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Speed Secrets: Does a Larger Throttle Body REALLY Gain Horsepower?

Working with the experts at FAST, it’s time to talk about airflow – not just any airflow, but throttle body airflow. There’s a lot of misunderstanding around the engine building community about intake manifolds and throttle bodies. When a FAST intake manifold was tested against a stock manifold, you’ll see big gains – the misconception is that those gains are coming from the larger throttle body over stock. While the throttle body is bigger, the gains are not coming from the throttle body, but the manifold – to prove this, it’s time to put it to the test.

To test the effects of throttle body airflow, it’s time to hit the dyno with a test engine. The engine is using rectangular style cylinder heads and a factory LS3 intake manifold. To improve the health of the test engine, the crew installed a 54-469-11 COMP Cams camshaft with a
.617/.624 lift, a 231/247 duration, and 113 LSA.

Now that the airflow is taxed with the larger cam, the engine is put to the test with the factory LS3 intake and a FAST 92mm throttle body – FAST also supplied coil packs and higher flowing fuel injectors. Run first with the LS3 and 92mm throttle body, the engine produced 546-horsepower and 494 lbs-ft of torque.

Stepping up to the 102mm throttle body. Amazingly, installation of the larger throttle body had no impact on the horsepower and torque. That’s not to say that a larger throttle body doesn’t improve airflow, but you need to change the intake manifold to actually take advantage of that airflow. Once the air increases, it’s actually the intake doing most of the heavy lifting!

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