Advanced Induction Cylinder Head Development
100% CNC'd 232cc Big Valve GM LS6/LS2 Cylinder Head Package

This is a version of our 232cc full CNC work with a larger 2.055" / 1.575" valve set instead of the stock 2.00" / 1.500" valves.  It is mainly helpful on 4" & larger bore applications running large high lift cams, and adds approximately 15-30hp potential to the head depending on build (stock short block vs. more stroke / RPM).  This can put 6L stock short blocks over 500rwhp, and strokers well over 500rwhp.  The highest #'s reported for a typical hydraulic roller street build have been over 550rwhp / 525rwtq SAE on a Dynojet.  It can be particularly helpful for 4" stroke apps.  Works best with at least 230deg of cam & .62X" net lift.  Properly running the larger valve entails cutting out the stock seat inserts, and machining the seat counterbore for a larger aftermarket seat insert to ideally fit the 2.055" intake.  The premium over the standard 232cc CNC work includes the additional machining, aftermarket intake seats, and a full set of Manley Race Series Stainless Steel valves.

Pricing is for work applied to a pair (2) of cylinder head castings and components YOU supply unless otherwise noted.  We are happy to build your heads with whichever spring kit, valve, etc. you would like.  Please keep in mind if components you provide require additional time on our part, we must bill for that.


Machining & Labor Operations:
  • 100% CNC Ported Intake, Exhaust, & Combustion Chambers
  • 100% CNC Professional Competition Quality Valvejob
  • Valves Cleaned & Precision Ground
  • Manley Race Series 2.055" Stainless Steel Intake Valves
  • Manley Race Series 1.575" Stainless Steel Exhaust Valves
  • Larger Aftermarket Intake Seat Inserts Installed
  • PCD milled to ensure flatness, surface finish, & achieve desired chamber volume (57 - 67 cc)
  • Customer can specify milling to an Available P2V Clearance relative to stock (e.g. .018" less P2V)
  • Intake Flange, Exhaust Flange, and Valve Cover Rail PCD Milled to new surface finish specs
  • Thorough Inspection of Castings, Components, Bind Heights for your individual set of springs, etc.
  • Complete Cleaning/Prep including Bead Blasting + UltraSonic to ensure internal passages are clear & free of debris
  • Deburring of Entire Casting + fine detail softening of all edges in & around combustion chambers
  • Pushrod Clearance Machined for larger pushrods + Geometry Improvement for High Lift Cams
  • Professionally Setup & Assembled for your individual application - Ready to bolt-on & Run
Machining & Labor Cost: $2195

Please Contact Us for shipping & turnaround quotes.


Labor and Component Options:

Note: GM heads often show so little guide wear that they do not need to be replaced.  In the event they do require attention due to wear or your application, we have several options.  GM OEM exhaust valves are high quality, durable, and lightweight.  Most applications do not need an aftermarket exhaust valve.

Bronze Guide Liners installed & honed to ideal clearances to refurbish worn out guides. - Cost: $250
Replace OEM guides with Ai Pro Racing Quality Full Bronze Guides & hone to ideal clearances - Cost: $295
Replace OEM guides with new Powdered Metal Guides & hone to ideal clearances - Cost: $250

PSI 1511 MaxLife Endurance Spring Kit w/ OEM Replacement Seals. - Cost: $340
PSI 1516 High Lift MaxLife Endurance Spring Kit w/ OEM Replacement Seals. - Cost: $380
Manley 23622 Titanium Retainers for OEM, PAC, PSI, etc. beehive style springs - Cost: $195
BTR .660" Polished Dual Spring Kit w/ locators, viton seals, & Steel Retainers - Cost: $230
BTR .660" Polished Dual Spring Kit w/ locators, viton seals, & Titanium Retainers - Cost: $300
Manley Nextek .660" rated shot peened & polished Dual Spring Kit w/ Titanium Retainers - Cost: $400
Manley Nextek .700" rated shot peened & polished Dual Spring Kit w/ Titanium Retainers - Cost: $660
Manley Nextek .800" rated shot peened & polished Dual Spring Kit w/ Titanium Retainers - Cost: $700

Upgrade to Manley Hollow Stemmed Intake Valves (11-12g lighter than solid stemmed intakes) - Cost: $250
Upgrade to Manley Severe Duty High EGT Stainless Steel Exhaust Valves (High HP power adder applications) - Cost: 100
Manley Extreme Duty High EGT Inconel Exhaust Valves (Max Effort power adder applications) - Cost: $250




Dyno, Flow Bench, and Track Results: