Advanced Induction Cylinder Head Development
100% CNC'd High Compression 219cc GM LS1 Cylinder Head Package

GM's #241 5.7L LS1 head casting is one of the most commonly available GM castings out there.  While often swapped out in favor of 243's, the venerable 241 is still capable of producing great power for the $ considering how cheaply the castings can be obtained.  Of the features of the 241 that are less than ideal, the large open chamber is the primary detraction. With our High Compression 241 CNC work we have managed to not only alleviate the issue, but to create a chamber design as good or better than the vaunted 243 casting.  No longer will 241 applications be forced to trade compression for piston to valve clearance.  Our HCR 241 will generate 11:1 compression on a stock 346cid LS1 while retaining the stock available P2V which allows the use of large duration cams without cutting piston reliefs!  Static compression ratios into the 12.X:1 range are possible.  Furthermore, at only 15 cc over stock volume this particular porting option sees gains of over 55 cfm on the intake utilizing a factory GM 2.00" valve.  Typical gains for this CNC work are in the 40-55rwhp SAE range over the as cast 241, and 346cid LS1's can manage 440-470rwhp SAE with bolt ons and one of our daily drivable HR cam grinds.

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 (52 - 64 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: $1395

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





Please Contact Us for shipping & turnaround quotes!