Turbo Tutorial

Ghetto Mods

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Mazdaspeed 3
Can anybody recommend a good resource to get smart on turbocharging?

I've picked up a few odds and ends here, but using search is gonna be unwieldy. I've got a lot to learn if I want to mod my motor so I'd like to start w/ the basics and move on from there.

Appreciate it.
 
Go to the book store and get Maximum Boost by Corky Bell. More info than you will ever need. Otherwise, you dont need to know a whole lot on this car until more options come out like the COBB AP. Just throw a few bolt ons on it and call it good for now.
 
Go to the book store and get Maximum Boost by Corky Bell. More info than you will ever need. Otherwise, you dont need to know a whole lot on this car until more options come out like the COBB AP. Just throw a few bolt ons on it and call it good for now.

We have a winner!

I visited Corky's shop and bought my copy from the man directly. (he signed it too. woo woo)...

Now....if only I had a car that was turbo'd. . .

By the way, it's well written in easy to understand language too....not just engineering speak.

--jason
 
taken from another forum ... brought to you by the Author = Boost Addict ...


A DISCLAIMER BEFORE WE BEGIN: This post is intended to help individuals understand Turbos. Though it may initially seem like an intimidating topic to some of you, I ask for your patience and open-mindedness. Just 6 years ago, I knew NOTHING about turbochargers or how they worked. It took many explanations and several different illustrations for me to understand. And even then, I wasn't completely comfortable with the process... It took a proper and patient explanation to completely sink in. Though turbocharging is a common process, I will be focusing on the MZR 2.3 DISI. Without getting too specific, I intend to introduce and describe the task and importance of each of the key components in the power plant. I will also cover some possible restrictions in the stock setup and go over potential modifications. This post will be here... Take it one bite at a time, and chew on it. I broke it down, so it's easier to digest. Take your time, learn the components, their duties, and soon you'll be addicted to it as much I am. So without further ado, let's get started.

What's A Turbo? - Essentially, a turbocharger is a unit that effectively compresses air using the exhaust gases of the engine. Compressed air is highly pressurized air in a small area (pounds per square inch). Theoretically the more psi an intake system delivers to the combustion chamber, the more fuel will be delivered to keep a safe Air/Fuel ratio. The stronger the combustion, the more power you make. Bear with me, it gets simpler. Assuming your ecu and fuel system are doing their job to compensate for changes, then the following is true: More Air = More Power.

Let's first take a closer look at the compressor itself. Here is an illustration that I found on the web. Credit to Jim Hatch for this excellent rendition that I modified to make more beginner-friendly.
jhatchmodbyboost1.jpg

What Makes Up A Turbo? - The anatomy of the unit may appear intimidating at first. It's really quite a simple contraption. Let's break it down. So the unit consists of two chambers. Each one houses a 'fan blade' set-up internally. These two fans are connected by the rotator shaft. So if one is forced to turn, the other will obviously turn at the same rate. So about those two chambers:

THE EXHAUST SIDE - Exhaust gases enter via the Up-Pipe to turn the fan blades and exit out the Down-Pipe.

THE INTAKE SIDE - Air is pulled in and compressed from the Intake. Exits to the Intercooler.

Intake Fan. Exhaust Fan. Attached with a Shaft. Ok, Got it! So How Does A Turbo Compress Air? - Assuming you're familiar with the way standard engines work, let's fast forward to post-combustion, when exhaust gases travel down the headers (or exhaust manifolds). In a Naturally Aspirated car, this is where your exhaust system begins... In a turbocharged engine, this is where Boosting Begins. The gases are routed from the manifold via the Up-Pipe into the EXHAUST SIDE of the turbo. The gases spin the fan blades VERY rapidly, I'm talking tens of thousands of RPM.

So if the Exhaust Fan is spinning, and its connected to the shaft... Then what else is spinning? That's right, the Intake Fan! The high-speed rotation of the Intake Fan creates a vacuum, which literally sucks air in form the intake, compresses the air, and sends it off to the Intercooler.
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So with this basic knowledge of how the turbo makes power, let's take a broader look at the process as a whole.

