Although I'm not experienced with building helices to be specific periods, I think I have to agree with the above: to actually gain over the 11c/24 burn reaction, the amount of time spent burning must be very long relative to the lengths of the fuses.
However, I do believe there is room for improvement in helix design. By starting with a somewhat odd LWSS-on-MWSS flotilla I was able to find a helix edge component in a few different variations (low *WSS options on top, smaller area options below. Left-most is for comparison):
x = 188, y = 60, rule = B3/S23
I don't know if it's known, but I figure there's probably some other useful corner-turn reactions out there we don't know about yet. If it produced the same glider four gens earlier it would allow for a 4x 17c/45 helix, but since it doesn't, the maximum speed for a period 180 helix is only 3c/7...EDIT:
Interestingly, the Coe ship by itself can function as a helix edge. Not only that, but the glider ends up displaced over 20 cells at nearly lightspeed. Unfortunately the big plume created from the reaction prevents it from being all that useful:
x = 22, y = 10, rule = B3/S23