Forcefed Posted March 11, 2004 Report Share Posted March 11, 2004 O.K....maybe I did world that a little funny. But try this....it IS more than about backpressure...in a way. With the proper amount of backpressure you will maintain a critical amount of heat or pipe temperature. This temperature (which can be manipulated due to backpressure) is important to the return wave reaching the exhaust port in time. Here....read this.... The rpm band in which a pipe pumps maximum air into an engine depends on the speed of sound in the pipe, causing the suction and pressure waves to arrive at the exhaust port at the correct times. The speed of sound in a gas depends on its temperature. This makes sense because temperature is really just the average speed of the molecules whizzing around in the gas. The motion of any disturbance in the gas--a sound wave--is limited by that average molecular speed. Raising the gas temperature raises the average molecular speed, and the speed of sound rises with it. So a hotter pipe acts shorter than a colder pipe. At room temperature, the speed of sound in air is 1087 feet per second, but inside an exhaust pipe it is much faster--1500-1700 feet per second. As the exhaust port opens and the high-pressure pulse dumps into the header pipe, the pulse may initially move faster yet, perhaps 2600 fps. Whether intentionally or not, every pipe is designed for some internal gas temperature--that which existed during the development dyno runs. If in field operation the pipe somehow runs cooler than it did on the dyno or in field testing, the suction and pressure waves in the pipe will arrive at the exhaust port late. If the pipe runs hotter than intended, internal waves will arrive too soon. Either way, the engine will not run the way it should. That being said...I agree that stinger length and diameter are the most effective ways at manipulating this temperature (especially in drag pipes). But the world of in-frame pipes also have another variable (however minor it might be) and that is the silencer packing. Is it cutting hairs....maybe. But true! You got ot a little wrong there forcefed. Back pressure is the enemy. Really....??? Huh...... Quote Link to comment Share on other sites More sharing options...
Pjw350 Posted March 11, 2004 Report Share Posted March 11, 2004 Hey I seen a guy on ebay a while back selling Duct liner/insulation as silencer packing. Has anyone tried that. We normally have scraps layin around the shop. Quote Link to comment Share on other sites More sharing options...
FadedDreams Posted March 11, 2004 Report Share Posted March 11, 2004 That might have been the stuff i bought.When i took my silencers apart it was like a powder in there,I bet most of it got blown out.Really all that was left in there was the outside because it was held together by tape.I think this time i'm gonna spend the extra money to get the right packing. Quote Link to comment Share on other sites More sharing options...
909 Posted March 12, 2004 Report Share Posted March 12, 2004 Just as an FYI: The factory packing will not blow out but will become caked with oil just inside the perforated core of the muffler on most systems. This is especially true for the toomey, fmf, etc.... systems. If you use junk packing not designed for exhaust packing, it can turn to powder and blow out almost immediately. There are really 2 options, we sell the plain old glas packing everyone here is used to seeing and its gonna set you back $20 for a 450 gram bag. For some applications we sell the race tools repack kits. This has the same packing but is enclosed in a bag or "cartridge". To install it, you just remove the cartridge from the box, slip the core through the enter and put the can back together. Smoe shops carry this stuff and it does last a long time, better than plain packing for sure. Also, in dyno testing for our out of fame drag pipes, the pipes with a built in muffler made more horse power than the stingers on the same length pipe. We no longer make the stinger pipes, less power and more chances of another riding area being closed. Quote Link to comment Share on other sites More sharing options...
brugal Posted March 12, 2004 Report Share Posted March 12, 2004 So what are the other options "name brands" that can be used for packing? Im going to have to do mines... Quote Link to comment Share on other sites More sharing options...
909 Posted March 12, 2004 Report Share Posted March 12, 2004 The ones I have listed here for the cartridge is, pro circuit fmf power core 2, and bills. There may be others available now but this is all I show. You can always either buy the loose material or the packing sheets if yours is not listed. DMC has their own "rebuild kit" available too. All of the repacking materials we carry here are from RaceTools with the exception of the DMC kit. Quote Link to comment Share on other sites More sharing options...
frocashmoney24 Posted March 12, 2004 Report Share Posted March 12, 2004 yea about anyone that makes pipes makes silencer packing, i bouth some fmf for my dynport and just cut it down and put it in Quote Link to comment Share on other sites More sharing options...
brugal Posted March 12, 2004 Report Share Posted March 12, 2004 The ones I have listed here for the cartridge is, pro circuit fmf power core 2, and bills. There may be others available now but this is all I show. You can always either buy the loose material or the packing sheets if yours is not listed. DMC has their own "rebuild kit" available too. All of the repacking materials we carry here are from RaceTools with the exception of the DMC kit. THANKS!!!! Quote Link to comment Share on other sites More sharing options...
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