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260cc 11° CNC LS3 Cylinder Heads – Smeding Performance

260cc 11° CNC LS3 Cylinder Heads


  • 100% Fully CNC Ported 260cc Intake, 100cc Exhaust & 69cc Chambers
  • Virgin A356 Aluminum Castings
  • 6 Bolt Head Casting with Extra Strength Decks
  • Advanced 11° Valve Angle for Maximum Flow & PTV Clearance
  • 2.165” Intake Valve 21-4N Alloy & 1.60” Exhaust Valve 23-8N Super Alloy
  • 23-8N Alloy has the same high temp characteristics of “Inconel” w/o the brittleness
  • Available Complete w/ Chromoly Retainers, Ti Retainers, or Bare w/ Valves
  • Billet Rocker Arm Stands Included - Compatible w/ OEM LS3 Rocker Arms
  • Compatible w/ 4 Bolt OEM Engine Blocks - 4.000" Minimum Bore Required
0.660" Spring Specs:
  • 145# @ 1.800"
  • 400# @ 1.130"
  • CB @ 1.070"
0.700" Spring Specs:
  • 170# @ 1.800"
  • 450# @ 1.115"
  • CB @ 1.000"
Valve Lift Intake Exhaust
0.200" 145 116
0.300" 219 165
0.400" 286 204
0.500" 321 225
0.600" 350 238
0.700" 369 246

Head Flow Data @ 28inHg, 4.125" Bore, Intake w/ Radius, Exhaust w/o Pipe

It MUST be noted that comparing flow data across different flow benches and cylinder heads is NOT the correct way to measure a cylinder head's performance. A flow bench measures static air flow while the engine's valve is at a stationary position. In the real world, the valve nor the air in the cylinder head's runner is ever stationary. The air/fuel mixture is constantly being pushed, pulled & pulsed by the pistons & other cylinder's valve events. A well performing cylinder head must be able to respond to the valve opening and efficiently deliver the air/fuel mixture that the engine is requiring, while also keeping turbulence to a minimum. This is where the Smeding 11° design is unbeatable. On the dyno these heads will out perform other manufacture's 12° designs, even though they advertise higher flow numbers. Below is a dyno comparison of our 11° 260cc CNC cylinder heads vs a competitors 12° CNC 260cc cylinder heads. The test engine was a mild 11.0:1 441" LS engine with our 245/256 Rectangle Port R4 Stroker camshaft. Both dyno pulls were done the same day, with both tunes optimized for each combination. As you can see the 11° Smeding heads outperformed the 12° competitor's heads across the entire curve.


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