Turbo swaps seem like a daunting and difficult job. However, the MQB platform makes it nothing more than a weekend job. A turbocharger, or turbo, uses exhaust gas to spin a turbine wheel that forces extra air into the engine by compressing it. More air means more fuel and a bigger bang, which leads to more power. A bigger turbo can move more air and unlock more power, but sometimes bigger doesn't always mean better.The IHI (Ishikawajima-Harima Industries) IS12, IS20, and IS38 are all factory turbos built for the same family of Volkswagen and Audi engines, known as the EA888 Generation 3. Because they share the same basic design, a turbo from a high-performance Golf R can bolt onto a base-model Golf with only minor changes. I break down which turbo fits which goals, what parts the swap requires and why professional installation still matters even though the hardware fits easily.Related ReadingsHow Does a Turbo Work? The Science Behind Boost and AirflowTurbo Wastegate Adjustment on MQB IHI TurbosTurbo Overboost: Causes, Symptoms, and How to Diagnose ItDo You Need a Tune for a Cold Air Intake? What You Should KnowDoes a Cold Air Intake Improve Gas Mileage? What the Data ShowsWhich Cars Use the IS12, IS20 and IS38 TurbosThese three turbos are ranked from smallest to largest: the IS12, then the IS20, then the IS38.The IS12 is the smallest of the three. It comes standard on the 1.8-liter turbo engines used in the Volkswagen Golf, Jetta, and Sportwagen or Alltrack, along with the Audi A3.The IS20 is the midsize option. It comes on the 2.0-liter turbo engine found in the sportier Volkswagen GTI and GLI, along with some Audi A3 models.The IS38 is the largest and most powerful of the three. Volkswagen and Audi use it on their highest-performance versions of the same 2.0-liter engine, including the Golf R, Audi S3, and Arteon.How Easily These Turbos InterchangeBecause all three turbos bolt up to the same family of engines, swapping a bigger one onto a smaller car is fairly simple. A base 1.8-liter Golf can accept the midsize IS20. A GTI can move up to the largest IS38, the same turbo used on the Golf R.The physical part of the swap is straightforward and can be done in a driveway with common hand tools. But bolting on a bigger turbo is only half the job.After any turbo swap, the engine's computer needs new software, called a tune, to safely use the extra airflow. A few supporting parts usually come along with it. I typically require both a downpipe, which is a wider exhaust pipe right after the turbo, and an upgraded intercooler, which cools the compressed air before it enters the engine. The parts bolt on easily, but getting the tune right is what actually makes the extra power safe and usable.When doing a turbo swap, an install will be required; parts include:(ECS tuning kit)06L253039A - Manifold to Turbo Gasket5Q0253115B - Turbo to DP GasketN90067202 - Turbo Oil Line Gaskets (x2)N91231701 - Turbo Mounting Studs (x4)WHT007210 - Turbo Mount Nuts (x4)WHT006112 - Turbo Oil Line GasketWHT006113 - Turbo Oil Line GasketN91103701 - Turbo Mount BoltN90643907 - Turbo Mount BoltN91167101 - Hex BoltN10699401 - Hex BoltN91201001 - Hex BoltWHT006114 - Coolant Hose O-RingWHT006124 - Coolant Hose O-RingWHT005558 - Coolant Hose O-RingHardware Needed for an IS-Series Turbo SwapRemoving an old turbo and bolting on a new one means replacing a lot of small connecting parts along the way, not just the turbo itself. A proper install calls for a full gaskets and hardware kit rather than reusing old parts. Gaskets are thin seals that keep oil, coolant, and exhaust gas from leaking out of a joint. The kit includes several gaskets, mounting bolts, mounting nuts and coolant hose seals.Owners who want the most power out of an IS38 sometimes switch to E85, a fuel blend with a much higher ethanol content than regular gasoline. That upgrade path calls for a bigger fuel delivery system, including additional fuel injectors (MPI), an upgraded fuel pump (LPFP) and a flex sensor that tells the engine's computer how much ethanol is in the tank. That combination pairs with TuneZilla’s flex fuel tunes to unlock significantly more power than gasoline alone allows.Understanding Spool and Turbo LagSpool time is how long it takes a turbo's wheel to spin up to full speed once you press the gas. Turbo lag is the short pause you feel between pressing the accelerator and the extra power actually arriving.A smaller turbo, like the IS12, spins up almost instantly because it takes less exhaust flow to get moving. That means quick, responsive power right when you touch the gas, though its overall power ceiling is lower. A larger turbo, like the IS38, needs more exhaust flow to reach full speed, so it takes a bit longer to build power. Shifting to a lower gear can help, since it raises engine speed, or RPM, into the range where a bigger turbo works best.In practice, a 1.8-liter engine with the small IS12 feels lively and responsive from a stop. A 2.0-liter engine with the larger IS38 takes a moment longer to build boost but pulls much harder once it does, especially at higher speeds. All three are factory-engineered, meaning original equipment manufacturer (OEM) parts, so reliability and everyday drivability stay strong no matter which one is under the hood.Choosing Between Top-End and Low-End PowerLow-end power means strong acceleration right away, from a stop or at cruising speed. Top-end power means the engine keeps pulling hard as engine speed climbs toward its limit. The right turbo depends on which kind of driving you do most.Drivers who spend a lot of time on the highway, where higher engine speeds are common, tend to prefer the larger IS38 for its stronger pull at higher RPM and speed. Drivers stuck in frequent stop-and-go city traffic often prefer the smaller IS20 instead. It delivers strong power at lower engine speeds without the extra lag that comes with the biggest turbo in the lineup, which suits the way most daily driving actually happens.Comparing Turbo Size and AirflowThe size of a turbo's internal wheels explains most of the performance difference between these three units. A bigger wheel can move more air, but it also needs more exhaust energy to get spinning.The IS12 has the smallest wheels of the three, so it spins up quickly but runs out of airflow sooner, capping its power potential. The IS20 has noticeably bigger wheels, letting it move more air at the cost of a slightly slower initial spin-up. The IS38 is bigger still, needing more exhaust energy to get moving but rewarding that patience with substantially more airflow once it does. That extra airflow capacity is exactly what separates GTI-level power from Golf R-level output.Why an OEM Turbo Upgrade Is Worth ItUpgrading to a bigger factory, or OEM, turbo is one of the most accessible modifications available on these platforms. Since the parts share the same basic design, little or no custom fabrication is needed to make the swap work.Aftermarket turbos exist too, including upgraded IS38-based units from builders like Precision and Turbo Concepts. Most of those are still built on the original OEM housing, so they bolt on just as easily using the same supporting hardware.There is no better upgrade path for a 1.8-liter or 2.0-liter engine than a bigger OEM turbo paired with a proper TuneZilla tune behind it.
