound turbo sizing gas engine

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Compound turbo sizing gas engine

Department of Transpertation. So you have decided to turbocharge your car or upgrade your existing turbo, but are stuck on what size of turbo would be right for you. It would be nice if turbocharging was like many other decisions where bigger is better, but not so. We go to the dyno and continue turning up the boost pressure till we hit our HP goal.

We eventually do meet our goal of whp but we had to run such high boost pressure to reach that goal, that race gas was required.

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A bonus though of running such high boost and hitting high boost low in the RPM band was we made tons of torque too. We made HP and Torque. How exciting, but then our engine builder told us that making that much torque will most likely bend our stock rods and beat on our bearings a lot more.

To fix this we need to be grabbing for our wallet once again and have the motor fully built with forged parts. Well the owner empties his wallet and hits the street. Also they think to themselves that if they wanted to wait till RPM to get into the go peddle they would have just bought a larger turbo.

With the same goal of whp the owner hits the dyno and is able to make whp on pump gas do to the fact that not much boost pressure is required to get the large compressor and turbine wheel to flow enough air to make HP. The owner is excited that he can make this power with cheap pump gas and enjoy that power daily.

With this news the owner celebrates and leaves his wallet in his back pocket. Next the car takes to the street. In 1st gear the turbo is lazy so not much boost pressure is made, but the car is still very quick since traction is maintained and a 3. The owner shifts to 3rd and traction is all there and so is the turbo.

Turbo 4 Rotor RX-7 SCREAMS on the Dyno - Mazzei Formula

What is nice is the larger turbo pulls hard all the way to redline. So which set-up is better? Well if money was infinite and traction was infinite than the smallest turbo to reach your HP goal wins hands down.

Better response, more torque, and with infinite traction it would put car lengths on the larger turbo car till the larger turbo cars boost came in, and also would be much more responsive and fun to drive. BUT, in the real world where money matters, and traction is a big problem, which one is better?? So, this is some food for thought to those that say to buy the smallest turbo that satisfies your HP goals.

An owner should think about a lot more than just reaching their HP goal.Modifications such as programmers, air intakes and exhaust systems were added initially, with great end results. After the entry-level add-ons showed little to no detrimental side effects, many decided to push the envelope further, turning to larger injectors and aftermarket lift pumps for even more gains.

Eventually, the time came when all of the added fueling needed to be paired with more airflow. With the stock turbocharger pushed to its max, aftermarket turbo setups became the next logical upgrade. Today, compound turbo arrangements are almost as common as injector upgrades when it comes to diesel powered pickups. From hot-running street trucks to competitive sled pullers, they can be found everywhere.

Even truck owners that work their rigs for a living are adding a second charger under the hood. The primary benefits of compound systems are great low-end torque, strong mid-range and exceptional top-end performance. This is because a small high-pressure turbo is utilized to get things started at lower rpm, while a larger atmosphere, or low-pressure unit takes over at higher rpm. Available sizes either from factory or aftermarket suppliers typically range from 75 mm labeled an S to 88 mm labeled an S compressor wheels, along with 83 mm to 96 mm turbine wheels being the norm.

These turbos feature a T6 mounting flange, have no problem handling 60 psi of boost or moreand can be had with a degree thrust bearing assembly for added reliability. They offer arguably the best bang for the buck in the diesel industry, with affordability, durability and big performance gains being their key strong suits. For budget-minded truck owners, add-a-turbo kits are frequently employed.

Turbo-compound engine

These types of systems are good for the hp to hp. Find out how to make your Duramax diesel engine invincible. One of the most prevalent compound turbo setups in the diesel industry bundles an S BorgWarner based S unit on top of the aforementioned S, which acts as the atmospheric turbo on 5. While smaller in size, they are quick-spooling, great for towing, support hp and can be had on a reasonable budget.

The most budget-friendly Cummins engine is the 3. Here's what you need to know about this 4BT. Even though the larger displacement of the 6. An age-old combo for making big horsepower with the 5. Here is an example of a compound arrangement intended for work.Try it free for 14 days. View Full Image. Diesel Power Magazine how to. One of the more difficult technical aspects of diesel performance is choosing a turbocharger. If you put enough fuel through a diesel engine, it's going to run up against a point where the stock turbocharger becomes very inefficient.

The stock turbo can even overspeed and the compressor wheel can explode, sending metal into your intercooler and engine. Also, having a turbocharger that is mismatched to your engine can cost you horsepower, and we all like horsepower. So what's the right turbo to choose? Well it depends on many different factors. For racing engines the answer is simple: as big a turbo as you can spool, or that the rules will allow.

