Advanced Induction Cylinder Head Development
100% CNC'd 270, 275, & 280cc GM 821 LS3 Cylinder Head Package

GM's new LS3 head represents a phenomenal leap in capacity over previous cathedral port castings.  In as-cast for this head moves only ~310 cfm at a whopping 260 cc port volume.  Keeping in mind that the LS3 is already a relatively large port we have decided to offer our full CNC porting in several sizes.  While there is not a large performance difference from 270cc to 280cc, there is a significant difference in port cleanup.  The smaller 270cc size is capable of producing an easy 600hp+ on mild builds, and has proven it will make 700hp+ on 40Xcid+ engines below 7krpm with HR cams.  However, due to significant core shift in the GM castings, there are often large areas that remain as cast.  While it does not negatively affect function, some are bothered by the aesthetics.  Those customers should request the larger 280cc version to reduce the size of areas untouched by our CNC program.  The 280cc version is also preferable for high RPM power, or high displacement builds.  For the indecisive, you can split the difference and opt for the 275cc version.  Due to the efficiency of the port design, none of the options should negatively affect drivability, and all are typically within 10-15hp of one another in most applications.

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 (whether using new aftermarket or re-using OE GM
  • PCD milled to ensure flatness, surface finish, & achieve desired chamber volume (62 - 73 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
  • Professionally Setup & Assembled for your individual application - Ready to bolt-on & Run
Machining & Labor Cost: $1195

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.

Bronze Guide Liners installed & honed to ideal clearances to refurbish worn out guides. - Cost: $150
Replace OEM guides with Ai Pro Racing Quality Full Bronze Guides & hone to ideal clearances - Cost: $250
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: $280
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: $500
Manley Nextek .700" rated shot peened & polished Dual Spring Kit w/ Titanium Retainers - Cost: $635
Manley Nextek .800" rated shot peened & polished Dual Spring Kit w/ Titanium Retainers - Cost: $700



Dyno, Flow Bench, and Track Results: