LS3 Intake Shootout!
We Dyno-Test 19 Manifolds So You Don’t Have To
hWay back in 2015, we performed the mother of all LS intake tests by running 20 different intakes designed for cathedral-port heads. That test included every cathedral-port intake we could get our hands on, including the various factory versions. The problem with doing the mother of all intake tests for the cathedral-port guys is that it left out the LS3 owners. GM eventually replaced the cathedral-port heads with high-flow, rectangular-port heads when it introduced the LS3, L92, and L76 motors (to name a few). Blessed with what were essentially race heads right from the factory (flowing 315 cfm), the rec-port motors offered even more potential than the factory cathedral-port combos. Not surprisingly, the aftermarket jumped on the bandwagon to offer all manner of intake combinations for the new cylinder-head configuration, so it was only natural that we had to test them. Unlike the previous adventure, we decided to split up the EFI and carbureted intakes and test them separately. Provided here for your viewing pleasure are the results of part 1 on the EFI intakes.
Before getting to the results, we need to point out a few facts, the first of which is that the factory LS3 intake is one of the best OE intakes ever produced. Unlike the previous cathedral-port examples, even the mighty Trailblazer SS (TBSS) manifold, the stock LS3 intake, has proved tough to beat. Oh sure, it’s possible to shift power production higher in the rev range with shorter runners, but this usually comes with a trade-off in low-speed torque—sometimes a significant one. This is an important point, as many of these intakes were not designed for our mild cam-only LS3 crate motor—specs on our COMP 54-496-11 hydraulic roller measure 231/247 degrees at 0.050 and 0.617/0.624-inch lift with a 113 lobe-separation angle (LSA)—and would be better suited to something with wilder cam timing, more displacement, or both. Intakes should be thought of in terms of engine speed (much like a cam). The runner length (and other design variables) determines the effective operating range. Match this range with the right cam timing, head flow, and displacement, and you have a winning combination.
The internet will be quick to grab the peak numbers from this test and run with them, but there is much more to an intake, or the power curve it produces, than simple peak values. A review of the data will reveal that the difference between the least and most powerful intakes was more than 65 hp. This is a significant chunk of change, but peaks only tell part of the story, as acceleration is a function of average power production. Understanding this, we included average power production from 3,100 to 7,000 rpm. We also included torque production at 4,000 rpm, because street driving entails much more time in this part of the power curve than at maximum rpm. The point here is that all of the data is important, and if you’re looking for the very best manifold ever made, you are looking in the wrong place. No such animal exists, so don’t be disappointed. If, on the other hand, you’re looking for data to select the best intake for your application, sit back and enjoy.