Anti-Reversionary Cones Dyno Test

 

Anti-reversion cones are a device you put into your head pipes, near the cylinder head, to discourage reversion (i.e. a positive pressure wave in the pipe that interferes with cylinder fill if it arrives during overlap). Some are bell shaped like pictured above and others are a pure cone shape.

 

At various times I've tested these things (both styles) on exhaust systems that both showed and didn't show evidence of reversion. The results have always basically been about the same ...

 

 

 

They always seem to either cause a small loss over a wide range, or on occassion I'll see a small loss at only higher rpm's.

 

My guess is they'd be more effective on a system where the pipe was oversized for the motor size and target rpm. I'll continue to test these as I get time and if I get a result on a particular setup where they show a real advantage I'll report back. In the meantime, it's not high on my list of worthwhile performance mods.

 

 

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