Most of you are already familiar with my full CNC line of cathedral heads.....the MMS 220's and the MMS 235's probably the most popular, but like most things in life the quality of the heads and the CNC time required to build them brings a higher price tag with the final product as well. While the performance gains warrant the price of admission, my goal with the new Sportsman line was to produce a head close in flow and performance but offer the consumer a substantial reduction in cost which is always extremely challenging and difficult to do (especially if your as detail oriented as I tend to be and sweat all the details).
My new heads are a bit of a hybrid of sorts incorporating as cast surfaces to save five axis CNC porting time, but they do incorporate full CNC chambers for consistency there (a very critical area for flow and the combustion process). In addition to that the MMS 223 heads will also include hand finishing in the bowls (at no additional cost) creating a seamless blend from the valvejob to the intake and exhaust ports. This process is time consuming but critical to ensure consistency of flow in an as cast port design....without this additional effort, you could leave 10-15 CFM on the table easily due to steps and bad transitions in the most important part of the flow path (air entering and exiting the valve job).
Let me summarize by saying this....my goal with the less expensive MMS 223 Sportsman head was to get as close in performance/flow as possible to the MMS 220 full CNC piece...both heads designed to optimize any 3.900 bore application, a 346 and a 383 being the most popular. Perhaps one of the best independent results showcasing the potential of the MMS 220 design is DarthV8r's F-Body with a 227 cam that produced a tad short of 500 RWHP; a build that was well documented all along it's journey and a good read for those who missed it. While there are others of notoriety as well, DarthV8r's sticks out as a shining accomplishment of what I always knew the MMS 220 head to be capable of. I knew 500 RWHP with a small cam was within reach because of what I personally achieved a decade ago with the original (and first aftermarket cathedral) head I designed in 2004 (the AFR 205) which produced 475-480 RWHP on a half a dozen different dyno's at the time with only a 224/228 cam (my new MMS 220 and the MMS 223 offering even more potential with an additional 20 CFM of intake airflow).
I say all this to try and convey how good the new Sportsman 223 head actually is and the value play it offers you guys.
Is it as good as the full CNC MMS 220? No....that would not have been realistic but its alot closer than I expected it would be. In fact the intake port, flowed on a 3.900 bore, is about the same (give or take a CFM or two)....some lifts higher, some lifts lower but due to a slightly larger port, is not quite as efficient as the smaller MMS 220 head. The higher lift exhaust flow is where the largest difference lies with similar numbers from .200 - .400 lift....after that the as cast port gives up a little and finishes 10 CFM shy of the full CNC 220 head at .600 lift. When the smoke clears I think the difference in actual performance will be modest and the value this head offers quite apparent.
Here are the numbers on a 3.900 bore.....they flow over 320 CFM in a 4" or larger bore btw and would make an excellent choice for a 6.0 liter motor as well.
Lift......Int.....Exh
.200....150....125
.300....213....182
.400....261....215
.500....297....226
.550....311....230
.600....317....233
Complete the package with Yella Terra LS1 Roller Rockers.
