{"product_id":"mangum-racing-275cc-11-degree-ls3-cylinder-heads","title":"Mangum Racing 275cc 11 degree LS3 Cylinder Heads","description":"\u003ch2\u003eMangum Racing 275cc 11° LS3 Cylinder Heads\u003c\/h2\u003e\n\u003cp\u003e\u003cspan\u003eMangum Racing CNC Ported MR275 11° LS3 Cylinder Heads\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eBuilt from the Mangum Racing 6-bolt 11° LS3 casting featuring a massive .750” deck surface, the MR275 is designed for maximum-effort naturally aspirated and boosted LS combinations where airflow, strength, and valvetrain stability are non-negotiable.\u003c\/p\u003e\n\u003cp\u003eThis casting was engineered for builders who want every available advantage — valve angle, deck thickness, port efficiency, and piston-to-valve clearance — all optimized to support serious compression and high cylinder pressure environments.\u003c\/p\u003e\n\u003cp\u003eEach set is fully CNC machined in-house on brand new Centroid 5-axis machining centers and finished on Newen seat \u0026amp; guide equipment. Every head is hand blended, inspected, and assembled in small batches to ensure repeatability and precision.\u003c\/p\u003e\n\u003ch3\u003eAirflow Performance\u003c\/h3\u003e\n\u003cp\u003eTested on a SuperFlow bench with a 4.125” bore plate\u003c\/p\u003e\n\u003cp\u003eIntake (Radius Entry)\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 143 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 221 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 283 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 330 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 358 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 381 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eExhaust (No Pipe)\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 112 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 161 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 202 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 232 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 242 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 248 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWith a 275cc CNC intake runner and optimized 98cc exhaust port, the MR275 delivers exceptional mid-lift efficiency with dominant high-lift airflow. The 11° valve angle significantly improves piston-to-valve clearance, allowing aggressive cam timing and higher compression strategies without compromise.\u003c\/p\u003e\n\u003ch3\u003ePremium Hardware \u0026amp; Construction\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e6-bolt Mangum Racing 11° LS3 casting with .750” deck thickness\u003c\/li\u003e\n\u003cli\u003eOptimized 11° valve angle and revised valve locations\u003c\/li\u003e\n\u003cli\u003e2.185” hollow stem stainless extended-length intake valves\u003c\/li\u003e\n\u003cli\u003e1.600” stainless extended-length exhaust valves\u003c\/li\u003e\n\u003cli\u003eBronze guides\u003c\/li\u003e\n\u003cli\u003eChoice of PAC 1207X, 1208X, or 1209X dual spring packages\u003c\/li\u003e\n\u003cli\u003eTitanium retainers\u003c\/li\u003e\n\u003cli\u003eViton seals\u003c\/li\u003e\n\u003cli\u003e1.250” steel spring seats\u003c\/li\u003e\n\u003cli\u003e70.5cc fully CNC chambers (milling available at no charge)\u003c\/li\u003e\n\u003cli\u003eChamber softening options for 4.000”, 4.065”, and 4.125” bore sizes\u003c\/li\u003e\n\u003cli\u003eFlat milling at .006” per cc\u003c\/li\u003e\n\u003cli\u003eSubstantial piston-to-valve clearance for advanced camshaft profiles and compression increases\u003c\/li\u003e\n\u003cli\u003eMinimum bore: 4.000”\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eBuilt for Maximum Effort Combinations\u003c\/h3\u003e\n\u003cp\u003eThe increased deck thickness supports extreme cylinder pressure in large displacement and boosted applications. The revised 11° valve angle enhances airflow efficiency while providing additional mechanical clearance — a critical advantage in high-rpm, high-lift camshaft programs, or builds where smaller combustion chambers are required.\u003c\/p\u003e\n\u003cp\u003eThese heads have supported combinations exceeding 2,000 horsepower and 200+ mph in competition environments, making the MR275 a proven solution for serious LS3-based builds.\u003c\/p\u003e\n\u003cp\u003eIf you are building a no-compromise LS3 combination — naturally aspirated or power-adder — the MR275 was designed for exactly that purpose.\u003c\/p\u003e","brand":"MailOrder Tuner","offers":[{"title":"Default Title","offer_id":51841274904877,"sku":"MR-27511DLS3","price":3099.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0253\/3097\/4819\/files\/MR-27511DLS3.webp?v=1771882840","url":"https:\/\/mailordertuner.com\/products\/mangum-racing-275cc-11-degree-ls3-cylinder-heads","provider":"MailOrder Tuner","version":"1.0","type":"link"}