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Holley 300-237 Hi-Ram Lower Manifold, GM LT1
Holley 300-237 Hi-Ram Lower Manifold, GM LT1

Holley 300-237 Hi-Ram Lower Manifold, GM LT1

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Holley 300-237 Hi-Ram Lower Manifold, GM LT1
Holley 300-237 Hi-Ram Lower Manifold, GM LT1
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We estimate this item will ship on or before April 6th.
Part # 425300237
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Important Messages:

  • This item ships directly from the manufacturer. It may take an additional 10 business days for Holley to ship this item.
  • Get FREE shipping when your order includes this item and exceeds $99! Ground shipping only in the contiguous US.
  • This item ships via Ground Shipping only. Expedited and Air shipping options are not available.


Intake Manifold Type:
Tunnel Ram
RPM Range:
Material Type:
Intake Section Included:
Base Only
Overall Height:
MFG. Part #:
Sold in Quantity:
GTIN Code:


The new Holley EFI Hi-Ram intake provides the ultimate performance with the new GM direct injected Gen V 6.2L LT1 engine. The modular design of this manifold allows easy disassembly for custom porting, multiple tops, or custom induction systems. Each runner has a large radius where it meets the plenum, and optimized taper & cross-sectional area to perform in a wide variety of engine configurations. The optional injector bosses on the intake runners allow increased performance potential by using additional injectors along with the factory direct injection. When you look for the pinnacle of performance, price, and quality, look to Holley EFI.

LT1 Hi-Ram, Lower Manifold Only w/out Port EFI Provisions. Order Plenum Top Separately.

  • Modular Design w/ Removable Top
  • Overall Height: 13.34” (w/ EFI Top - 95mm or 105mm) – See Drawing
  • A-B Height: 12.10” (w/ Carb Style Top - 2 x 4150 or 2 x 4500) – See Drawing
  • Height at Plenum Flange: 9.44”
  • Port Size: 2.06” High x 1.53” Wide
  • Runner Length: Approx. 6.5”
  • Large Plenum Volume of 549 Cubic Inches (w/ 1 x 95mm or 1 x 105mm Throttle Body Top)
  • Available With or Without Injector Ports in the Runners
  • Intakes w/ Injector Ports Include Fuel Rails w/ Dual Mounting (1.48” or 2.56” O-ring to O-ring injector length)
  • Fuel Rails are Anodized, Laser Etched, and Machined for 8AN O-Ring Fittings at Each End
  • Rear of Plenum Machined for MAP & 3 Vacuum Ports
  • Head Flange has Clearance for Fuel Supply to High Pressure Pump
  • Increased Runner Wall Thickness for Custom Porting at the Plenum to Runner Entry on Each Runner
  • O-Ring Seals at Cylinder Heads & Plenum Top
  • Easy Assembly w/ Top Mounted Screws on Plenum Top (all except front 2 screws)
  • Several Top Options: 1 x 95mm, 1 x 105mm, 2 x 4150, 2 x 4500, or Blank Flange for Custom Throttle Bodies
  • 3500-8000+ RPM Power Band

Installation Instructions

Some parts are not legal for use in California or other states with similar laws/regulations

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