Example of Dyno Tuning

The test results below show some of the detailed information available from dyno testing. An Edelbrock Victor W-2 and a Holley Strip Dominator were tested on the same Dodge 355. A dozen or so tests showed the Holley prefered 30" header primary tubes while the Edelbrock ran best with 38+" primary tube lengths. How could this be be determined without adjustable headers and actual dyno testing? Looking closer at the graphs of the exhaust gas temperatures one can see room for even more improvements. On the test 137 graph notice the four corner cylinders run much hotter (leaner) than the center cylinders. A simple, but crude way to remedy this would be to epoxy small dams (matchsticks) in the manifold plenum in front of the center cylinder runners. This would direct more wet flow to the outer cylinder runners and have the effect of evening out the egts allowing further carb tuning. Notice cylinder #3 on the bottom (Edelbrock) graph. The same trick could be applied here. How does knowing details like this help? Well it could save cylinder #3 from destruction under racing conditions. By modifying the Holley manifold one could get the egts as close as they are with Edelbrock manifold.

Test Results 16k

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