Longer stacks might help the 60’.
No telling what would happen down track though.
Hey Dwayne
This program APP I use is very close to what I have found on the dyno with IR intake set ups, not every engine reacts the same [ CID, CSA of port,cam,, ect ] but my engine is close to the ones I have dynoed, that said, the runner length helps at a given RPM & hurts power at other RPMS that is not in the usable range of said length, right now my set up is 17" runner.
Input length is 17 inches
For 2nd harmonic, RPM range is from 6911 to 8386 with a pulse strength of 10 percent
For 3rd harmonic, RPM range is from 5192 to 5934 with a pulse strength of 7 percent
For 4th harmonic, RPM range is from 4048 to 4527 with a pulse strength of 4 percent
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I am using the 3rd harmonic pulse right now , the 2nd pulse is above my RPM range
the 4th is bellow my converter stall.
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Looking at my coverter stall on the data log, I am at 4800 rpm at the leave,,,so that means that my engine is in the bad part of the good harmonic pulse range 5192 to 5934 with a pulse strength of 7 percent.
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Input length is 24 inches
For 2nd harmonic, RPM range is from 4895 to 5940 with a pulse strength of 10 percent
For 3rd harmonic, RPM range is from 3678 to 4203 with a pulse strength of 7 percent
For 4th harmonic, RPM range is from 2867 to 3207 with a pulse strength of 4 percent
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Now going to a Total runner length of 24" will move the power making benefit of the runner to the 2nd harmonic pulse of 4895 to 5940 with a pulse strength of 10 percent, so by doing that should put my engine in the power range on the leave at 4800 rpm & my trap rpm of about 6k fits with the 17" AND 24" runner, also the pulse is stronger on the 2nd harmonic.
So the longer runner should not hurt the big end at all.
I had cut my runners to 17" so I could see over the air filters to drive on the street,.
