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Speed Secrets: 5.3 LM7 Cam and Intake Test! How good is the TBSS manifold

What kind of power gains can you get when you upgrade both the camshaft and intake manifold on a 5.3-liter engine? That’s what the team at Speed Secrets set out to find out, working with the experts at COMP Cams. What’s really cool about the experiment on this is, we get to look at the power gains from the combo, but we also get to see the gains they didn’t get. Does that sound confusing? The tests will clear everything up!

Using a 5.3-liter LM7 as a test engine, the team started with an engine that was basically stock. It has a stock bottom end, and stock heads. The only initial upgrades made were the valve springs 92mm throttle body, and it also had a TrailBlazer SS intake. All the combinations were also run with the same long tube headers, as well as a FAST XFi management system. 

The stock cam test showed a result of 359-horsepower and 384 lbs/ft of torque. Now to the good stuff, after installing a COMP 54-454-11 camshaft. With this healthy cam installed, the power output jumped to 466-horsepower and 418 lbs/ft of torque. 

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With the cam installed, it was time to upgrade to a FAST LSXRT intake manifold. With this next modification installed, the engine produced 479-horsepower and 422 lbs/ft of torque. Keep in mind, the TrailBlazer SS was already as really good intake for the engine, and offered more flow than other intakes available for the 5.3-liter engines. 

Still, the gains from the intake might not have been as much as you’d expect, but why? Basically, the intake manifold is outflowing the stock heads. So this goes back to why its interesting to look at the results they didn’t get. The next step should be upgrading the cylinder heads, and this will mean huge gains on top of what you’d get from a head swap alone, since the intake will be able to offer maximum benefits at that point. 

Get more industry insight on horsepower here:

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