All About Turbochargers – Part 3: Components of a Turbo Kit

There are several parts that make up a turbocharger system, and in this article we’ll talk about each part in detail. When you buy a turbo kit from most manufacturers you’ll get many components in that big box other than the turbocharger itself. What manufacturers will include will vary, but here is what you’ll normally see in your turbo kit. If you’re buying a kit for a non-turbo car you’ll see a new exhaust manifold in your kit. You’ll get one of two styles of manifolds: equal length or log style. An equal length manifold will help build pressure more efficiently as it will time the exhaust pulses to not only scavenge (where a pulse will drive another), but also ensure that each pulse does not interfere with the other. A log manifold is simpler, cheaper, and usually cast, but not always. There is a camp in the turbo world that discounts the scavenging effects of exhaust-pulse timing. The “scavenge naysayers” believe that more exhaust mass is better if you’re not going for peak horsepower. You’ll also see a downpipe, which leads from the exhaust of the turbine housing to the rest of your exhaust system. If your turbo does not use an internal wastegate … … then you will see a manifold with an extra port before the turbo flange and an extra pipe on the downpipe. This is for the external wastegate you now see before you. These can be far more precise and offer more tuning options for boost control. Inside the wastegate is a spring and a diaphragm. The spring will not move until there is enough boost pressure to overcome the spring and open the valve to bleed off exhaust gases. However, you can also control this with a boost controller, and your kit may have this as an option. You can have a manual boost controller or an electronic boost controller that uses solenoids, but either way, the controller limits how much boost pressure actually reaches the wastegate to keep it closed longer, and allows the turbo to create more boost pressure than what the wastegate spring normally allows. You’ll get more detail on these controllers in part six of this series. On the compressor side you’ll either see piping that leads to the intake, much like the Banks Turbo does for its basic YJ kit, or you’ll see this large radiator looking thing. That is what’s known as an intercooler and there are two different types: Air-to-Air or Air-to-Water. In most kits you’ll see an Air-to-Air, which uses ambient air to cool down the boosted air. When you increase air pressure you also increase its temperature, and you’ll want to cool this air before it gets into your engine. You can run a turbo with no intercooler, and many manufacturers have in the past, but you’re normally limited to just 7 psi of boost or lower depending on how your engine is set up. We’ll get into intercoolers in detail in the next article as they are an interesting topic on their own. Another part you’ll see on the pressure side of the turbo system is a blow-off valve. A blow-off valve opens when you close the throttle body to relieve the pressure from the boost side of the turbo. If you didn’t have this valve, you would get compressor surge, and could damage the compressor wheel, bearings, shaft, or all of the above. There are two types commonly used. One vents to the atmosphere, and the other allows pressure to recirculate. We’ll talk more about blow-off valves in part 5. Finally, you’ll see new fuel injectors, and either a … stand-alone ECU …

piggy-back ECU …

… or a programmer to reprogram your OEM ECU. You’ll need these because you’ve increased the volume of air going into your combustion chamber, and you’ll need to fuel it somehow. Normally your stock injectors will be insufficient as you’ll start to peak them out before you hit boost. The stand-alone, piggy-back, or programmer will allow you to program new fuel injector and spark maps to compensate for the larger injectors and increased air pressure in the combustion chamber. Next up, we’ll look into intercoolers and how they differ from one to another. It’s more than just air-to-air versus air-to-water.