Guzzi Cylinder Head Flow Bench Data- compiled by Ed Milich

EV Heads
   The following flow data comes from Sidney Conn’s ’98 EV 1100 heads. Figures 1-3 show before and after results of Mike Rich’s (of Mike Rich Motorsports, 866-676-7767) porting job on the heads. Note from the graph that most of the flow gains come at the higher valve openings. The lower valve openings are thus valve-orifice–limited. Thus, the more cam lift and duration that you have, the more pronounced the effects of the port work.
Figure 2: EV Head Flow Data
Figure 1: EV Head Flow Graph
Figure 3: More EV Head Flow Data
Lemans IV Heads
   The following flow data comes from Ed Milich's Lemans IV heads. Figures 4-6 show flow data before and after a stage 1 port job. The heads were otherwise stock. The heads have had further work, so this data is not current. For other reasons, I was not too impressed with the guy who did the port work. As seen here, the flow gains are on the order of 5%.
Figure 6: More LM IV Head Flow Data
Figure 4:LM IV Head Flow Graph (higher flow line at high lift is the result of port job)
Figure 5: LM IV Head Flow Data
Roundfin Convert Heads
   The following flow data comes from Mike Wright's reworked Convert heads. Figures7-10 show flow data before and after a stage 2 port job and an increase to Lemans spec valves (44/37mm In/ Ex). Note the additional restriction that develops when the 40mm carbs are added.
Figure 9:  Convert Head Flow Data
Figure 8:  Convert Head Flow Data
Figure 7: LM I spec Convert Head Flow Graph
Figure 10:  Convert Head Flow Data