Description
Holley LS Cathedral Port Hi-Ram Modular EFI Intake Manifold Kit
Engineered for high-RPM and forced-induction GM LS applications with cathedral port heads.
Product Overview
The Holley 300-123 Modular Hi-Ram EFI Intake Manifold is a premium performance induction kit designed as a high-flowing alternative to fabricated sheet-metal intake manifolds. Specifically engineered for GM LS1, LS2, and LS6 cathedral port cylinder heads, this high-ram runner design optimizes airflow velocity and plenum volume for high-horsepower naturally aspirated and boosted race engines. Complete with a 105mm 4-bolt throttle body plenum top and high-capacity billet fuel rails, it is the ultimate intake choice for drag racing, circuit track cars, and high-performance street machines.
Key Features
- ☑ Cathedral Port Fitment: Tailored for GM LS1, LS2, LS6, and 4.8L/5.3L/6.0L cathedral-port cylinder heads.
- ☑ 105mm Throttle Body Flange: Includes longitudinal plenum top engineered for 105mm 4-bolt LS throttle bodies.
- ☑ Billet Fuel Rails Included: Comes standard with high-flow billet EFI fuel rails with -8 AN O-ring female ports.
- ☑ High-RPM Power Band: Runner length and tapered cross-section tuned for peak output between 7,000 and 8,000+ RPM.
- ☑ Modular Cast Aluminum: Durable natural cast aluminum construction allows modular top swaps for custom setups.
Technical Specifications
| Brand | Holley |
|---|---|
| Manufacturer Part Number | 300-123 |
| Engine Compatibility | GM LS1 / LS2 / LS6 & Cathedral Port Blocks (4.8L, 5.3L, 6.0L) |
| Cylinder Head Style | Cathedral Port |
| Throttle Body Opening | 105mm (4-Bolt LS Pattern) |
| Plenum Base Height | 8.42″ (from valley cover flange to top) |
| Material / Finish | Cast Aluminum / Natural |
| Fuel Rail Fittings | -8 AN O-Ring Female |
| RPM Operating Range | 7,000 – 8,000+ RPM |
What’s Included in the Box
- Holley Hi-Ram Cast Aluminum Base Manifold
- 105mm Modular Plenum Top (Natural Finish)
- High-Flow Billet Fuel Rail Set (-8 AN Ports)
- Plenum O-Ring Gaskets & Mounting Hardware
- Intake Manifold Runner Port Seals
When building a serious high-revving or forced-induction LS engine, Holley EFI manifolds deliver race-proven induction efficiency. As an official UK distributor, JP Racing provides genuine Holley components backed by fast UK dispatch and technical customer support.
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