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Every cylinder head is hand blended, inspected, and assembled in small batches to ensure dimensional accuracy and consistency.\u003c\/p\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003eAirflow Performance\u003c\/strong\u003e\u003c\/summary\u003e\u003cp\u003eTested on a SuperFlow bench with a 4.125” bore plate\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eIntake (Radius Entry)\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 148 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 227 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 282 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 325 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 350 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 363 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cspan\u003eExhaust (No Pipe)\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 114 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 164 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 200 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 233 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 240 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 243 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWith a 267cc CNC intake runner and optimized 96cc exhaust port, the MR 15° delivers strong mid-lift efficiency and stable high-lift airflow, ideal for aggressive hydraulic roller and race-oriented camshaft profiles while retaining factory valve geometry.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003ePremium Hardware \u0026amp; Construction\u003c\/strong\u003e\u003c\/summary\u003e\u003cul\u003e\n\u003cli\u003e6-bolt Mangum Racing LS3 casting with increased deck thickness\u003c\/li\u003e\n\u003cli\u003e15° valve angle with OEM LS3 valve spacing\u003c\/li\u003e\n\u003cli\u003e2.165” hollow stem stainless intake valves\u003c\/li\u003e\n\u003cli\u003e1.600” hollow stem stainless exhaust valves\u003c\/li\u003e\n\u003cli\u003eBronze guides\u003c\/li\u003e\n\u003cli\u003ePAC .660” dual spring package\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\u003e68.5cc 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\u003eMinimum bore: 4.000”\u003c\/li\u003e\n\u003c\/ul\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003eBuilt for High-Output Stock-Geometry Combinations\u003c\/strong\u003e\u003c\/summary\u003e\u003cp\u003eThe increased deck thickness provides added durability under elevated cylinder pressure, while the 15° valve angle maintains compatibility with stock-style piston valve reliefs and factory-based valvetrain geometry.\u003c\/p\u003e\n\u003cp\u003eThe PAC .660” dual spring system offers the stability required for serious street or race camshaft profiles, and stock pushrod length works in many applications (final length should always be verified based on camshaft and milling).\u003c\/p\u003e\n\u003cp\u003eFor builders who need to retain OEM valve angles and locations but demand serious airflow capability, the MR 15° LS3 casting delivers.\u003c\/p\u003e\u003c\/details\u003e","brand":"Mangum Racing","offers":[{"title":"PAC .650\" Double Springs","offer_id":52550852968724,"sku":null,"price":2099.99,"currency_code":"USD","in_stock":true},{"title":"TSP\/PAC .660\" Polished Springs","offer_id":52550853001492,"sku":null,"price":2099.99,"currency_code":"USD","in_stock":true},{"title":"PAC 1207x .700\" Springs","offer_id":52550853034260,"sku":null,"price":2199.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1012\/8434\/8180\/files\/15LS3.1.jpg?v=1779913907"},{"product_id":"mangum-racing-275cc-11-degree-ls3-cylinder-heads","title":"Mangum Racing 275cc 11 degree LS3 Cylinder Heads","description":"\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. 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The result is a cylinder head designed for serious big boost or naturally aspirated, large cubic inch \/ high-RPM LS combinations where maximum horsepower is the priority.\u003c\/p\u003e\n\u003cp\u003eFeaturing a \u003cb\u003e12° valve angle\u003c\/b\u003e, \u003cb\u003eOEM LS7 valve spacing\u003c\/b\u003e, and robust \u003cb\u003e6-bolt Brodix casting\u003c\/b\u003e, this package provides exceptional airflow capability with the structural integrity required for high-output boosted combinations as well.