#14 - New Cams, New Software, New Priorities
With the discovery that there are bigger grinds out there, I’ve started playing with Engine Analyzer Plus and Pipemax to better understand the relationship between cam specs and output. The cam setup I’ll be swapping up to trades about 5 lbs-ft below 5500RPM for big gains over 6000RPM. Carrying the post peak torque power much better. If I’ve gotten the numbers in the software right, I should see peak HP gains in the 20-30whp range, and peak torque arriving right at 6500, which is right at the current land speed record.
As a result, my intake project has moved up in the priority list, I want that extra torque, even though it chokes the top end off a little bit. This simulator cannot account for any sort of ramair effect, so the potential 3% gain seen at 150mph and up is not reflected, which, will put it even stronger on top than the plot with no plenum but with big cams.
Pipemax showed numbers dead on to what Les Laidlaw built for me, optimal primary length between 20.6 and 23 inches, actual headers are 21.5” primaries. Diameters all match up as well, so, props to Les, whether you used the software or not you nailed your design right out the gate.
Where the rocket motor seems to be most limited using the software is, honestly, stroke. By increasing the stroke 6mm, the simulator anticipates a gain of 30 pound feet from 3500 to 5000 and it carries between 10 and 5 pound be more from 5000 until 8000. Those of the kind of gains that make a motor more fun to ride because the mid range torque makes it feel a lot bigger than it is.
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