LS1

4.8/5.3/5.7 - RLD Performance LS1 head has slightly less average and peak flow than a stock LS3 cylinder head.  This is an outstanding small displacement cylinder head. However, this is the same price as the LS2/LS6.  This head series is a stage III street/strip/race head for smaller bore engines.  The heads are sold as new GM castings or on an exchange basis.  These heads are built to order with proprietary upgraded CNC ports, customer specified valve train parts and specified valves.  Our standard 4.8/5.3/5.7 heads all flow the same and have the same valve size and runners after machining.  The main difference is the exhaust port which is round rather than a "D" shape.  The round port actually has less flow loss through the exhaust manifold or header when tested but LS2/LS6 enthusiasts insist on the "D" port regardless of the flow.  Another advantage is that we use new or exchange factory castings and the part numbers are not ground off like some of our competitors.  Polishing the runners add between 6-7 CFM at each lift point.  The flow is comparable to the AFR 205 head. 

CombC=                                        62                            67                        

RunnerCC= 217                          200  70                     200  70          

Valve =2.0  1.55                       1.89 1.55                   2.0  1.57

RLD CNC                   VS     Stock 4.8/5.3L    VS     Stock 5.7L

Lift    I       E     E/I                 I     E     E/I                I      E    E/I    

.200  132   109  83%              128   93   73%             122   97   74%      

.300  187   147  79%              179  121  68%             178  133  75%

.400  238   175  74%              210  145  69%             215  156  73% 

.500  274   193  70%              218  163  75%             219  170  78% 

.550  281   202  72%              221  168  76%             223  176  79% 

.600  281   206  73%              226  174  77%             227  180  79%

AVG 232   172  74%             197  144  73%             197  152  77%

 RLD Performance, P.O. Box 890066, Temecula, CA 92589 (951) 676-4948, 9am-5pm Pacific Standard Time M-F, stan@rldperformance.com