HEAD-TO-HEAD part :1

In this series we are going to be testing a variety of heads from the standard production heads to many of the newest aftermarket heads that are offered  . In conjunction with this we are testing some of the CNC ported options that many manufactures offer. Now most all manufactures  publish a advertised flow rating , but we will be testing all heads on the same flow bench so it will be an apples to apples comparison . Lets have a quick explanation of flow testing, while nothing beats real world testing of horsepower  flow testing will show you where in the opening of the valve it flows the best and if ported where your improvements were. A flow bench is ether a big vacuum cleaner  or a giant leaf blower depending on if you are testing the intake or exhaust . Then by reading the resistance in the pressure  the CFM (cubic feet per minute) can be determined

So flow testing a head is a good standard for comparing it to another head, but not every flow bench is calibrated the same so comparison from head to head is if'y at best. For our testing we will be using a Superflow 600 @ 28 inches of water at  Cleveland Performance in Cleveland Tenn.  Owner Dan Rawls is a long time Ford racer and engine  builder thus  ensuring equality between test. Now we are not saying our test are any more accurate than anyone else's , but they will accurately show the difference between heads by comparing heads on the same bench.

Our first test subjects are sure to ignite a age old debate , C8AE-H and a C1AE 352 head.  The C8 is a common head  and reflects Fords change to a smaller intake port and away from the Low Riser size port that debut in 1958 and ran through 1966 in standard production cars and trucks ( Cobra Jet used this port size till 1970) . FE fans are divided on the merits of both heads, the C8 camp points to a more balanced intake to exhaust flow ratio and low end power  , the early big port guys argue it has a higher horsepower  potential due to better flow and you only have to work on one side (exhaust) of the head to optimize it . But with early heads becoming scarce and much effort being focused on improving the later model heads they are catching on and doing well.  So let us begin  and we hope this helps  and we will be using these heads as base line to compare other heads to . We only tested up to .500 lift there was not much improvement above that and that's a pretty standard lift on factory engines
  .


                            C8AE-H                                                                C1AE
   
                INT         Lift       EXH                                          INT       Lift       EXH
                119         .200       100                                            112       .200       100
           
                162         .300       125                                            174       .300       128

                187         .400       141                                            202       .400       142
   
                193         .500       150                                            215       .500       150   
                     ratio@ .400   75%                                                ratio@ .400   70%

According to our head guy a good rule of thumb on performance engines each CFM improved is worth  an increase of 1.5-2 HP depending on the level of your build . A lot is said about flow ratio between int/exh  while this is a factor, many other things come into play and a simple dual pattern cam can help adjust balance if it is a concern. Speaking of cams having your head flow numbers is invaluable when your are getting a cam ground to fit your project and is not a terribly expensive to have done.  The reason we listed ratio of intake to exhaust flow  at mid lift  because it passes it twice in a cycle of lift. Interestingly on our test heads the exhaust flowed the same on the C8 and the C1 not bad numbers for factory 2.05/1.55 valves. So no matter which head  your run your FE has the potential to make good power and with CNC porting programs popping up at places like Craft Performance  getting a great flowing factory head is becoming more affordable.  A big thanks To Dan Rawls at Cleveland Performance Center for  the testing and tech advice.

C8AE-H intake port height

C1AE intake port height

comparison of exhaust ports
 shows similar size  hinting at
 the equal flow results