![]() ![]() However, the Atomic Air Force will also fit under stock hoods. Finally, while not necessarily a performance parameter, the Atomic Air Force manifold is the only polymer intake on the list. Next is the fact that the runners on the Atomic Air Force are much longer than those of the Hi-Ram. ![]() First, the Air Force manifold tested hasn’t been ported at all, so that puts it at a distinct disadvantage. If you were to look up “apples and oranges,” the Atomic Air Force intake being included in this test would probably pop up. “The better the alignment, the better it is over the port, the more opportunity is there for better cylinder filling. In Brule’s mind, there’s almost no doubt that the straight shot provided by the dual quads adds to the equation compared the rotation of the air required by the forward-facing intake. Gearhart points out that the 105mm throttle body is rated at about 1,500cfm, so about 25-percent less than the dual 4150 throttle bodies, and about 50-percent more than a single 4150 throttle body. I’d choose the dual 4150 setup if it were a street car, but I might choose the 4500s for a drag car, because they look so cool.” It just has the potential to make the engine touchy. “The throttle size isn’t going to change the way the engine accelerates a whole lot. “It’s interesting when we start talking about acceleration rates of the engine, and how you need airspeed to make the carburetor work, the fuel injection isn’t going to be as sensitive to that,” Brule explains. “That proves the fact that we don’t really need as much airflow as the 4500s could deliver,” says Gearhart. If you look at the curve, it is almost a trace of the 4500 curve, with a slight separation on the bottom and top ends. The dual 4150 setup netter 747.7 horsepower and 621.1 lb-ft of torque. The smaller dual 4150 throttle bodies are rated at half the airflow of the 4500s (1,000cfm vs 2,000cfm) but still performed quite well in this test. That’s going to make it pretty touchy to drive,” Brule concludes of the dual 4500 configuration. ![]() If you were to try and drive this combination on the street, there is a lot of surface area that is available and opens all at once. “In a drag race application, this is fine. So I think the results we saw, where there is a slight divergence in the curve over the 4150s might be as much related to bore-spacing with the bores being a little better aligned over the ports.” “There’s about three or four times that much on here right now. “The math says this combination is supposed to use about 1,000 cfm of intake flow,” explains Brule. The combination topped the charts, making 754 horsepower and 624 lb-ft of torque. Each of the 4500 throttle bodies is rated at 2,000 cfm for a whopping 4,000 cfm of airflow available. He says “obviously” because this is the combination with the most intake flow. “ was obviously the winner,” says Gearhart. However, it will still decently illustrate the differences between the different models of manifolds. One thing to keep in mind with the absolute numbers presented on this dyno graph is that this engine is a pretty stout combination. Besides making a convenient test methodology, it also shows the versatility of Holley’s Hi-Ram intake manifolds. The particular lower intake manifold used in the test has been ported to match the cylinder heads by Brett Barber of Air Flow Solutions. Now just to be clear, three of the four intakes tested all use the same Hi-Ram lower intake. With Holley’s Mark Gearhart and Westech’s Steve Brule analyzing the results, it comes down to way more than just peak power numbers, as they point out. So, using a 440 cubic-inch LS engine (we covered the short-block build here, and we’ll have the long-block article up soon), Holley went to Westech Performance Group to test out four of the most popular LS intake manifolds they make. With Holley Performance leading the way and creating a plethora of intake manifold options for the platform, the team realized that with all the different options now available, it could be confusing as to how each different iteration performs. Whether you are a fan of the Bowtie or not, there is no denying that the LS platform has some of the strongest aftermarket support of any platform, ever. ![]()
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