I've designed a diagram of the power plant with great emphasis in trying to keep it as Simple and Uncomplicated as possible. I do hope I've accomplished this effectively.

TURBOCHARGEDENGINEDIAGRAM.jpg

This diagram is spread and some components may not be in the exact location, but they are correctly placed if you follow the path. I did not diagram it out based on the stock system, because things are stacked and wouldn't be as easy to understand.

As I identify each component as the air passes through it, I will also note any possible restrictions and touch slightly on possible modifications. We should find ourselves more familiar with the turbo process once we exit the tailpipe. Starting at the upper left of the diagram, let's begin:

AIR-INTAKE SYSTEM:
What Does It Do? - Draws air in from the front of the vehicle.
Any Restrictions? - Yes. During full throttle, air is being pulled in very aggressively. The stock setup will have trouble pulling air efficiently during this demanding moment. Also, a narrow diameter poses as a restriction, as do ribs and bends that create turbulence and slow down the overall air flow.
What Can Be Done To Help? - There are already several Cold Air Intake options available, both from MAZDASPEED and the aftermarket. They are essentially larger diameter pipes with smoother flow properties and less restriction. The more power you demand from your car, the more you will benefit from an upgraded Intake system.

TURBO INLET HOSE:
What Does It Do? - Routes the air from the Intake to the Turbo Chargers Intake Side.
Any Restrictions? - Sure, it can. If the stock inlet hose is narrow or ribbed, it can create a disturbance in the efficiency of flow of air into the turbo. However, this has yet to be determined.
What Can Be Done To Help? - Silicon Inlet hoses generally offer a smoother air path that will allow the turbo to spool a few hundred rpm earlier (depending how restricting the stock one is). None are currently available at this time. Then again, it may not be a noteworthy upgrade for this car.

--At this point, the air enters the turbochargers Intake Side. While the air is compressed and pushed out, it also gets hot due to the naturally high temperature operation of the turbocharger itself. The air is guided through an intercooler hose and enters the next component.

INTERCOOLER:
What Does It Do? - Cools the hot air pushed from the turbocharger, making it more dense and suitable for effective combustion.
Any Restrictions? - Sure. An intercooler can always be improved to a more efficient unit. Is it necessary? It's arguable at stock power levels, so I'll leave it alone.
What Can Be Done To Help? - A larger core unit or one thats placed as a front mount can effectively reduce temperatures. Keep in mind that flow properties also play a role here. So when selecting an intercooler, be aware of its flow characteristics more so than its size.

--The air is then routed to the Intake Manifold via another Intercooler Hose. *A note about I/C Hoses - In some cars they can pose as restrictions because they are narrow and/or ribbed. Replacing little things like these with better flowing(and unrestrictive) silicone units can slightly increase their efficiency, cutting down slightly on the speed of the entire turbo-charging process (read - cutting down on lag).

--The Intake Manifold dumps the air into the Engine. Inside the Combustion Chamber, combustion occurs, depositing exhaust gases out of the Exhaust Manifold, or Header.

--The Speed3s Header has an unrestrictive and catless Up-Pipe(nice work, mazda), which really wouldn't benefit from replacing, unless you're running a huge turbo setup. The gases are then pushed into the Exhaust Side of the turbo and turn the fan blades rapidly creating a vacuum(boost) on the Intake Side (The process simultaneously continues on from the Intake Side). The gases then exit the turbocharger and dump into the next component.

