Dyno Testing FAST's New LSX Intake Manifold - Suck It In

Here is a closer look at the 92mm Big Mouth throttle body. Besides being engineered specifically for the new intake, it touts:

Our cast of characters: The parts that went into this engine are, of course, the Comp cam and Edelbrock heads, along with the Painless wire harness, FAST LSX intake, FAST 92mm Big Mouth throttle body, and Hooker Super Comp headers for the LS1-LS7 engine.

Prior to installing the new intake, we put on a new set of intake seals that FAST provided to us for the build.

Stainless steel fasteners are provided with the LSX intake. It is just a matter of bolting them on.

Mena suggested we ditch the OE fuel rails in favor of an upgraded set. We didn't order new ones for this swap, but took his advice and used a set that Westech had at its facility. FAST also has a set of rails available for the LSX intake; however, we neglected to order these.

Sitting under the rails are the new 36-pound injectors. During our last round of tests with this engine, the stock 24-pound injectors had just about reached their limit. Bigger injectors are a must to keep up with the fuel demands.

One small problem we encountered during the set-up process was the injector wiring. The Painless harness we ordered was built for year-specific injectors. When we upgraded to the newer 36-pound FAST injectors, the harness was not equipped with the right clips. We were dead in the water, but Mena called a Chevy dealership, and $140 later we had a set of updated clips for the new injectors. Wow, those are some expensive clips.

Mena started to work by clipping off all the old clips from the harness and wiring in the new ones.

Yes, we realize that soldering the wires would have been better, but we had to settle for crimping them. Dyno time was wasting, and, as John Wayne would say, "We're burning daylight."

The one piece that we did pull off the old intake and reuse was this Manifold Absolute Pressure (MAP) sensor.

All these modifications would be without results if it wasn't for the tuning. Mena is a skilled engine tuner, and put his skills to use with the HP Tuners program. The HP Tuners program lets the engine tuner perform live diagnostic checks and on- the-fly tuning as the engine is running. Once the tune is perfected and adjusted, the OE computer is reflashed and ready to run.

After waiting for a few hours for the delivery of the new injector clips, the harness was wired up in about 30 minutes and the engine was now ready for start-up and tuning.

I have to sing the praises of the guys at Westech. They are not personally satisfied until they are certain they have given the engine the best map and tune. After about six pulls, the numbers peaked as far as they would go. Just to be sure, they ran a few more pulls afterward readjusting the fuel curve. Nope, the sixth pull was the best.

This graph and these numbers are from the first round of tests. Prior to the intake swap the peak horsepower is 441 at 6,200 rpm, while the peak torque is 410 at 5,200 rpm.

Now take a look at the numbers and graph after the intake and throttle body swap. The horsepower peak number is 475 at 6,400 rpm and stays that way until 6,800. The peak torque numbers are 413 at 5,300 rpm. One thing we noticed is that from about 2,500 until about 3,500 rpm, the torque numbers are anywhere from 14-16 lbs-ft less on the test with the new intake when compared to the OE intake. But from 3,500 rpm on, the numbers quickly catch up and even surpass the older number by a couple of lb-ft. While it may seem we sacrificed some low-end torque, we gained it back in the mid- to high-rpm range. However, the horsepower gains are undeniably cool. This intake smashed the horsepower numbers of the old tests.