Quiet Freeflowing Exhausts - No such thing?

[solitaire]

Hi There,

I have done a search on "exhausts" and "exhaust noise" in tech questions and checked the first two pages of results.

My Question is: Is it possible to make a free flowing exhaust that gives good power and is quiet?

I am looking at a 2.25" system for my na levin, I was thinking an adrenalin r muffler with two resonators. I have no idea what this will do. Do more resonators = quieter car?

My current exhaust is way too loud, I would like it to be quiet AND efficient/powerfull - is this possible? Have any of you got any products you recomend?

Thanks

Dave

[QikStarlie]

reso's will only quieten it down so much. i'd go big reso up front, then biggest baffled muffler (not straight through) that you can find at the back. bigger the chamber area, will generally make it quieter. to keep the flow up over size the muffler a few sizes. if your running 2.5" pipe run 3 in muffler, as you usual 2.5 inch muffler wont flow anywhere near a bit of 2.5" pipe. also running a length of pipe after the muffler will make it quieter. not muffler then big shinny tip or dumping straight out.

issues will be room and weight..


also smaller pipe diameter doesn't necessarily mean quieter

[Dell'Orto]

Easily done, but you need to spend coin. I believe Adrenaline R make their mufflers and can custom build? Could be a good way to go.

[strx7]

after building a number of big bore systems for various vehicles i have owned. i have concluded that the biggest factor in exhuast noise is length of pipe after the first distrubance (cat/muffler/resonator) and muffler design has alot to do with how much it quietens down. On our supra for example, i built some headers for it, 6 into 2, the secondaries run for quite a length and are 47/48mm diam. they then merge into 2.5 inch pipe go through 1 small rectangle muffler (just infront of diff) which has inlet and outlet on the same side and you can see straight thru, it then goes along a bit more into a 350mm round muffler (straight thru again) and exits with a tip of approx 20cm long 2.5 inch. it is quiet as, at idle from the front of the car it is barely audible, driving incar at cruising speeds it is very quiet, and up the revs it sings a nice tune incar, but outside you cant really hear it that well. fart cannons with oversized tips will always act as a megaphone. companies like rage/coby/chase all have a large range of mufflers in various shapes, sizes, pipe sizes and configurations, at good prices, they last a long time and are NZ made. I would suggest looking at them.

[RomanV]

Yeah, its always seemed odd that people have a hernia over making sure they have mandrel bends, but then looking at the muffler design... The gas has to navigate through a labrynth of horrible tight turns through the muffler itself.

[BZG Wagon]

I don't know much on the subject of exhausts; but I recall my friend playing around with different resonators on his GTR Skyline, and eventually managed to quieten it right down while keeping the same sized piping and flow the virtually the same.

The logic being the resonator uses sound waves fired at each other at certian frequencies to cancel the sound out, so it should be possible to have a quiet car at low & mid RPM, and loud at high RPM when you wouldn't care about it anyway (different sound frequencies).

I'd take what I just said with a grain of salt though - it's all based on old & vague conversations. Someone might be able to comment if it's on the right track.

[ch4ng]

This is a difficult thing to explain with words, and even with videos eg: youtube

My suggestion would be to find someone that has a similar setup in their car and start from there.

I have a Blacktop Levin with 4-1 extractors, 2.5" crush bent pipe, with 1 20? inch long resonator and a 2.5" superturbo muffler. I'm in West/Central Auckland, you're welcome to come check it out/ go for a drive to see how it compares to what you want out of yours.

[captain crescent]

If you aim the exhaust outlet /tip at the ground it makes a lot of difference. I have just fitted a Lukey Ultraflow in my Runx race car (2 1/2') and just one small 10 inch coby and its very quiet with the tip aimed at ground.

[BlakeNZ]

i have found resonators are rubbish at noise reduction, and make the car drone at low revs/ light throttle. My next car will have two mufflers, one at the rear, and one in the middle where a resonator would normally be. Large volume mufflers are certainly best for noise reduction.

[Lurkin]

hmm came to a similar problem with my old trueno (it was na too).

Found resonators were good for taking high pitch sounds that occured when removing cats and replacing with straight pipe - needs some form of muffler early on.

However it did little to actually reduce the volume of sound - it only really altered the pitch.

My plan was to use a offset 2.25" muffler, so rather than the noise going directly through the muffler, it would have to travel to the other side. This follows the wave node/ anti node idea discussed earlier. (It had a straight through muffler, not a fart cannon, on it when I bought it, and it did nothing to reduce the din it made. At 99 odd db it was eventually pain + illegal)

Alternatively I considered gutting factory mufflers... after cutting one open it was a total fail. there is way to much tiny sized internal piping/ spot welds to hold it together to do it easily with good results.

Lastly I thought that if offset muffler was unsuccessful I could attempt to cut it open and repack it with fibreglass.

These plans were far too much of a pita and I sold the car instead.

[lorolla24]

What do people think about the mufflers with the silencer you put up the end? I've been thinking of buying one.

Doe's the silencer make a big difference?
Doe's it compromise flow with turbo engines? How Much?

[touge_ae101]

silencer you put on the end is a waste of time. you restrict the flow heaps. known of guys who feel a very noticable drop in power with silencer in.

best free flowing and quiet exhaust resonators i have found is the standard ae101 straight through resonator. they are 2.25inch and do heaps of quietening. took my exhaust from earsplittingly loud to almost legal noise.
my exhaust consists of 2x old coby resonators (actually do almost nothing) and a straight pipe out the rear so the 101 resonator really does a good job!

[iOnic]

Removable silencers are illegal anyway.

[solitaire]

i've got a silencer in at the moment, only so when i start the engine im not deaf... no idea how i tolerated that noise level for so many years, its rediculous...

need to sort exhaust before wof really

[lorolla24]

Yeah, just thought it would be the easy way for long road trips to shut it up.

Just been looking at the flowmaster type mufflers. There for v8's but should work alright on my 4 pot.

Anybody have one on there turbo toyotas?

[iOnic]

I've put one on the Mrs' Starlet. 4EFTE/T04E/3" DP into 2.5" straight pipe (no mufflers and completely straight aside from the downpipe). Was rowdy as $&#$% so I cut a section out of the exhaust right at the back and welded in an offset 2.5" in/out Flowmaster and it's shut it right up. Doesn't even get a second look from the law enforcement fraternity. Road noise at 100km/h is louder than the exhaust ever gets.

[solitaire]

iOnic can you explain what you mean by offset? Sorry i should have asked this earlier...

[iOnic]

as opposed to straight through where the inlet and outlet are in line with each other

[solitaire]

as opposed to straight through where the inlet and outlet are in line with each other

Oh that simple... feel a bit silly now

thanks mate

[iOnic]

No worries I'm building an exhaust for my MR2 and after seeing (hearing?) the effect that it had on my partner's car I'm definitely going to use one or two. Butt dyno says performance wasn't harmed and it seemed to pull better down low.