DOWNPIPE (Sections A & B):
What Does It Do? - Routes exhaust gas from the turbo down to the exhaust system. Section A is essentially the Downpipe itself, and Section B may be referred to as the Secondary Pipe, or Test Pipe.
Any Restrictions? - Absolutely! On the Stock setup, there is one catalytic converter on the 1st section and another on the second. Aside from the cats, it's narrow and mangled design doesn't create a good opportunity for the gases to flow out freely and in turn create BACK PRESSURE. Back Pressure, is essentially caused by a 'clogging' or restricting of the flow of exhaust gases. This inhibits the fan on the exhaust side of the turbo to spin freely. So the turbo is working harder and making less power. A simple example: Take a narrow coffee mixer/straw, bend it in a few places, seal your mouth around it and blow hard. Feel the pressure exiting the other side... Not much right? Now take a regular diameter straw bend it conservatively and now blow. This demonstrates that a narrow, restrictive straw will make you work harder to blow a specific amount of air, while a freer flowing, larger diameter straw lets you blow with greater efficiency without blowing as hard. The EXACT same applies to Turbos. The easier the air exits, the easier the blades spin, the easier you create that boost.
What Can Be Done To Help? - A replacement of the entire Downpipe is what would be recommended. There is currently a racepipe that is on the market that deletes the second cat. It's a gain, sure, but you're still blowing through the coffee straw. That's like adding a big straw mid-way down the coffee straw. You're still straining. There will be lots of options available soon that will allow you to replace the full Downpipe with something far less restrictive. I recommend keeping one Cat, only because I prefer to run a cleaner, not-so-loud, non-smelly car. This does not mean keeping a stock cat. There are race-cats(or high flow cats) available with most Downpipe systems. At full throttle, a race-cat poses no measureable flow-restriction over a catless design (we're talking MAYBE 1 hp). There will be different designs to choose from: Bellmouth or Divorced Wastegate. It's a whole different topic to discuss. However, both will offer a huge gain over stock, and neither will pose as a restriction.

CAT-BACK EXHAUST SYSTEM
What Does It Do? - Continues to guide the exhaust gases collected from the Downpipe out the Tailpipe.
Any Restrictions? - Sure. You wouldn't want a coffee straw at the end of your regular straw would you? Again, a case of reducing backpressure. It's highly recommended that this be opened up.
What Can Be Done To Help? - There are several to choose from in the aftermarket. They will mostly all be 3 inch with mandrel bent pipes, which mean the diameter does not narrow during the bends and poses no restriction. Any 3 inch cat-back is a 3 inch cat-back, choose the sound you like best. As long as they are equipped with straight-flow mufflers, there will be no power difference worth mentioning.
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Congratulations! You got sucked in as air through the intake, got compressed by the turbos intake side, got cooled by the intercooler, and combusted in the engine. Then you left the engine as exhaust gas, ran through the turbos exhaust side to help create more boost, then left the turbo through the downpipe, through the catback, and out the tailpipe!

Again, I understand that this is a LOT of information. But I hope I've been able to deliver it in a more understandable manner. One that involves YOU in the process and guides you through each component. I also covered some possible restrictions and the modifications that would alleviate these restrictions to help create a more efficient turbocharged experience.

But there is one last thing I would like to mention, and that's the importance of engine management.

We now understand that we can allow the turbo to pull air easier by cutting down on certain restrictions from the intake end and exhaust end. But there's one important thing to keep in mind. Every flow measurement (air, fuel, timing, boost, etc...) is constantly being monitored by the ECU. It is programmed to run at specific Air/Fuel ratios. And the stock A/F ratio is VERY rich (meaning excess fuel). So even if you INCREASE the air coming in and assume its leaning out. Yes, it is, slightly... But the ECU will eventually correct itself once it detects an out-of-norm ratio, or a knock. This is why people are told to RESET their ECU after adding a modification. So as soon as you punch the throttle, you will feel a VERY notable difference... but as time goes on, that ecu will have retarded timing and adapted to the change.

My advice is simple: Each mod you add mentioned above will give you a gain. How much of a gain is to be taken with a grain of salt. Dyno's show an immediate pull, not an adapted pull. Take horsepower and torque graphs for what they are, but do not expect these gains to add up perfectly. Overtime these parts that you spend money on will no longer do what they used to, because your ECU will not allow it. Just because an intake is CAPABLE of drawing more air in, doesn't mean it will.

