Product Description
Frankenstein M311 Monster Series 11 Degree LS3 Cylinder Head Pair
Fits 4.000" and Larger Bore LS Engines when used with a Rectangle Port (LS3) Style Intake Manifold
Currently accepting pre-orders. Expected to ship early February 2025
The Monster Series M311 273cc LS3 Cylinder Heads are engineered for serious performance enthusiasts seeking unmatched power and reliability. Fully CNC-ported and constructed with high-quality components, these heads deliver exceptional airflow and combustion efficiency, making them ideal for racing applications as well as high performance street builds.
Designed to feed high-RPM stock bottom ends or larger displacement stroker engines, the M311 heads feature a 5-Axis CNC ported intake and exhaust chambers, meticulously hand-blended and deburred for maximum performance. They provide exceptional flow characteristics, with flow testing that sets a benchmark in the industry. For those who demand maximum power from their LS engine, the M311 cylinder heads are the ultimate choice!
Key Features:
• Fully CNC Ported: Featuring a 273cc intake port and 112cc exhaust port, with a 68cc combustion chamber volume and 11 degree valve angle, these heads maximize airflow and provide increased power potential for both street and race builds.
• Proven Performance: The 273cc intake port has been flow bench tested to an impressive 394.0 cfm on the intake side and 274.0 cfm on the exhaust side, providing the airflow needed for high-performance builds.
• Perfect for High-Rev and Stroker Builds: Ideal for high-RPM stock bottom end builds or larger displacement stroker engines, these heads are engineered to meet the airflow demands of aggressive applications.
• Heavy Duty Construction: Extra-thick deck surfaces are included to alleviate head gasket sealing issues, especially in power-adder applications such as forced induction or nitrous systems
• Premium Components:
• Black Nitride Stainless Steel Severe Duty Valves
• Custom PAC .700” Lift Valve Springs for Hydraulic Roller Camshafts, includes Titanium Retainers
• O-Ringed Exhaust Ports (Hi-Temp Silicone O-rings included)
• 6 Bolt Pattern: Can be used on Aftermarket 6 bolt blocks or Factory 4 bolt blocks
Specifications:
- Minimum Bore Diameter: 4.000”
- Intake Port Volume: 273cc
- Exhaust Port Volume: 112cc
- Combustion Chamber Volume: 68cc
- Intake Valves: FED Prime Grade Stainless Steel 2.165”
- Exhaust Valves: FED Prime Grade Stainless Steel 1.600”
- PAC Valve Springs: Dual .700” for Hydraulic Roller
- Retainers: FED Titanium-64 – LS Dual Spring
- Valve Locks: GM Valve Locks
- Valve Seals: Viton High Heat Seal
- Exhaust Gaskets: High Temp Silicone O-Rings
- Head Gaskets: Requires head gaskets with a minimum 4.030" bore size. LS9 Gaskets (4.100" bore) recommended for most factory-block applications.
- Spark Plugs: Compatible with .750” Reach Gasket Seat or .708" Reach Tapered Seat Plugs
- Pushrods: Depending on camshaft, lifter and rocker arm selection, typical required pushrod length will be in the 8.100-8.250" range. 3/8" Diameter recommended
- Rockers: Accepts Standard LS3 Style Rockers (Billet M311 Stands Required)
- Rocker Stands: Requires Optional Frankenstein M311 Billet Stands #913001 for stock style rockers, or can be used with M311-specific shaft rocker kits (not included)
Heads Sold/Priced as a pair
Fits: LS3 LSA L99 L76 L77 L92 LY6 L96 L94 L9H - Also Fits LS2 LQ4 LQ9 when used with a Rectangle Port/LS3 intake manifold and LS3 rocker arms.
Note: Our next M311 batch is in production, with an estimated completion in early February. Pre-order now to secure your set!
