Intake Manifolds

Choosing the right intake manifold for your V8 build

The intake manifold is one of the few components where a single swap can meaningfully shift where the engine makes its power, without touching the heads, the cam, or the short block. Dual plane and single plane intake manifolds produce measurably different torque curves on identical engines. On an LS engine swap, fitting the right EFI manifold architecture can be the difference between a build that drives well on the road and one that idles poorly and frustrates on the commute.

The decision is straightforward once you know the three things that matter: what design type suits your RPM target, which manifold fits your engine family, and whether you're running a carburettor, traditional EFI, or a modern throttle body setup.

What to look for

Design type: dual plane, single plane, or EFI-specific

Manifold design governs where in the RPM range the engine produces its best cylinder filling. A dual plane manifold uses a divided plenum with longer, separated runners. The longer runner path builds intake charge velocity at low and mid RPM, which translates to strong torque from idle through to around 5,500 RPM. For a street-driven car, a restomod, or anything that spends time at partial throttle in traffic, dual plane is the correct architecture.

A single plane manifold uses an open, undivided plenum with shorter runners. The open plenum allows the engine to breathe freely at high RPM but reduces charge velocity at low RPM. The torque curve shifts up the rev range. For a track day car, a dedicated drag build, or an engine that will spend its working life above 4,000 RPM, single plane gives back what it takes away.

EFI-specific manifolds, particularly the Holley Hi-Ram and Lo-Ram designs, are purpose-built for fuel-injected applications and allow configurations that carburettor manifolds cannot accommodate: individual throttle bodies, dual throttle body setups, blower-hat arrangements, and high-mount plenum designs that clear tight engine bays on LS and Coyote engine swaps.

Engine family and port fitment

An intake manifold is machined to match the intake port geometry of a specific cylinder head. Cathedral port, rectangular port, and D-port LS heads are not interchangeable. Small-block Chevrolet and small-block Ford manifolds share nothing. Coyote manifolds are specific to generation (pre-2015, 2015-2020 GT350, 2019-2022 Bullitt variants differ in throttle body attachment and port geometry).

Before selecting a manifold, confirm the cylinder head port style on your engine. For LS builds this typically means identifying whether you have Gen III cathedral port heads (LS1, LS2, LS6) or Gen IV rectangular port heads (LS3, L92, LS7). The manifold note and the engine family it lists are the authoritative check, not the engine code alone.

Fuel delivery architecture

Carburetted builds use manifolds designed to mount a four-barrel carburettor on a square-bore or spread-bore flange. Traditional EFI builds use manifolds with injector bungs and a throttle body mounting pad, often similar in external geometry to a carburetted manifold but ported and machined for injector bosses. Modern EFI manifolds for LS and Coyote applications, such as the Holley Lo-Ram and Hi-Ram range, go further: they are designed around the EFI system's fuel rail architecture, plenum volume, and throttle body count from the outset, rather than being adapted from a carburettor design.

If you are running a Holley Sniper, Terminator X, or similar self-learning EFI on a small-block Ford or traditional V8, a conventional EFI manifold or even a quality carburettor manifold with throttle body adaptor will work. If you are building an LS or Coyote swap with a purpose-built EFI management system, the Hi-Ram or Lo-Ram architecture gives you the flexibility to configure the induction system correctly from the start.

Where the criteria pull against each other

Street drivability and peak power point in opposite directions. A dual plane manifold gives you the torque and idle quality a street car needs, but it limits top-end breathing. A single plane gives you peak power but makes a street car feel flat below 3,500 RPM.

Hi-Ram manifolds offer maximum plenum volume and throttle body flexibility but add significant height. On a classic car chassis with a tight bonnet line, a Lo-Ram design will clear the bonnet where a Hi-Ram will not. The Lo-Ram trades some peak flow for packaging. On most UK street builds the Lo-Ram is the more practical choice; on dedicated power builds where bonnet clearance is not a constraint, Hi-Ram is the better architecture.

Installation complexity also varies. EFI manifolds that require individual throttle bodies or custom fuel rails take more time and more ancillaries than a single-carburettor dual plane on the same engine. Budget both the parts cost and the build time when comparing options.

Which manifold to pick

Street-driven carburetted V8 (small-block Chevy, small-block Ford, LS with carb conversion): start with a dual plane. The broader torque curve suits road driving. A single plane is the wrong choice unless the car will rarely see traffic.

Naturally aspirated track build or dedicated drag car: single plane, matched to the head port style and the intended RPM ceiling. Confirm runner length against the engine's target power band.

LS engine swap with EFI management (LS1/LS2/LS6 cathedral port): the Holley Lo-Ram range is the practical starting point. It suits both street and mild track use, supports standard and dual throttle body configurations, and clears most engine bays.

LS3 or L92 rectangular port build with higher power targets: the Ultra Lo-Ram design suits engines making more power and operating higher in the RPM range, where the optimised runner geometry earns its keep.

Coyote engine swap, 2015-2020 GT350 or 2019-2022 Bullitt generation: the Holley Ultra Lo-Ram for those specific build years retains OEM throttle body fitment while enabling modern EFI management. It is the most straightforward path to a running Coyote swap without fabricating a custom throttle body mount.

Top picks for LS and Coyote intake manifolds

Holley Lo-Ram Manifold Kit Single Injector, LS3/L92 is the go-to choice for LS3 and L92-headed builds running a single throttle body EFI setup. The Lo-Ram profile keeps overall height in check, which matters on any swap where the bonnet line is a concern. It supports standard EFI management systems including Holley and non-Holley ECUs when used with the appropriate sensor provisions. A solid choice for a street build that may occasionally see track days.

Holley Ultra Lo-Ram Manifold Kit Single Injector, LS3/L92 steps up the runner and plenum geometry for builds where the engine will operate at higher RPM and needs greater top-end flow. It uses the same low-profile architecture as the standard Lo-Ram but with runner geometry optimised for higher-output naturally aspirated or mild forced induction builds. The right choice when the LS3 or L92 engine is built past stock power levels.

Holley EFI Ultra Lo-Ram Ford Coyote, 2015-2020 GT350 and 2019-2022 is the correct manifold for Coyote swaps based on the GT350 generation engine or the 2019-2022 Bullitt-spec engine. OEM throttle body fitment means no adaptor plates or custom fabrication at that junction. For a restomod or a classic American iron project built around a Coyote donor, it removes one of the more awkward fitment questions from the build.

Holley Hi-Ram Lower Manifold, LS1/LS2/LS6 serves the cathedral port LS family (LS1, LS2, LS6) and suits both carburetted and EFI applications where maximum plenum volume is needed. The Hi-Ram architecture gives more room for high-flow throttle body configurations and suits builds where bonnet clearance is not a limiting factor. It is also the right choice for an LS-based engine that will eventually run boost, where plenum volume becomes more relevant.

For engine management to run any of these EFI manifolds correctly, see the Holley EFI collection.