Holley's Lo-Ram EFI Intake Manifolds Offer ultimate Versatility

10 min read

Holley's Lo-Ram EFI Intake Manifolds Offer ultimate Versatility

10 min read

With several different configurations and displacements manufactured since its inception in 1997 the LS engine family has become the clear choice for engine swappers and enthusiasts worldwide. So many engines are sitting in scrapyards waiting to be rescued and make the perfect base for solid, high-performance builds that the aftermarket has taken to the platform in a way like no other engine since the original small-block Chevrolet. Holley's LS1/2/6 (cathedral port) and LS3 (rectangular port) Lo-Ram and Ultra Lo-Ram intake manifold kits offer many finishing options for these enthusiasts. The kits come together to be a versatile manifold option for nearly any application, no matter which cylinder head configuration is atop an LS-based engine. There are more than 45 part numbers related to the Holley EFI LS Lo-Ram intake systems and they are one of the most compact on the market when under-hood real estate is at a minimum.

Holley Senior Design Engineer Jim Dralle started this project with a clean slate; after observing and noting the shortcomings of other offerings on the market, along with a long list of potential features to incorporate into this new design.

Holley 300-679BK

The extremely low profile of the Front Feed Ultra Lo-Ram offers a ton of clearance and even allows this intake to fit under the hood of cars like the 4th-Gen Camaro and C5 Corvette, which are notable concerning lack of underhood clearance. Note that the injector boss area offers room for two injectors even if the intake uses the single-injector option. Whether the end-user takes advantage of this flexibility is their choice; Holley provides the capability to add the second injector, or perhaps nitrous or water/methanol injection, to each cylinder in every Lo-Ram manifold base.

“We figured a lot of people were taking 5.3s and doing forced induction with them, so we picked the cathedral port first only because of the 5.3. But from the very beginning, we intended to do the LS3 as well,” says Dralle.

The Holley EFI Lo-Ram intake manifolds provide the end-user with an immense amount of flexibility and growth potential. As the enthusiast’s needs change, they can adapt the manifold to work with their new goals and incur a minimum of difficulty when purchasing different pieces to adapt to those needs.

Because the basic layout of the intake manifold is the same across platforms, Holley created several parts used on cathedral-port and rectangular-port intakes alike; the modular concept is how the intake can grow with the owner’s needs.

Lo-Ram double injector boss

For those racers using the dual-injector option, Holley has designed a set of bolt-on dual-feed billet fuel rails to secure both injectors easily and securely.

“It uses the same single and dual rails, it shares the same plenum top for both the top-feed and front-feed. It’s very similar to the modularity of the High-Ram; we pulled from those cues to make this so people could do a myriad of things — whatever their ideas lead them to do. For example, you could make different plenum tops or throttle body adapters if you don’t like the standard ones we offer,” says Dralle.

Lo-Ram intakes can be used with either stock or aftermarket cylinder heads. The ports also have ample material to be enlarged or port matched.

Great For Boost

From the outset, Holley designed the Lo-Ram intake manifolds to be an excellent choice for the thousands of boosted LS engines on the planet. Using a turbocharger or supercharger in front of the LS platform is the winning formula for many enthusiasts, and Holley EFI optimized this intake for those users. Regardless of whether the user needs a cathedral-port or rectangular-port intake, the bottom portion of the intake manifold uses short runners and has an extremely low profile.

Because of the low profile, it’s much easier for the end-user to fit an air-to-water intercooler between the lower and upper halves of the Lo-Ram design.

“We wanted to build something low so that you could put a water-to-air intercooler sandwiched in the plenum. The idea was to do a lower one for those applications knowing they’re for forced induction engines. Runner length wasn’t an issue because you don’t need to build the torque via intake tuning. Then, once we started designing it, we thought we could make it a front feed from the same casting. A lot of people like that because of the way it packages,” says Dralle.

Holley 300-600BK

With several manufacturers already building air-to-water intercoolers that work with Holley’s Hi-Ram intake manifold design, Holley engineers realized designing the Top-Feed Lo-Ram intake with the exact lid dimensions would make it easy to retrofit those existing designs to the intake and also use any of the available Hi-Ram plenum tops. Internally, the intake base has cast-in smooth inlets for each port to guide the incoming air into the cylinder head. Holley designed these to minimize turbulence, straighten out the incoming air, and provide a strong signal to the plenum.

Since the top-feed unit uses the Hi-Ram plenum top, and water-to-air intercooler setups already exist for that platform, the use of the standard plenum flange in the Lo-Ram makes it easy for the end-user to adapt one of those setups to the top-feed Lo-Ram — and any of the Hi-Ram lids work, according to Dralle. He says that a user could install a side-entry Ford Hi-Ram lid, or the top-entry style carburetor lid would work with a throttle-body style fuel injection system. The front feed Ultra Lo-Ram will even fit under the hood of a C5 Corvette or 4th-Gen Camaro – cars not known for massive hood clearance.

These intakes will make peak power between 7,000—8,000 rpm depending upon engine parameters, which puts them right in the sweet spot for performance when sucking down forced induction from a well-built LS.

Other Considerations

With the plenum side of the equation figured out, Holley turned its attention to what we’ll call the ancillary parts of the design. Casting the lower intake with plenty of meat around the injector area meant that Holley could outfit these intakes with the option for a second set of fuel injectors for those enthusiasts pushing the absolute limits. Single or dual fuel rail intakes are available. Injector locations are mapped out for a pair of injectors regardless of which lower intake is purchased; if the buyer chooses the single, they can always take the lower manifold and have the injector holes drilled later their combination grows to that level. In addition, fuel rail kits come with two sets of brackets — one for long injectors and one for short injectors — so the user can select the injectors that work correctly for their engine program and not have to hunt down parts on assembly day.

Holley EFI’s 105mm, LS-style throttle body is a direct bolt-on for any Lo-Ram intake manifold configuration. The lower manifolds and tops are available individually so the customer can mix and match, and pieces are available in cast silver and satin powder-coated black finishes. Also important to note are the Front Feed lids with available SFI-spec burst panels and billet aluminum exit ducts that have become familiar to high-powered combinations, designed to prevent hood damage in the event of an over-boost situation.

Lo-Ram 105mm throttle body

With an opening that will accept Holley’s 105mm EFI throttle body (or similar), the Holley EFI Lo-Ram intake designs give LS owners what they need to make big, boosted power.

The castings are nicely contoured to remove unnecessary weight where it’s not needed and utilize now-familiar rubber gasket solutions around the ports and lid openings to maximize sealing capability and serviceability.

“These give you a lot of options; even with the dual rails, you could be running on gasoline on the primary injectors and E85 or race fuel on the second fuel system. This design competes with billet stuff. It’s a cast manifold system with similar features to some of the $3,000 billet kits out there. That’s what we tried to do — create as much flexibility for the customer as possible so they can use their imagination to do what they want to do,” sums up Dralle.


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