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What Is A Twin Turbo Engine?

November 08, 2022  -  Engines & Components

7 People Found This Article Helpful
1982 Olds Cutlass

Turbos are known for making things faster. You can find turbo blenders, vacuum cleaners, and even razors. Slap the word ‘Turbo’ onto something, and suddenly, it’s purported to be fast, efficient, and powerful. But when it comes to automotive applications, things start to get very serious, very quickly.

We’re going to explain everything you need to know about a certain term that you may have come across on turbocharged vehicles, and that’s the twin-turbo. What is a twin turbo? What does this mean? How do twin turbos work? Why go twin-turbo? We’ll break it down for you.

If this article gets your motor revving and you want to fit twin turbos to your ride, just check out what we’ve got. Of course, you need a lot more than just turbos, especially if your engine wasn’t already turbocharged, and we’ve got you covered with turbocharger kit options too.

What Is A Twin Turbo Engine?

A twin-turbo engine is one that basically has twin, or two, turbochargers. These two turbochargers may be identical in make, model, size, and specification, or they may be different. They may also be installed in different ways, which we will get into shortly.

Is there anything more extreme than twin turbos? Aren’t two enough? Well, not quite for some manufacturers. Audi used a triple turbo setup on a V8 in the SQ7, as did BMW with a triple turbo setup on their 3.0L in-line six-cylinder diesel engine.

What about four turbos? Yes, there are a handful of cars with that, and the most prolific are the Bugattis. Bugatti’s fearsome 8.0L W16 utilizes quad turbos to feed copious amounts of air and make those four-figure horsepower outputs. BMW also flirted with four turbos on the 3.0L in-line diesel six, for the 750d.

How Do Twin Turbos Work?

There are a few ways in which a twin-turbo setup might work, and it’s not always the way you’d expect.

  • The parallel twin turbo setup, most commonly used in V-orientation engines such as V6s, V8s, V10s and V12s, sees two identical turbochargers feeding a bank of cylinders each. This is the earliest form of twin turbocharging, and the simplest in terms of exhaust piping.
  • Series twin turbo setups place the two turbochargers in series. A smaller first turbocharger may send compressed air into a larger second one, which compresses it further before sending it to the engine.
  • The sequential twin turbocharger setup is becoming popular, as it offers supreme versatility over the other two setups, and sees the use of two turbochargers, where a smaller one is used at lower engine speeds, and as the revs rise, the second larger one takes over, or both may simultaneously provide boost under high revs and loads.

Benefits Of Twin Turbos

Let’s take the benefits of each type of twin-turbocharged setup individually and look at them, as well as some of the downsides.

  • A parallel twin turbo setup offers the most efficient packaging within the engine bay and the least amount of exhaust piping. It also enables the engine manufacturer to use smaller turbos instead of a single larger one. Larger turbos take longer to spool up, leading to turbo lag at lower revs. A parallel twin turbo setup will still suffer from some turbo lag at lower revs until the turbos have sufficiently spooled up. However, it’s the most cost-effective solution.
  • A series turbo setup can be harder to dial in, as you need to ensure that the boost is carefully controlled to avoid damage to the second turbocharger and engine. However, it can be a great way to minimize turbo lag to a large extent, as the first turbocharger will, in effect, pre-charge the second one. This is similar to the Twincharger setups in some engines, where a supercharger is used in place of the first turbocharger.
  • The sequential twin turbocharger setup is fast gaining popularity among manufacturers, as it allows them to almost eliminate turbo lag when correctly dialed in. Sequential turbocharger setups can provide meaningful boost from as low as 1,800rpm, which is great in stop-and-go traffic, an area in which parallel setups can significantly underperform. However, sequential twin turbochargers are the most complex setup, require the largest amount of inlet and exhaust piping, and can be expensive to diagnose and fix when things go wrong.

Where To Buy And Cost

Where can you buy a twin-turbo setup or turbo kit from? Well, we’ve got a great range in stock for starters as well as components to help you build a custom setup for your application. Our experts can guide you towards the best setup for your car.

How much does a turbocharger kit cost? You’re looking at several thousand dollars, basically, especially if your car didn’t come turbocharged as stock. It isn’t as simple as slapping on a turbo and calling it a day.

Things To Keep In Mind When Turbocharging

Here are some precautions that you should bear in mind when upgrading your turbo, or turbocharging a naturally aspirated engine.

  • Can the engine handle the increased boost pressures? Will you need to beef up certain components?
  • What about the clutch, transmission, differential, and driveshafts? Can these support the increased forces that they will be subjected to?
  • Don’t just dial up the boost to the maximum at first, but incrementally turn it up.
  • Increased fuel is required as boost builds, as well as proper ignition timing, which is reduced as boost increases.
  • Always seek expert advice from those who know about forced induction. This is an avenue that could end in tears if you just slap on a large turbo, turn up the boost, and floor it.

Turbocharge Your Ride With JEGS

 JEGS can help you turbocharge your ride across all aspects, making it go faster, stop quicker, corner harder, look wilder, feel more luxurious — you name it. Since 1960, when founder Jeg Coughlin started the company, we’ve been committed to providing the best brands to enthusiasts across the country. Our physical store remains in Columbus, Ohio, and you can also shop online. Amazing prices, top-notch after-sales support, and expert advice are some of the many things that our customers can enjoy.

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