Undercarriage sound deadener ?

[cobrAA]

Hey guys,

I expect to go with a bigass exhaust and looking to keep it as quiet as possible ( weird isnt it? lol), have you heard of this coating ? http://www.summitracing.com/parts/liz-50115/overview/

Any other recommandation? I was recommanded to go with a helzmert (sp?) resonator but it look a big complicated to calculate, ( maybe frankiman could help me pull it out tho..)

Thanks!

[cobrAA]

por15 ?

http://www.por15.com/RUBBERIZED-UNDER-COATING/productinfo/RUCS/

[Skym]

Could use this stuff, as is heat resistant -

http://www.oppracing.com/category/484-thermotec-fire-retardant-sound-deadening-materials/

Best to use mufflers to keep exhaust quiet (coby where cat was, square muffler near rear wheels, big N1 rear exhaust). Just make sure mufflers are straight through and it shouldn't affect flow too much. Also position of mufflers in exhaust is critical, so copy factory exhaust (factory has worked it out).

[cobrAA]

Will do. I planned to use 3 items, 4 if needed. ( i.e: one resonator, 2 muffler). Never thought about the factory plan tho!

[Skym]

Factory plan is what I used on my car with 3" exhaust and is around 83.6DB when DB tested (DB limit should be 95DB in most countries). My cars exhaust has a fairly big N1 Hayama (made in Japan) rear muffler, square muffler near rear wheels, coby where cat was takes the drone out from under passenger side front seat. I get comments about how nice it sounds when driving past people and can make exhaust go silent by just varying throttle.

From what I understand, with sound, you have to look at the sound waves. As you already know, here's highs and lows in sound waves (in a pipe they are bouncing off the walls of pipe). You want the mufflers on the high's of wave to dissipate the sound wave (sound wave is hitting side of pipe).

So basically size of muffler (how much it dissipates the pressure / sound wave, bigger is better), placement of muffler (it is said that centre of muffler should be at 2/5, 4/5 of exhaust length, as where the high part of sound wave should be and should be where cat, square muffler are placed on factory exhaust system) quietens exhaust down. But from what I understand, bigger muffler affect's flow (slows exhaust gas down, but dissipates sound wave better), smaller muffler (coby) = opposite.

Also there's internal muffler design that plays a role (packing, size of holes in piping inside muffler and on cheap mufflers the packing can enter the muffler piping via the holes, I assume if holes are too big or there's not an extra layer inbetween pipe, packing a material). Some mufflers work better than others.

[Supraclean]

Por 15 is awesome stuff, id use that.