What is a twin-turbo engine?

Earlier this week in our news roundup we touched on the fact that Toyota had recently filed a patent for a new twin-turbo V8 engine. No one knows exactly which car or truck it’ll go into or if it will ever even come to fruition, but excitement is high among drivers who can appreciate this type of power in their ride. We’ve discussed turbocharged engines before and what they can lend to the driving experience, but today we’re delving into twin-turbo engines and how they can affect your drive time just in case this new patent ever makes its way into the lineup. Check it out.

What is a twin-turbo?

If you recall, a turbocharged engine is an engine that uses turbine power and forced induction to push extra compressed air into the engine’s combustion chamber. Why? Because this extra air means that extra fuel has to be pushed in as well (to maintain the fuel/air ratio), and you get a boost in power. The extra fuel combusts at a faster rate than a normal engine, so you can put the pedal to the metal. You’ll find this type of engine available in the iconic Orlando Toyota Supra.

The most common twin-turbo configurations

A twin-turbo, on the other hand, is when you actually have TWO turbochargers pushing extra compressed air into the combustion chamber. The turbochargers can be different sizes and can be laid out in different configurations. Here are the three types of setups you’ll typically see:

• Parallel: This is when there are two turbochargers of the same size are situated parallel to one another and each turbocharger receives half of the extra exhaust gases. This layout is best suited to V6 and V8 engines because each turbocharger can be assigned to one cylinder bank and reduce the amount of exhaust piping needed. Parallel twin-turbo engines reduce lag, which can be an issue in turbocharged cars, by using two smaller turbo chargers instead of one large one.
• Sequential: Sequential twin-turbo engines utilize one turbocharger for lower speeds and one turbocharger (or sometimes both) for higher speeds. This setup is supposed to offset the issue where turbochargers are unable to provide a boost of power when RPMs are low. Typically, a smaller turbocharger is used for a boost at low speeds and a larger turbocharger is used for a boost at higher speeds.
• Series: This type of twin-turbo setup is when the turbochargers are set up in a series (go figure). The output from the first one is then further compressed by the second one. This leads to much higher pressure and boost than you’d normally get.

We have no idea which setup (if any of them) the new Toyota V8 engine will utilize; rumor has it that right now, it will be a “hot v” configuration where the turbochargers are actually mounted in between cylinder heads and the flow of fresh charge and exhaust gases is reversed. We’ll have to wait and see what’s unveiled in the coming months.

If you have questions about turbochargers, twin-turbo setups, or just engines in general, call us! Toyota of Orlando is open seven days a week at (407) 298-4500 and we’re located just off I-4 across from the Millenia Mall.

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