Advanced Induction Cylinder Head Development
100% CNC'd 270 & 280cc GM 821 LS3, LSA, & LS9 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 always preferable for high RPM power, or high displacement builds.  Due to the efficiency of the port design, none of the options 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
  • Deburring of Entire Casting + fine detail softening of all edges in & around combustion chambers
  • Professionally Setup & Assembled for your individual application - Ready to bolt-on & Run
Machining & Labor Cost: $1795

Ai 280cc CNC'd heads including New GM LS3 821's with the Hollow LS3 intakes: $3195 + Spring Setup
We keep these in stock so they can be milled to your desired volume or valve drop, built with an appropriate spring setup (add one from below), and shipped by the time your payment clears.  A great option for guys who lack good cores to use as a base, want all new parts, or cannot wait to have their own heads ported.  Suggested setup: Add a PSI Maxlife Beehive 1511 ($320) or 1516 ($360).

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 valves are high quality, durable, and lightweight.  Most applications do not need an aftermarket 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

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
Ai Lightweight Tool Steel Retainers for beehive style springs, under 1g heavier than most Ti beehive retainers - Cost: $200
Ai Ultimate HR Spring Kit w/ PSI MaxLife endurance springs + Ai Lwt Tool Steel retainers, machined locks, etc. - Cost: $600
BTR .660" Polished Dual Spring Kit w/ locators, viton seals, & Titanium Retainers - Cost: $310
BTR - Any other common spring kit sold by BTR is an option - Cost: BTR Price
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

Manley Race Series Stainless Steel Valves - Cost: $175 Intake OR Exhaust, $350 Both Intake AND Exhaust
Manley Hollow Stemmed Stainless Steel Intake Valves (11-12g lighter than solid stemmed intakes) - Cost: $495
Manley Severe Duty High EGT Stainless Steel Exhaust Valves (High HP power adder applications) - Cost: $275
Manley Extreme Duty High EGT Inconel Exhaust Valves (Max Effort power adder applications) - Cost: $475




Dyno, Flow Bench, and Track Results: