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Speed Secrets: FAST Intake Manifolds Short Intake Runner Test

The LSXR LS3 intake manifold is the result of extensive EFI research and development by Fast, the industry leader in fuel injection aftermarket performance parts. More flow and more power are among the many benefits this incredible intake manifold has to offer, but it doesn’t end there.

The really great part about the FAST LSXR LS3 intake is its adjustability that is made possible with interchangeable runner sections. This means that you can tailor this intake to perfectly fit the needs of your application. If the goal for your build is big power down low, this intake can be fitted with long intake runners. However, if you’re looking to push that power to the upper limit then the short runners are just what you need. To explore how the Fast LSXR intake runner interchangeability lets you dial in the effective operating range of your combination, Richard Holdener with Speed Secrets teams up with Fast on a 408 Stroker build. 

The low compression 408 Stroker featured a healthy COMP camshaft, LS3 heads, and a FAST 102 LSXR manifold. Fast also supplied a set of injectors and a big mouth throttle body.

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Because the goal was to extend the RPM range of the 408, the shortest runners Fast had to offer were chosen for this build. Equipped with the Fast manifold set up with the short runners the engine produced 547 HP @ 6,800 RPM and 493 Lb-Ft of torque @ 5,300 rpm. That is an impressive start and because of the low compression ratio, this application is a perfect candidate for boost. Richard then installed a D1SC supercharger from Procharger combined with an air to water intercooler and put the 408 back on the Dyno where it produced 846 HP @ 6,900 RPM and 682 Lb-Ft of torque @ 5,600 RPM with a peak boost of only 11.7 PSI.

The great benefit centrifugal blowers have over the rest is that the boost supplied by the blower increases with engine speed, and because of the short runners installed with the FAST the RPM range of the 408 was extended. Thus giving the Procharger more time to do its thing. The FAST LSXRs adjustability was truly invaluable to this build and because the boost peaked at only 11.7 PSI there’s plenty of room for more power with more boost. Good things really do happen when you combine short runner manifolds with plenty of boost. 

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