\u003c\/p\u003e\n\u003cp\u003eEach set is fully CNC machined in-house on our Centroid 5-axis machining centers, finished on Newen seat and guide equipment, then hand blended, assembled, and inspected in small batches to ensure elite quality and repeatable performance.\u003c\/p\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003eAirflow Performance\u003c\/strong\u003e\u003c\/summary\u003e\u003cp\u003e\u003cb\u003eTested on a SuperFlow 1020 with a 4.125” Bore Plate\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eIntake (Radius Entry)\u003c\/b\u003e\u003cbr\u003e.200” – 167 CFM\u003cbr\u003e.300” – 254 CFM\u003cbr\u003e.400” – 313 CFM\u003cbr\u003e.500” – 359 CFM\u003cbr\u003e.600” – 388 CFM\u003cbr\u003e.700” – 410+ CFM\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eExhaust (No Pipe)\u003c\/b\u003e\u003cbr\u003e.200” – 117 CFM\u003cbr\u003e.300” – 160 CFM\u003cbr\u003e.400” – 209 CFM\u003cbr\u003e.500” – 224 CFM\u003cbr\u003e.600” – 235 CFM\u003cbr\u003e.700” – 247 CFM\u003c\/p\u003e\n\u003cp\u003eThe Mangum Racing 283 BR7 offers exceptional mid-lift efficiency with dominant high-lift airflow, making it an outstanding option for max-effort street\/strip and race-focused LS builds.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003ePremium Hardware \u0026amp; Construction\u003c\/strong\u003e\u003c\/summary\u003e\u003cul style=\"margin-top: 0in;\"\u003e\n\u003cli\u003e6-bolt Brodix BR7 LS7 casting\u003c\/li\u003e\n\u003cli\u003e12° valve angle with OEM LS7 valve spacing\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eStock valve lengths\u003c\/li\u003e\n\u003cli\u003e283cc CNC intake port\u003c\/li\u003e\n\u003cli\u003e93cc exhaust port\u003c\/li\u003e\n\u003cli\u003e70.5cc CNC combustion chambers (milling available at no charge)\u003c\/li\u003e\n\u003cli\u003e2.250\" Oversized titanium intake valves\u003c\/li\u003e\n\u003cli\u003eStainless exhaust valves\u003c\/li\u003e\n\u003cli\u003eBronze guides\u003c\/li\u003e\n\u003cli\u003ePAC .660” dual spring package\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\u003eChamber softening available\u003c\/li\u003e\n\u003cli\u003eFlat milling at .006” per cc\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cb\u003eMinimum Bore:\u003c\/b\u003e 4.100”\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003e\u003cstrong\u003eDesigned for Maximum LS7 Performance\u003c\/strong\u003e\u003c\/summary\u003e\u003cp\u003eWith airflow exceeding \u003cb\u003e400 CFM\u003c\/b\u003e, the Mangum Racing 283 BR7 is engineered for customers seeking elite horsepower capability from an LS7-based cylinder head. This package is ideally suited for large cubic inch naturally aspirated combinations, aggressive camshaft applications, and high-output boosted builds where ultimate airflow and top-end power take priority.\u003c\/p\u003e\n\u003cp\u003eStock pushrod length works in many applications but should always be verified based on camshaft selection and final milling.\u003c\/p\u003e\u003c\/details\u003e","brand":"Mangum Racing","offers":[{"title":"TSP\/PAC .660\" Polished Springs","offer_id":52550909559060,"sku":null,"price":3999.99,"currency_code":"USD","in_stock":true},{"title":"PAC 1207x .700\" Springs","offer_id":52550909591828,"sku":null,"price":4099.99,"currency_code":"USD","in_stock":true},{"title":"PAC 1208x .750\" Springs","offer_id":52550909624596,"sku":null,"price":4099.99,"currency_code":"USD","in_stock":true},{"title":"PAC 1209x .750\" Springs","offer_id":52550909657364,"sku":null,"price":4099.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1012\/8434\/8180\/files\/BrodixLS7.1.jpg?v=1779916505"},{"product_id":"mangum-racing-229cc-ls1-cylinder-heads-4-8l-5-3l-5-7l-6-0l","title":"Mangum Racing 229cc LS1 Cylinder Heads (4.8L\/5.3L\/5.7L\/6.0L) 4 Bolt Casting","description":"\u003cp\u003e\u003cspan\u003eMangum Racing CNC Ported MR 15° LS Cathedral Port Cylinder Heads\u003c\/span\u003e\u003c\/p\u003e\n\u003cp\u003eBuilt from your choice of 4-bolt or 6-bolt 15° LS casting featuring increased deck thickness, the MR 15° LS1 is engineered for serious naturally aspirated and boosted combinations that demand airflow, strength, and repeatability, while maintaining OEM valve angle and valve location geometry.\u003c\/p\u003e\n\u003cp\u003eFeaturing a 2.02\/1.57 valve combo the 229cc version easily clears the bores on 4.8L\/5.3L engines and up!  This is not a simple LS6 cylinder head copy, this is a ground up designed cylinder head with fully cnc ported ports \u0026amp; chambers for optimum power \u0026amp; performance.