For a street truck, it is a little more complicated. Drivability has to be a concern. It's no good to sit there waiting for your turbocharger to spool while your buddy passes you, so on a street truck it's better to be a little smaller than too large. Taking Stock First off, you have to decide if you need a new turbocharger. Cummins and Power Stroke engines can support to hp to the wheels with a stock turbocharger.


Duramax engines can hit a hot and smoky hp on a big tune with a stock turbo. So if you're an intake and exhaust type of guy, you probably don't need a new turbocharger. If you're shooting for to hp or if you towthen it's time to start shopping. In the case of an overfueled stock engine lots of black smokebuying a new turbocharger will add horsepower, lower exhaust gas temperatures, and be capable of supplying higher boost pressures without risk of failure.

Weights And Measures When we're talking turbocharger sizes, the most commonly referred to measurements are the compressor wheel's inducer diameter, turbine wheel diameter, and turbine-side housing ratio. All of these numbers affect how the turbo will behave.I just finished rebuilding my Detroit Diesel 6V53T military engine. In the process of rebuilding, I changed some parts to turn the engine into a truck engine. Unfortunately that process made mounting my turbocharger impossible with stock parts.

Since I have to go through all of that trouble, I was thinking of running a compound turbocharger setup to increase low end torque, and create more boost at lower rpm's. Because the turbocharger wheels are so big, I would expect that it doesnt make any boost until the engine is revved up considerably.

This engine will be used in a truck one day, so it will be optimal to have some boost at lower rpm's. How do I figure out what turbocharger I need to buy in order to get maximum efficiency out of the engine?

Mine doesnt have an aftercooler, otherwise, its the same engine. Both are rated with N70 injectors. I think that my best choice for now is to still find a smaller turbo to work with the bigger TV that I have. At a later time, I could sell my TV, and buy a more modern turbocharger. There must be something better, its been 26years since that publication. In terms of the smaller turbocharger, I have heard that "too small" of a turbocharger can restrict the exhaust flow of the engine, so whatever it is, it should probably be bigger than a T04B98, and smaller than a TV series.

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I am not necessarily looking to make horsepower, only boost to keep the dedicated supercharger from sucking power from the engine. I need about 8PSI boost at lower rpm's to equalize pressure on both sides of the blower. I am not a turbo expert but you ask a very interesting question.

I once thought about the math involved but the simplest idea is to split the difference. Go a few sizes down from the factory standard for your power setting and then spec a smaller turbo that can make up the difference.

In theory the smaller one should spool up fast and build boost on the low end and then the larger turbo spins up as the RPM's climb giving you full boost.

compound turbo sizing gas engine

I don't have the time to analyze the graphs at the moment but I must say you are doing your homework quite well. I would like to know what you come up with and if I get the chance I might try to crunch some numbers as well. Think about this. Turboed DD engines did go to a by.Compound Turbo Sizing Math. TDI s : '03 Wagon. Turbo sizing is a bit of a black art, to begin with, there are very few people out there that can size a set of sequential's properly, without the trial and error method that most rely on and those people aren't talking.

There are one maybe two people on this site that I know of that would have a decent grasp on the math, and background that would have a decent shot at it. I am not one of these people. I have been fortunate to have been around sequential diesel's since I was born, and have a decent idea of the sizes that work well together, but I am by no means an expert, and I am not really willing to share publicly what I do know.

Search for any and all posts by TdiMeister and GoFaster on this topic. Read those threads start to finish. Then, read them backwards. Then, go to the Honeywell websites listed and do the same. Then, start sketching out your air mass needs you can find this by logging your Tdi with a vag com's MAF readings.

You need to know how much mass of air to move. Next, realize that the only thing that matters is mass balance. Then begin your sizing quest. You will learn enough from those guys and threads to tell what the tradeoffs are. All of them require sacrificing something. None of the real-world, available solutions are ideal.

They all involve big compromises. So then determine where you can let go of power, and what kind of powerband you can live with. You'll have a good start. Control mechanisms will be your bugaboo. You'll pretty much have to engineer some flaps and valving and actuators from the ground up. NIST applet.When it comes to turbochargers, everyone seems to be an expert after they install their first turbo. Countless times we have seen people giving very detailed advice to others when they have very little experience themselves.

Turbochargers are one of the parts of your vehicle that greatly determine how it performs. Last year we put together an article that highlights some of the pitfalls associated with doing research on forums, and how altitude affects turbocharger performance. We figured we would follow that article up and explain what a compressor map is and how to read it.

compound turbo sizing gas engine

By analyzing compressor maps, you can start narrowing down the size of the compressor you need for your application. If you have never seen a compressor map, it may be difficult to make any sense of it.

compound turbo sizing gas engine

There is a lot of information contained within the map and before we get into the map itself, lets identify the two axis. The bottom axis represents the corrected mass flow.

