Before removing the Mummert aluminum heads from the dyno mule engine, a morning was spent in trying several other intake setups on the heads.  Final conclusion is that many of the early intake designs are going to be a bottleneck on the aluminum heads in the upper rpm ranges.  No surprise there as I see this also on ported iron heads.  For many of these intakes though, the low end torque values were still very strong which is a credit to the flow properties of the new aluminum heads.  The Mummert aluminum single four intake is still by far the best overall performer of all the intakes tested to this point and compliments the aluminum heads nicely.

The Cain 4V intake was tested at the tail end of this particular session and although the horsepower numbers with the Cane intake were stronger than the 3X2 and 2X4 setups with the aluminum heads in place, the torque curve still remains on the low side and lazy.   But compared to the last time the Cane intake was tested, the overall torque curve is much higher with this engine combination than as tested before.  The use of long tube headers in this recent test versus the short 'two tube' design used in the earlier test possibly accounts for most of the torque improvement.  Regardless, the open plenum and runnerless design of the Cain intake just isn’t conducive to making good peak torque numbers even when experimenting with a variety of carb spacers.  Here’s the graphs showing the Cain intake manifold’s best performance on the aluminum heads versus when it was used previously on a set of highly ported iron heads on a similarly sized engine.  Camming and headers were different on the two different engines being tested so it’s not an apples to apples test.

Lorena, Texas (South of Waco)