\u003c\/p\u003e\n\u003cp\u003eThis casting is designed to support\u003cspan\u003e \u003c\/span\u003e\u003cspan\u003e1,500+ horsepower\u003c\/span\u003e\u003cspan\u003e \u003c\/span\u003ecombinations when paired with the proper short block and induction system, making it an ideal solution for builders who need maximum performance without moving away from stock valve layout.\u003c\/p\u003e\n\u003cp\u003eEach set is fully CNC ported in-house on new Centroid 5-axis machining centers and finished on Newen seat and guide equipment. Every cylinder head is hand blended, inspected, and assembled in small batches to ensure dimensional accuracy and consistency.\u003c\/p\u003e\n\u003cdetails open=\"\"\u003e\n\u003csummary\u003e\u003cstrong\u003eAirflow Performance\u003c\/strong\u003e\u003c\/summary\u003e\n\u003cp\u003eTested on a SuperFlow bench\u003c\/p\u003e\n\u003cp\u003e\u003cspan\u003eIntake (Radius Entry)\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 138 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 207 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 260 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 293 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 315 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 321 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cspan\u003eExhaust (No Pipe)\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e.200” – 109 CFM\u003c\/li\u003e\n\u003cli\u003e.300” – 154 CFM\u003c\/li\u003e\n\u003cli\u003e.400” – 198 CFM\u003c\/li\u003e\n\u003cli\u003e.500” – 223 CFM\u003c\/li\u003e\n\u003cli\u003e.600” – 235 CFM\u003c\/li\u003e\n\u003cli\u003e.700” – 240 CFM\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eWith a 229cc CNC intake runner and optimized 97cc exhaust port, the MR 15° delivers strong mid-lift efficiency and stable high-lift airflow, ideal smaller bore LS engines 3.780\"-4.00\")\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cdetails open=\"\"\u003e\n\u003csummary\u003e\u003cstrong\u003ePremium Hardware \u0026amp; Construction\u003c\/strong\u003e\u003c\/summary\u003e\n\u003cul\u003e\n\u003cli\u003e6-bolt Mangum Racing LS1 casting with increased deck thickness\u003c\/li\u003e\n\u003cli\u003e15° valve angle with OEM LS valve spacing\u003c\/li\u003e\n\u003cli\u003e4 Bolt or 6 Bolt Casting Available\u003c\/li\u003e\n\u003cli\u003e2.02” stainless intake valves\u003c\/li\u003e\n\u003cli\u003e1.57\"  stainless exhaust valves\u003c\/li\u003e\n\u003cli\u003eBronze guides\u003c\/li\u003e\n\u003cli\u003ePAC dual spring package\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\u003e62cc CNC chambers (milling available at no charge)\u003c\/li\u003e\n\u003cli\u003eChamber softening options available\u003c\/li\u003e\n\u003cli\u003eFlat milling at .007” per cc\u003c\/li\u003e\n\u003cli\u003eMinimum bore: 3.780” (4.8\/5.3)\u003c\/li\u003e\n\u003cli\u003e4.030\" minimum gasket bore\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/details\u003e\n\u003cdetails\u003e\n\u003csummary\u003e\u003cstrong\u003eBuilt for High-Output Stock-Geometry Combinations\u003c\/strong\u003e\u003c\/summary\u003e\n\u003cp\u003eThe increased deck thickness provides added durability under elevated cylinder pressure, while the 15° valve angle maintains compatibility with stock-style piston valve reliefs and factory-based valvetrain geometry.\u003c\/p\u003e\n\u003cp\u003eThe PAC dual spring system offers the stability required for serious street or race camshaft profiles, and stock pushrod length works in many applications (final length should always be verified based on camshaft and milling).\u003c\/p\u003e\n\u003cp\u003eFor builders who need to retain OEM valve angles and locations but demand serious airflow capability on a smaller bore LS engine, the MR 15° LS1 229cc casting delivers.\u003c\/p\u003e\n\u003c\/details\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Mangum Racing","offers":[{"title":"PAC .650\" Double Springs","offer_id":53261968376084,"sku":null,"price":2099.99,"currency_code":"USD","in_stock":true},{"title":"TSP\/PAC .660\" Polished Springs","offer_id":53261968408852,"sku":null,"price":2099.99,"currency_code":"USD","in_stock":true},{"title":"PAC 1207x .700\" Springs","offer_id":53261968441620,"sku":null,"price":2199.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1012\/8434\/8180\/files\/MR229LS1.1.jpg?v=1785187407"}],"url":"https:\/\/mangumracing.com\/collections\/featured-products.oembed","provider":"Mangum Racing CNC Ported Cylinder Heads","version":"1.0","type":"link"}