FRH GM 243/799/317 6L LS1



Seriously fresh, seriously powerful!  For those looking for aftermarket performance, these reworked factory castings offer a much more economical solution while still offering similar power potential.  Leaving the already large stock combustion chamber as‐is, the intake and exhaust ports are designed to utilize larger valves than originally equipped and CNC machined to provide superior surface finish and the ultimate in repeatability.  The new valve job is precisely matched to the new port design further increasing the efficiency of these heads.  All of the mating surfaces have been CNC milled using PCD to not only provide a flat, clean mating surface but also to correct for any angular discrepancies in the stock casting.

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Intake Volume       225-240cc

Exhaust   Volume     88cc

Chamber Volume     59-70cc  

Intake Flow (2.040" Valve)      

262cfm @ .400”            

320cfm @ .600”

Exhaust Flow (1.575" Valve)   

200cfm @ .400”        

240cfm @ .600”  

Spring kit w/ Titanium retainers included good to .660” lift  

Intake Valve Diameter    2.000” -  2.040"

Intake Seat Material    Ductile Iron 

Exhaust Valve Diameter    1.550" - 1.575"

Exhaust Seat Material    Ductile Iron 

Valve Angle      15⁰

Valve Guide Material    Bronze Alloy  

Minimum Bore Size    3.900”