The fact that nostalgia is big business has not been lost on the marketing team at Chevrolet. One need only look at their most recent ZL1, ZR1 and (the focus of this story) LS7 to see that they are not above playing off the success of performance past to sell future fast. Unlike the two supercharged applications, the all-motor LS7 was much more in tune with its namesake. We applaud the fact that Chevy saw fit to make the modern versions follow this tradition of performance.
In the case of the new LS7, Chevy knew that enthusiasts wouldn't accept the moniker applied as a sticker package to some pedestrian-pushing poser. After all, the original LS7 was a high-compression, solid lifter 454 originally slated for use in the '70 Corvette (essentially a 454 cube version of the L88 of 1967-'69). Prior to production, the wild LS7 combination was cancelled, but was later offered as a successful crate motor through Chevy dealers. Though the LS7 never saw use in a production vehicle, its popularity as a performance swap engine more than justifies its legendary status.
The modern LS7 certainly carries the torch, offering performance the old fashion way, through cubes and compression. Though not quite as high as the original, the 11.0:1 compression offered by the modern LS7 is right up there with the best of the factory muscle car motors. Down on displacement slightly to the original 454, it is important to remember that the 427.5 ci offered today comes in a small-block package. Not just physically smaller, the modern LS7 also offers all-aluminum construction, a composite intake and electronic fuel injection.
The modern LS7 delivers not just more power than its big-block brethren, but does so while delivering four times the fuel mileage and far fewer harmful exhaust emissions. Time and technology have indeed marched on, but it is nice to know that the current configuration is true to the performance of the original.
As impressive as a modern LS7 is, there are always ways to make it even better. The key to performance on any engine is airflow. Increase the airflow through the motor and you will be rewarded with more power. Notice we said airflow through the motor and not just to the motor. Unfortunately, the internal combustion engine doesn't recognize potential airflow. The mere fact that a larger throttle body, intake manifold or even cylinder heads flow more air doesn't necessarily translate to increased power.
The entire LS family of small-blocks was treated to high-flow cylinder heads, but none more than the LS7. With enough flow from the stock head to easily feed the 505hp 427, adding ported heads to an otherwise stock motor will yield predictable results. Having 600hp heads on a 500hp motor means adding a set of 650-700hp heads might not offer much in the way of additional power, since the combination already has enough head flow to support the current power level. That is why our test of the new Brodix STS BR 7 273 heads was run on something capable of utilizing the extra airflow.
The new STS BR7 273 heads from Brodix offer a unique combination that all but guaranteed success. It is true that airflow equates to power, but there is more to the equation than big numbers. Getting big flow from big ports is easy, but doing so with reasonably sized ports is the key to a successful head design. Factory LS7 heads offer plenty of flow (exceeding 335 cfm), but do so with sizable intake port volumes (270-plus cc). Getting even more flow from a production casting means making the port even bigger. As long as the flow rate goes up in proportion to the increase in port volume, power production is assured.