These days, RHS keeps setting the Gen III/IV market ablaze with the recent launch of its LS Race Block and all-new Pro Elite LS7 cylinder heads. As the older generation of hot rodders will tell you, however, Racing Head Service has a storied history that goes way back. Founded in 1967, RHS quickly became one of the leaders in cylinder head port development with a tremendous amount of success in drag racing and circle track. As the company evolved into a complete engine supplier, it realized that there was a void in the industry for performance camshafts. Consequently, RHS created the COMP Cams division in 1976, and it was eventually split off into a separate entity. RHS went dormant in the '90s, but COMP Cams retained the rights to the RHS brand. When the time was right in the early '00s, RHS was revived as a member of the COMP Performance Group.
The resurrection of RHS coincides with the COMP Performance Group's acquisition of Pro Action cylinder heads. Recognized by both casual cruisers and hard-core drag racers alike as offering exceptional performance for the dollar, Pro Action developed a cult following in the marketplace. After becoming part of the COMP Performance Group, Pro Action was able to leverage its new engineering and manufacturing resources to expand its cylinder head line and take the company to the next level. Today, the RHS/Pro Action tandem is on top of their game, and the horsepower-hungry public are the beneficiaries. To learn all about the company's newest products and the cutting-edge technology that goes into developing them, we recently had an in-depth conversation with Kevin Feeney of RHS.
LS Race Block Development
RHS has been long known for its high-performance cylinder heads, but it shocked the hot rodding community with the launch of the LS Race Block. Recognizing an opportunity to give racers what they want, RHS decided to enter the aftermarket LS block market. "The LS platform has been growing by leaps and bounds over the last several years, and while the OE blocks are a very good piece for most naturally aspirated street applications, they are limited in maximum cubic inches due to their low deck height. Additionally, the trend toward boosted applications is growing, and engine builders are easily able to reach power levels that exceed the strength of the OE block," Feeney says. "The aftermarket had been reluctant to make an LS block due to the complexity of the design, but at RHS our engineers were confident that with the right foundry partner we could make significant improvements to the design. Our goals were pretty straightforward: Design a block robust enough to withstand the abuse of boosted applications, the ability to accommodate more cubic inches, and maintaining compatibility with Gen III and Gen IV small-block components and accessories while still fitting under the cowl of a stock Corvette and Camaro."
We strive to achieve a port design that provides an engine with a properly balanced port. The result is great horsepower that doesn't sacrifice torque and driveability.
Built for Power
The RHS LS Race Block has become very popular in max effort race motors. This is no coincidence, as several design elements incorporated into the casting maximize durability without a dramatic increase in weight. RHS engineers point out that the key to the block's strength is in its unique casting design. "We partnered with Grainger & Worrall—a top-notch foundry that uses the Cosworth foundry technique—due to their wealth of experience in high-horsepower, thin-section casting designs. The block has a lot of triangulation in the exterior design to strengthen the case," Feeney explains. "We also spent a tremendous amount of time on the design of the water jacket, and in maintaining equal wall thickness on the parent bore. This provides the most support possible around the pressed-in liner to maintain ring seal. We also chill the bulkheads and inner bore sections to provide the highest metallurgical properties possible. Though the exact power levels the RHS block can handle are not known, in boosted applications we have numerous customers putting 2,000-2,500 hp through them."
People who buy aftermarket blocks are typically seeking maximum displacement. With this in mind, RHS engineers have incorporated several features that make the LS Race Block very accommodating of large cubic-inch applications. "The first thing we did is increase the deck height to 9.750 inches, which is 0.500-inch taller than the OE design. This was the tallest we could go and still fit under the factory cowl of late-model applications," Feeney says. To make the block more accommodating of long-stroke crankshafts, RHS engineers raised the camshaft up in the block and designed a priority main oiling system that relocates the main oil galley outboard. This allows for a stroke as long as 4.600 inches to easily swing inside the crankcase with a standard 2.100-inch rod pin. "We also maximized the cylinder liner length to provide the best possible piston skirt support. Between the added deck height and longer stroke, the block is capable of 502 ci. We also added many features, such as the capability of running piston oilers, Gen I small-block motor mount boltholes, and a motor plate bolt feature for all-out race applications."
RHS goes to great lengths to ensure stringent quality control in each LS Race Block that it ships. In fact, each block undergoes a CT scan during the manufacturing process. "The benefit of performing a CT scan is that it lets us know exactly what the wall thicknesses are after the part is made," Feeney says. "This information allows us to target the machining of the casting to maximize the wall thickness of the machined part in all of the critical areas, particularly in the cylinder bores. Not only does this maintain even wall thickness, it also promotes maximum ring seal."