First Generation Ascots > Tech Section

Dyno tuning

<< < (8/8)

scottly:
I've tested three different exhausts now. The first, that resulted in the 2+ HP increase over the stock pipe had primary tubes 26" long, measured from the sealing surface at the head, around the outside of the bends. The second used the straight lengths from the stock outer pipes to extend the length to 34". The third had 22" pipes. The 22" pipe had a slight advantage over the 26" from about 3700-5100 RPM, while the 26" had a slight advantage from about 5600-6700. The 34" pipe had a noticeable drop from about 4300-5100, but interestingly all three pipes showed the same peak torque.

scottly:
This is the next pipe up for testing:
(J, you asked about MPG; all I can say is the dyno tests of the 3 previous pipes appear to have consumed over 1 gallon of gas. ::))
 

scottly:
After testing a few different configurations of pipes, I finally settled on a design that seemed to be the best compromise of usable power band and weight. As far as being a "tuned" exhaust, I started it up without the muffler to heat up the header paint, and it rattled my ear drums! I did a couple of dyno runs with the stock muffler removed from the stock header, and it was no where near as loud as just blipping the throttle with this pipe. It's even loud when shutting the throttle; it sounded a bit like the scene at the beginning of "The World's Fastest Indian" when Burt wakes up his neighbors. ;D
 

scottly:
As Chuck has raised the question of pipe size, I thought I should update this thread. ;)
I did try an XR 500 pipe, adapted to the FT, and found it caused a loss of both torque and HP compared to any combination of primary pipe lengths with an ID of 1.270". The XR pipe dyno run is 223, plotted in green.

Navigation

[0] Message Index

[*] Previous page