Build Turbo Kits

Learn How To Build Turbo Kits

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Learn How to Build a Turbo Kit

Welcome to the Learn how to Build Turbo Kits web site. This site teaches you everything you need to know about building turbo kits for almost any fuel injected engine. The web site is intended to educate the reader in all aspects of turbocharging for extreme horsepower.

This website contains pages of information about turbocharging, so scroll down below the table of contents and start learning. Please share our site with the turbo community and on turbo forums. We would love to see turbo kits being built in garages around the world because of this web site!

The knowledge gained from reading this information should help you to make informative decisions concerning turbocharger selection, engine build configuration, fuel system upgrades, PCV solutions, PCM tuning and upgrades, turbocharger system fabrication and much more.

If you intend to turbocharge your vehicle by means of an off-the-shelf kit, or by fabricating your own system, this web site will provide you with a wealth of knowledge that will help you obtain your goals.

Please note that all material contained on this web site are copyrighted. Any unauthorized use of the information provided on this site will be considered copyright infringement, and an injunction will be filed.

This website covers the following turbocharging topics. Scroll past the table of contents to begin chapter 1.

Chapter 1: Basic Turbo charging Concepts

Chapter 2: Selecting a Turbocharger

Chapter 3: Turbocharger Systems and Components

Turbo chargers

Waste gates

BOV

Headers

Boost Control

Chapter 4: Intercooling

Air to Air Intercooling

Air to Water Intercooling

Alky Injection

Chapter 5: The Hot Side

Manifolds

Stock Manifolds

Log Style Turbo Manifolds

Custom Tubular Headers for Turbos

Turbo Downpipes

Chapter 6: Turbo Oiling Systems

Turbo Oil Feed

Turbo Oil Return

Tapping the Oil Pan for Turbo drain tube

Scavenge Pumps

Sumps

Chapter 7: Fuel Systems

Stock Fuel System Limits

Fuel Pumps

Fuel Injectors

Return Type System

Chapter 8: PCM Tuning

Dyno Tune

Software

Standalones

Piggy Backs

Speed Density

MAF Limitations

Tuning Basics

Chapter 9: Internal Engine Modification

Camshaft

Cylinder Heads

Pistons

Crank/Rods

Intake Manifold

Chapter 10: PCV Systems

Modifying the PCV System for Boosted Applications

Chapter 11: Turbocharger Mounting Locations

Conventional Mounting

Rear Mounting

Chapter 12: Keeping an Eye on Things (Gauges)

AFR Air Fuel Ratio

Boost

EGT Exhaust Gas Temperature

Fuel Pressure

Chapter 1 -Basic Turbocharger Concepts

Here are some basic concepts and formulae that you should know before delving into your turbo project.

Selecting a turbo size to match your engine is not at all difficult. You need to find a few things about your engine, decide how much boost you want to use, and then plot the information against a turbocharger's compressor map. There is a little bit of math involved, but it’s easy.

First you need to know the CFM of your engine when running naturally aspirated. You can find this by using the following formula:

volume of air (cfm) = engine rpm x engine cid
                                3456

So, an example engine with 350 cubic inches of displacement would look like this:


volume of air (cfm) = 6000 x 350 = 2100000 = 607.639
                        3456          3456

The engine in this example needs about 600cfm of air at 6000 RPM naturally aspirated. Now we know our NA cfm requirements, but in order to read a compressor map we'll need to figure out the airflow in pounds per minute (lb/min) required by our engine under boost. For our example, let's use a boost pressure of 10psi.

At this point it is important to talk about the difference between absolute pressure (psia) and gauge pressure. The boost level that you read on your boost gauge is really called psig or pounds per square inch gauge. The absolute pressure is 14.7 + psig. The 14.7 comes from the pressure of air at sea level. So 10psig = 24.7psia.

We can find our engine's requirements by plugging our numbers into the ideal gas law. The ideal gas law relates volume, pressure, temperature and mass of air. It is:

PV = nRT

Where P = absolute pressure, V = volume cfm, n relates to mass, R is a constant and T is the air temperature in Rankine.

Let's simplify the ideal gas law to find our engine's required airflow in lb/min with 10psi boost. We will need to know the temperature of the compressed air coming out of the turbo. Let's assume an intercooled intake air temperature of about 130F. Turbo cars that do not have an intercooler can see intake air temperatures around 250F. To get the temperature in Rankine, simply add 460 to the air temperature in F.

     n(lb/min) = (14.7 + psig) x V cfm x 29
                    10.73 x T deg R

           n(lb/min) =(14.7 + 10) x 600 x 29 = 24.7 x 600 x 29 = 429780 = 67.888 lb/min
                       10.73 x (130 + 460)R     10.73 x 590R     6330.7

We find that ideally, our engine will require 67.9 lb/min of air under 10psi boost at 6000RPM. I say ideally because that assumes our engine has a volumetric efficiency of 100%. We'll assume that our engines have a volumetric efficiency of about 85%. Now we can correct our airflow.

67.9 x .85 = 57.7 lb/min

By the way, as a rule of thumb, horsepower can be found by the following:

Hp = airflow lb/min x 10 = 57.7 x 10 = 577

Now that we know our required airflow in lb/min, we need to find something called a pressure ratio. This is the ratio between the inlet and outlet pressure of the turbo's compressor. Inlet pressure is usually 14.7psi. (standard barometric pressure at sea level) The outlet pressure is 14.7psi + boost pressure. Take the ratio of the two and you get:

Pressure Ratio = 14.7 + boost
                    14.7

We decided to run our project at 10psig. That gives us:

Pressure Ratio = 14.7 + 10 = 24.7 = 1.68
                  14.7       14.7

We now have all the of the information that we need to read a compressor map. Let's take a glance at a few and see what compressor will work best with our application.

The maps show both efficiency and RPM curves for the compressor.
In order to read the maps, simply find the pressure ratio on the y-axis and follow the map over to where the airflow meets the engine airflow.

turbocharger compressor map

The map above is for a Garret T04E compressor in 60 trim (we'll talk about trim later). Notice the islands on the graph that look like ripples on water. Those are efficiency islands. It is desirable to have our point plotted right in the middle of the graph, although anything down to about 60% efficiency will work. Notice that our point is way off the map for this turbo. The turbo will still make boost, but will not be efficient. This is a bad selection for our project.

Our point is off the map to the right. What if our point fell in the surge limit area to the left? That would be very bad. In fact, it would surely cause damage to the compressor. In this area, the air flow is unpredictable and changes direction.

Let's look at another turbo compressor map.

This is a map from a T76 compressor. Notice that the point lands right in the 70% efficiency island. This would be a perfect turbo for our example project. But there are other things to consider when sizing a turbocharger for your engine.

We've talked a lot about the compressor side of the turbo, now let's turn to the turbine side. We've shown that a T76 will work for our project, but will spool? That depends on the area ratio (A/R) of the turbine housing, and the turbine size. A larger turbine wheel will spool slower than a small one. A larger turbine will make more power, but it will come on later, maybe when the race is over.

Turbo Charger Area Ratio A/R - Next Page >>