New FAST LSXR Intake Manifold & RHS LS Race Block - Expanding Horizons

Comp Performance Group Raises The High-Performance Bar With A New Fast LSXR Intake Manifold And RHS LS Race Block

Chris Werner Apr 1, 2009 0 Comment(s)

The folks at COMP Performance Group have been hard at work on a selection of products sure to be an instant grand slam with the LS community, and two particularly interesting items on hand at the shows were a new FAST intake manifold and (introduced at PRI) a new RHS engine block.

Missed both Vegas and Orlando in `08? Brian Reese, Director of Engineering and Business Development at COMP Performance Group, hooked us up with some cutting-edge information on these new products, so read on to find out what everyone's been talking about.

Fast LSXR 102mm Intake ManifoldGMHTP readers are surely well versed on the original FAST LSX intake manifold. Available in both 78mm and 90mm configurations, it took the LS world by storm years back, providing thousands of enthusiasts with bolt-on performance increases for engines mild to wild. In test after test, we've shown these intakes to be proven performers, and the more recent 92mm manifold only upped the ante. But since these manifolds were designed for use with the original cathedral-port heads first seen on the LS1, the company has until now left owners of rectangular-port LS engines out in the cold.

Well, times they are a changin', because FAST has just unveiled its LSXR 102mm Intake Manifold, a piece that delivers increased flow capabilities for rectangular-port (LS3/L92-style) engines. So what makes the LSXR special? Some highlights on this new manifold and details of its development will clue you in.

Design Process
An appreciation of the glory that is the LSXR is impossible without at least a cursory understanding of the engineering that went into it. The science of air flow as applied to internal combustion engines is quite complex, but pretty much everyone already knows that more air enables more power; getting an engine to ingest additional air is the key to increased output. As applied to the intake manifold, the main factors that dictate engine air flow are fourfold: (1) "command," comprising throttle and valve opening events; (2) pressure differential, which can be referred to as "potential;" (3) "obstacles," consisting of flow path and restrictions; and (4) wave tuning, which is a part of potential/momentum. Design of a well-performing intake manifold comes down to proper application of this science and all of its intricacies.

That said, in order to develop the LSXR, Reese and other FAST engineers coupled computer-aided design techniques with dyno testing, and the process began with a thorough evaluation of factory manifolds to determine a baseline to build from. This included dynoing, precise physical measurements, flow testing, and building of computer models that would accurately represent the stock manifolds in digital form. With mountains of data on the factory items now in hand, Computational Fluid Dynamics (CFD) was utilized in order to model air flow through virtual manifolds, thereby creating a "virtual flow bench" for use in the LSXR's development. Among the aspects of air flow looked at and data generated in this process were velocity and pressure diagrams, flow initiation and paths, and evaluations of energy loss. The models proved crucial in the design of the intricate shape of the interior of the manifold, particularly the precise contours of the runners. Important flow considerations included requirements of turning the air (air is lazy and doesn't like to change direction), flow separation concerns, distribution in the plenum, and upstream/downstream considerations. Just as important were tuning considerations, which included: wave tuning (i.e., constructive use of the reflective pressure waves resulting from opening/closing events of the intake valves to give added pressure differential over natural aspiration, forcing additional air into the cylinders); inlet shape and orientation; runner length, taper, area, and shape; plenum volume; and engine variations. Packaging limitations played a role in both.

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