{"product_id":"prc-ls3-as-cast-257cc-rectangle-port-cylinder-heads-68cc-chamber","title":"PRC LS3 As-Cast 257cc Rectangle-Port Cylinder Heads — 68cc Chamber","description":"\u003cp\u003e\u003cstrong\u003ePRC LS3 As-Cast 257cc Rectangle-Port Cylinder Heads — 68cc Chamber\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003ePart Number: PRC-SSLS3AC\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003ePrecision Race Components PRC-SSLS3AC cylinder heads are high-flow as-cast LS3-style rectangle-port heads designed for LS3, L99, L92, LSA, and LS9 applications. The heads combine 257cc as-cast intake runners with CNC-machined 68cc combustion chambers and valve-guide machining, providing a strong airflow increase without requiring a fully CNC-ported intake runner.\u003c\/p\u003e\n\u003cp\u003ePRC flow-bench testing reports up to 369 CFM of intake airflow at 0.650-inch valve lift. The casting uses a thicker deck surface intended for power-adder applications, relocated valves with a 13-degree valve angle, 2.170-inch hollow-stem stainless-steel intake valves, and 1.600-inch stainless-steel exhaust valves. The assembled set is supplied with TSP .660-inch dual valve springs using PAC springs and titanium retainers.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eKey Features\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e257cc as-cast LS3-style rectangle-port intake runners\u003c\/li\u003e\n\u003cli\u003e68cc CNC-machined combustion chambers\u003c\/li\u003e\n\u003cli\u003eCNC-machined valve-guide areas\u003c\/li\u003e\n\u003cli\u003ePRC flow-bench tested intake airflow up to 369 CFM\u003c\/li\u003e\n\u003cli\u003eThicker deck surface for improved cylinder-head clamping strength in high-load applications\u003c\/li\u003e\n\u003cli\u003eRelocated valves with 13-degree valve angles\u003c\/li\u003e\n\u003cli\u003e2.170-inch hollow-stem stainless-steel intake valves\u003c\/li\u003e\n\u003cli\u003e1.600-inch stainless-steel exhaust valves\u003c\/li\u003e\n\u003cli\u003eTSP .660-inch dual valve-spring package with PAC springs\u003c\/li\u003e\n\u003cli\u003eTitanium valve-spring retainers\u003c\/li\u003e\n\u003cli\u003eUses factory LS3-style rocker arms\u003c\/li\u003e\n\u003cli\u003eCast and machined in the USA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eKit Includes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePair of fully assembled PRC LS3 as-cast cylinder heads\u003c\/li\u003e\n\u003cli\u003e2.170-inch hollow-stem stainless-steel intake valves\u003c\/li\u003e\n\u003cli\u003e1.600-inch stainless-steel exhaust valves\u003c\/li\u003e\n\u003cli\u003eTSP .660-inch dual valve springs with PAC springs\u003c\/li\u003e\n\u003cli\u003eTitanium retainers\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eTechnical Specifications\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eIntake port configuration: LS3-style rectangle port\u003c\/li\u003e\n\u003cli\u003eIntake runner volume: 257cc\u003c\/li\u003e\n\u003cli\u003eCombustion chamber volume: 68cc\u003c\/li\u003e\n\u003cli\u003eCombustion chamber finish: CNC machined\u003c\/li\u003e\n\u003cli\u003eValve angle: 13 degrees\u003c\/li\u003e\n\u003cli\u003eIntake valve diameter: 2.170 in\u003c\/li\u003e\n\u003cli\u003eIntake valve construction: Hollow-stem stainless steel\u003c\/li\u003e\n\u003cli\u003eExhaust valve diameter: 1.600 in\u003c\/li\u003e\n\u003cli\u003eExhaust valve material: Stainless steel\u003c\/li\u003e\n\u003cli\u003eValve-spring configuration: TSP .660-inch dual spring kit with PAC springs\u003c\/li\u003e\n\u003cli\u003eRetainers: Titanium\u003c\/li\u003e\n\u003cli\u003eRocker-arm compatibility: Factory LS3-style rocker arms\u003c\/li\u003e\n\u003cli\u003ePublished peak intake flow: 369 CFM @ .650-inch lift\u003c\/li\u003e\n\u003cli\u003ePublished peak exhaust flow: 233 CFM @ .650-inch lift\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003ePublished Flow Data\u003c\/strong\u003e\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eValve Lift\u003c\/th\u003e\n\u003cth\u003eIntake Flow\u003c\/th\u003e\n\u003cth\u003eExhaust Flow\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e.200 in\u003c\/td\u003e\n\u003ctd\u003e153 CFM\u003c\/td\u003e\n\u003ctd\u003e114 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e.300 in\u003c\/td\u003e\n\u003ctd\u003e233 CFM\u003c\/td\u003e\n\u003ctd\u003e163 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e.400 in\u003c\/td\u003e\n\u003ctd\u003e287 CFM\u003c\/td\u003e\n\u003ctd\u003e191 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e.500 in\u003c\/td\u003e\n\u003ctd\u003e329 CFM\u003c\/td\u003e\n\u003ctd\u003e214 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e.600 in\u003c\/td\u003e\n\u003ctd\u003e357 CFM\u003c\/td\u003e\n\u003ctd\u003e228 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e.650 in\u003c\/td\u003e\n\u003ctd\u003e369 CFM\u003c\/td\u003e\n\u003ctd\u003e233 CFM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cstrong\u003eApplication Notes\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePRC\/Texas Speed lists these heads for LS3, L99, L92, LSA, and LS9 applications using the LS3-style rectangle-port intake architecture.\u003c\/li\u003e\n\u003cli\u003eThe LS3-style rectangle-port configuration requires a compatible LS3\/L92-style intake manifold and corresponding intake-port components.\u003c\/li\u003e\n\u003cli\u003eThe 68cc chamber is the standard configuration for PRC-SSLS3AC. Final compression ratio depends on displacement, piston configuration, deck height, head-gasket dimensions, and actual chamber volume.\u003c\/li\u003e\n\u003cli\u003eThe thicker deck surface is intended to improve head retention and sealing margin in boosted, supercharged, nitrous, and other high-cylinder-pressure combinations.\u003c\/li\u003e\n\u003cli\u003ePushrod length, piston-to-valve clearance, and complete valvetrain geometry should be verified for the specific engine and camshaft combination.\u003c\/li\u003e\n\u003cli\u003eHead gaskets, head bolts or studs, rocker arms, pushrods, intake manifold, exhaust components, and installation gaskets\/hardware are not listed as included with this cylinder-head set.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eEmissions and Competition-Use Notice\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cem\u003eThis product is not legal for sale or use in the state of California. Installation or use on an emissions-controlled vehicle may also be restricted by federal, state, or local law. The purchaser and installer are responsible for confirming that the completed vehicle and application comply with all applicable emissions and vehicle-use requirements.\u003c\/em\u003e\u003c\/p\u003e","brand":"Precision Race Components (PCR)","offers":[{"title":"Default Title","offer_id":46322705236025,"sku":null,"price":2499.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0809\/8512\/9017\/files\/7650_1.webp?v=1786726734","url":"https:\/\/rad-power.com\/products\/prc-ls3-as-cast-257cc-rectangle-port-cylinder-heads-68cc-chamber","provider":"RAD","version":"1.0","type":"link"}