Bolt On H.P.

[7500Blizzard]

Almost all my sleds tuned pipes measure right about there from the factory. The pipes for my Blizzard are just a bit over 13'' and that motor is 436cc's 95HP and runs at 9000rpm in sstock form.

[Mark75H]

I must have been bleary eyed when you first posted

Tuned pipes should be 12-13 inches from exh port to front side of chamber to work, And most factory tuned pipes do run right around that length.

I missed the "from exh port to front side of chamber" part. The length we are talking about would be the same as from the exhaust port all the way to the fattest part of the chamber, not just to the beginning of the diffuser cone. Now do you see why I am saying 12" is too short?

[7500Blizzard]

I've always been told to the beginning of the diffuser. I'm probably almost around 20'' to fattest part of pipe.

[Mark75H]

The critical tuned length for an expansion chamber is half way down the final cone taper. You can find this information in any technical description of an expansion chamber or description of how to design and build an expansion chamber from scratch.

[7500Blizzard]

The head pipe should be 12 inches.