General Motors’ 4th Gen F-body was a radical design. With its steeply raked windshield and bird-beak nose, the ground-breaking LS1 powerplant was tucked halfway under the cowl. But with the LS1’s factory intake manifold nestled neatly in the valley of the Gen III V-8, cowl clearance isn’t a problem. Intake manifold options, however, are severely limited to low-profile designs. Those with high-horsepower engines had two choices, the first is to use the stock or aftermarket low-profile plastic intake manifolds, or cut the stock cowl, lose the windshield wipers, and possibly even cut the windshield!
Fortunately, Holley has a new option with its Modular Lo-Ram EFI intake manifold for LS1, LS2, and LS6 engines. Its large, short runners are great for making big top-end power and its large plenum complements supercharged and turbocharged applications, unleashing the full potential from your cathedral-port LS engine.
This intake is designed to flow some serious air. The Holley Lo-Ram EFI intake manifold (P/N 300-621) accepts Holley’s monstrous 105mm throttle body (P/N 112-581), while the front-feed design is a direct replacement for factory-style intakes. The best part is that its overall height is the same as that of a factory LS1 manifold.
The cast aluminum construction of the Holley Lo-Ram EFI intake manifold is also perfect for high-boost applications, simply because plastic manifolds puff up like a balloon in these applications. There are even bosses for additional fuel injectors or nitrous nozzles. Holley even includes a new set of fuel rails and two sets of mounting brackets: a set for long (usually standard length) fuel injectors and a set for short (such as Pico, or LS7) fuel injectors.
To sample the benefits of the Holley Lo-Ram intake manifold, we went over to Boost Addicts in Gallatin, Tennessee to install one on a customer’s twin-turbocharged 1998 Camaro. Shoving 19 PSI of boost through a stock plastic LS1 manifold, this Camaro was the perfect candidate to show what the Holley Lo-Ram could do.
Here’s our test subject: a 1998 Camaro with a 370-cube LS1 fed by two turbochargers. The engine made 797 horsepower on 19 PSI of boost with the stock LS1 plastic manifold. The folks at Boost Addicts noted that the manifold would “swell” under full boost!
Here’s the problem. The low cowl on 1993-2002 GM F-bodies eliminates most aftermarket “ram” style intake manifolds–unless you want to cut the cowl, lose the windshield wiper mechanism, and cut the windshield.
The modular design of the Holley Lo-Ram EFI intake manifold (P/N 300-621) utilizes a front-feed throttle body inlet and a removable cover.
The back of the Lo-Ram intake is plumbed for vacuum fittings and a MAP sensor and the short, wide runners are designed to maximize top-end power and mate to cathedral-port heads.
After we were done ogling the Holley Lo-Ram, we removed the stock plastic LS1 intake from the engine.
We started assembling the Holley Lo-Ram intake by laying the supplied gasket in the top cover O-ring groove. With the cover in place, we installed and torqued the 12-point bolts and used a razor blade to trim off the excess gasket until it was flush.
We tipped the manifold upside down on a work bench and installed the included port flange seals flange seals.
Next, we turned our attention to the front throttle body adapter and routed the shorter rope gasket into the groove and marked where the two ends overlapped. We used a razor blade to cut the rope gasket to the appropriate length and joined the two ends with Cyanoacrylate (A.K.A “super glue”). With the rope gasket in place, we installed the throttle body adapter bolts.
Here is a comparison between the Lo-Ram and the stock manifold. As you can see, the external dimensions are very close. This is what allows the Low-Ram to clear factory hood
We plumbed the ports at the back of the manifold for the brake booster, boost reference, and crankcase vent. Now, it was ready to be lowered onto the engine.
After using the included studs to fasten down the Lo-Ram intake manifold, we prepped and installed the included fuel rails. These are billet aluminum jewelry. Note that we used the supplied “long” fuel rail brackets to accommodate these “long-style” fuel injectors.
Like a glove! The Lo-Ram fit perfectly in place of the factory intake manifold.
With the Camaro back on the dyno at Boost Addicts, we were ready to make some pulls. Even with dramatically shorter runners than the stock manifold, the Holley Lo-Ram made more horsepower and torque across the power band. Peak gains were 44 horsepower and 26 lb-ft of torque with this turbocharged setup.