To get the MOST out of your mods, or even the most out of your vehicle in stock trim, invest in a good Engine Management option. This will allow you to run tunes SPECIFICALLY designed to work with components that allow a freer flowing exhaust, intake, etc... In other words, you will ACTUALLY be running a leaner map and taking full advantage of your mods, while maintaining stock-like reliability. I don't want to name drop, because people here already know my choice of tuner. And since this is an informational thread, I've tried my hardest to keep Brand Names out and Information in.

At this point, with the information I've provided, you should be able to decipher a good mod from a not-so-good one. You are now equipped with a basic understanding of turbocharging. You don't need dyno graphs or companies to tell you that something will give you a gain. All you need is your logical and understanding to simply determine whether or not a specific mod will truly make this process more efficient.

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I truly would like to thank anyone who spent the time to read this post as it took a lot of dedication and effort to plan, illustrate, write, and complete. It's near impossible to get it right the first time, so if anybody notices anything that needs correcting, please let me know and I will correct it immediately.

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PLEASE CONTINUE READING FOR A GREAT WRITE-UP ON THE FUNCTIONS/IMPORTANCE OF A BOV/BPV WRITTEN BY ROTUS8

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cont ....

Author = Rotus8
I would like to augment Boost's excellent description of turbo systems to include the bypass valve (sometimes called blow-off or BPV) function. I feel this is a mis-understood part of a turbo motor and an explanation is in order. I have added a few bits to Boost's diagram with his permission.

5x41o4o.jpg


The bypass valve is there to solve a specific problem with turbo engines. Imagine the engine is running at full boost. The turbo is spooled up supplying lots of air through the intercooler, through the open throttle plate, and into the engine intake. Now, suddenly close the throttle. The turbo is still spinning madly trying to shove air into the intake, but it can't get past the closed throttle. The pressure in the intercooler and related tubing rises dramatically and the turbo is forcibly stopped, if it doesn't blow one of the hoses first. Not good.

The solution is the bypass valve which opens in this case and bleeds this excess air back to the intake of the turbo. This allows the turbo to continue to spin so if the throttle is opened again, the boost can build quickly again when the bypass closes. It also prevents the damaging high pressures and shock to the turbo itself.

The control of the bypass valve is quite simple. There is a hose from the intake manifold to the valve. Inside the bypass valve there is a diaphragm with the intake pressure on one side and the intercooler outlet pressure on the other. The valve opens when the intake manifold pressure is lower then the supply pressure by a set amount. This amount is about 15 psi for the stock bypass valve in the MS3. When the throttle is closed with the engine revving, the intake manifold pulls a high vacuum quite quickly; the bypass will open rapidly. Remember the bypass is sensing the difference between the turbo pressure and the intake vacuum (negative pressure).

Notice in the diagram the position of the hose returning the bypassed air back to the intake. This air is returned between the MAF and the turbo. The purpose of the MAF is to measure the amount of air going into the motor so it can inject the appropriate amount of fuel. When the bypass valve opens, the air from the intercooler is dumped back to the intake of the turbo, supplying essentialy all the air the turbo is asking for. The flow through the MAF is stopped because no more air is needed. This signals the ECU to stop injecting fuel into the motor because since there is no net air going in, no fuel is needed.

If a BOV is installed that vents to air instead of recirculating back to the turbo intake, the turbo will keep sucking air through the MAF even though none is going into the motor. The ECU thinks air is still going into the motor so it keeps injecting fuel. This unneeded fuel is wasted, and can damage the motor by washing the oil off the cylinder walls.
 
Boost Addict's tutorial is very well-written, and was definitely helpful to me when I first started snooping around...i highly recommend you sit down and fully grasp all he has there before going nuts trying to figure out intimate details about how to mess with turbos! =d
 

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