Holley has developed a new range of Hi-Ram products designed for Chevy small-block engines that enables many more builders, restorers, and enthusiasts to enjoy maximum performance and awesome aesthetics from a big-capacity motor with a standard deck height. The new line joins existing Holley Hi-Ram offerings that cater for customers with Chevrolet LS and LT, Ford Coyote, 302 and 351 Windsor, and Gen III Hemi motors.
“Customers are already modernizing their small-block engines with EFI,” says Jim Dralle, engineering manager for Holley’s Classic Muscle division. “We want to take the same engine platform approach that we have for the LS and Windsor and apply that to the classic Chevrolet motors.”
Hi-Ram intake manifolds for classic small-block applications are now available as an ideal complement to an EFI conversion. Cast-aluminum construction makes them a cost-effective alternative to billet or fabricated sheet-metal intakes and opens up options for custom porting, forced induction and other modifications. All manifolds come with Holley EFI fuel rails.
Two options are available. Part number 300-950 is a Hi-Ram top-feed manifold with a plenum volume of 526 cu.in., while the lower front-feed version (300-951) has a plenum of 364 cu.in.
Hood modifications may be required to accommodate the top-feed Hi-Ram manifold, but the front-feed option has been designed and tested to ensure fitment under the stock hoods of F-Body Gen 1, 2, and 3 Camaros, thanks in part to the care taken with the throttle-body adapter. Holley engineers were able to draw on experience from its Lo-Ram LS manifold designs in this area. Both small-block options also include a throttle-cable bracket and are set up to be paired with an LS-style throttle body: up to 105mm for 300-950 and 95mm for 300-951.
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The front-feed 300-951 Hi-Ram manifold also serves as a modern replacement for the aging Stealth Ram manifold, which is actually an older design derived from a Weiand Tunnel Ram. A modular approach means the new front-feed manifold shares its lower casting with its 950 Hi-Ram sibling, incorporating 6.35-inch-long runners with passages that are designed to match the ports of common, high-performance heads – or can be easily ported to fit others.
Clever packaging with the distributor is another feature of both new small block intake manifold variants. Despite the challenge of the limited space, Holley felt it was important to be able to retain a distributor to enable as many builders as possible to apply the Hi-Ram to their engine. “It’s tight, but we are very happy with the result,” Dralle enthuses. “You do however have to use an original-type, smaller-cap distributor like the MSD 85551, rather than something like an HEI.”
His engineering team relied on its skill and experience to create manifold designs with the desired characteristics, but it was crucial to thoroughly test the new products to ensure that they meet the designers’ goals. All-in, the development and test process took more than a year to complete.
“We run an engine with high-performance heads on the dyno to check we have no performance issues,” he explains. “Fuel injection keeps your fuel distribution good, but you must make sure the air distribution is where you want it, that the plenum works as it should. We monitor the air-fuel ratio in every cylinder throughout the dyno pulls.
“These manifolds get used on an amazingly wide range of engines, which makes it impossible to dyno test them on every type of motor,” Dralle continues. “But from our tests we can be sure that the manifold is performing well and doesn’t have any bad air-distribution characteristics. With an optimized camshaft, the Hi-Ram will make peak power anywhere from 7,000 and 8,000 rpm, depending on the displacement of the engine. People love the way they run upstairs, even if they’re not getting up into the higher RPMs. And of course, customers love the way the manifolds look!”
To begin with, the new Hi-Ram intake manifolds will be sold separately to the existing EFI products. In time, Holley intends to bundle the manifolds in a kit with EFI as a complete package for small-block upgrades.
“With our platform approach, we want to simplify the upgrade process as much as possible for our customers,” sums up Dralle. “For the owner who doesn’t want to transplant an LS, we are still able to offer a lot of the benefits of EFI while enabling them to retain their favored small-block Chevy power.”
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