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This is how much air the turbocharger flows per unit of time. This could be rated in Kilograms per second or pounds per minute these are the two most common. Vertical Axis. The vertical axis represents the pressure ratio of the compressor.

It is calculated by taking the absolute outlet pressure and dividing by the absolute inlet pressure. Note, most gauges read in gauge pressure i. Due to how this is calculated, there are no units associated with this axis. If you are familiar with a topographical map, then the data may look familiar.

As the efficiency increases, the rings get smaller and smaller. Within the turbocharger industry, these rings are called efficiency islands. The efficiency of a turbocharger is measured by its ability to compress the air without adding excessive heat.

The higher the efficiency, the cooler the outlet temperature for a given boost pressure it will still be above ambient temperature. These are both 76mm turbochargers. The difference is the one on the right has a map-width enhancement groove. If you notice, at lower pressure ratios, both turbochargers flow about the same, but as the pressure ratio increases, there becomes a distinct difference between the two. There are critical areas to be aware of on a compressor map. The surge line of a compressor map is the left hand boundary.

This line represents the maximum amount of pressure the turbocharger can produce while flowing the least amount of mass air.

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As the throttle is lifted while under load, the pressure that is built up in the piping system needs to be discharged. This type of surge is more severe on engines equipped with a post turbo throttle body. Throttle bodies are mostly used on gasoline applications, but with newer emissions standards, more diesel engine manufacturers are using them as part of their emission control strategy.

This is also what drove the need for aftermarket external blowoff valves.

Turbocharger Basics - Choosing The Right Turbo

These help discharge the pressure that is built up within the piping system allowing the turbo speed to decrease at a more gradual rate, which helps extend the turbo life. This is meant for nothing, but top end performance.

Most performance enthusiast want more power so up-sizing to a larger turbo s is the norm.A turbo-compound engine is a reciprocating engine that employs a turbine to recover energy from the exhaust gases. Instead of using that energy to drive a turbocharger as found in many high-power aircraft enginesthe energy is instead sent to the output shaft to increase the total power delivered by the engine.

The turbine is usually mechanically connected to the crankshaftas on the Wright R Duplex-Cyclonebut electric and hydraulic power recovery systems have been investigated as well.

As this recovery process does not increase fuel consumptionit has the effect of reducing the specific fuel consumptionthe ratio of fuel use to power. Most piston engines have a hot exhaust that still contains considerable undeveloped energy that could be used for propulsion if extracted.

A turbine is often used to extract energy from such a stream of gases. A conventional gas turbine is fed high-pressure, high-velocity air, extracts energy from it, and leaves as a lower-pressure, slower-moving stream. This action has the side-effect of increasing the upstream pressure, which makes it undesirable for use with a piston engine because it increases the back-pressure in the engine, which decreases scavenging of the exhaust gas from the cylinders and thereby lowers the efficiency of the piston portion of a compound engine.

Through the late s and early s one solution to this problem was the introduction of "jet stack" exhaust manifolds.

compound turbo sizing gas engine

These were simply short sections of metal pipe attached to the exhaust ports, shaped so that they would interact with the airstream to produce a jet of air that produced forward thrust. Another World War II introduction was the use of the Meredith effect to recover heat from the radiator system to provide additional thrust. By the late-war era, turbine development had improved dramatically and led to a new turbine design known as the "blowdown turbine" or "power-recovery turbine".

This design extracts energy from the momentum of the moving exhaust, but does not appreciably increase back-pressure.

This means it does not have the undesirable effects of conventional designs when connected to the exhaust of a piston engine, and a number of manufacturers began studying the design. The first aircraft engine to be tested with a power-recovery turbine was the Rolls-Royce Crecy. This was used primarily to drive a geared centrifugal supercharger, although it was also coupled to the crankshaft and gave an extra 15 to 35 percent fuel economy.

Blowdown turbines became relatively common features in the late- and post-war era, especially for engines designed for long overwater flights. It was realized in many cases the power produced by the simple turbine was approaching that of the enormously complex and maintenance-intensive piston engine to which it was attached. As a result, turbo-compound aero engines were soon supplanted by turboprop and turbojet engines.

Some modern heavy truck diesel manufacturers have incorporated turbo-compounding into their designs. Starting with the season, Formula 1 switched to a new 1. The MGU-H uses a turbine to drive a generator, converting waste heat from the exhaust into electrical energy that is either stored in a battery or sent directly to an electric motor in the car's powertrain.

Electric Turbo Compounding ETC is a technology solution to the challenge of improving the fuel efficiency of gas and diesel engines by recovering waste energy from the exhaust gases.

From Wikipedia, the free encyclopedia. Reciprocating engine combined with a blowdown turbine. Main article: Electric turbo compound. Popular Mechanics : — Retrieved 19 February October Archived from the original PDF on 16 February Archived from the original PDF on Flight : —


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