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Muffler Tech


Truenotch

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Pretty sure it was because you could jam a fist fill of swarf or steelo pads in em and bolt the plates back on to pass a wof then fish it all back out minutes after. I remember my sisters boyfriend raiding under our kitchen sink for pot scourers back in the 90s to pass a warrant.

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My old Buick i removed the cherry bombs. Now run straight pipes. Sounds way better and gets a warrant. The guys at the shop figure thats how they came originally back in 1952 so dont need them - just like it dosnt need seat belts.

 

Seen exhaust splitters on TradeMe. like the idea for my new 49 project. these legal in NZ? Like the idea of having both exhaust with mufflers out the back and when i want  to be louder  out the side pipes with no mufflers. Just seems like something that wont be legal even though its on TM

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By page 10 I was semi fired up and ready to have a fairly fiery rant at the lot of you (including those for whom I have some respect!), but then I hit 11 and Roman's excellent post where he mentions the previously unmentioned: LENGTH. Length matters.

 

Nice little tables, too, Roman! Good work. Pop that into a little JavaScript web app and give it three sliders: length, diameter, power. Animate it with a line graph and some colour and /thread. Well /thread for what it's become, which is about 25% muffler and 75% chanting 3", 3", 3" with mjrstar quietly making sense amongst it.

 

Pages 12 and up skipped. :-P

 

Before reading through this I'd already planned these:

  • KP60 blacktop = 2.25, 2.5 if I get excited, but probably not. Factory is 2 with restrictive mufflers and cat.
  • Ute 2.0 DOHC Holset = 3 (~2.5m short and overkill, 18" resonator, oval straight through, tolerable noise level and smooth sound, but I'll add one more muffler to it at some point)
  • Volvo 2.3 DOHC maxed td05hr16g = 2.5 (cruiser, max power not a priority, borderline sizing)
  • Volvo 2.3 DOHC Holset 3 (cruise and drag race, transmission will limit power before 3" does)
  • RB30DET with Holset HX52W 3 and choked by it, but I won't care...

One of the above exists, the rest are wet dreams that I'm steadily working towards... though I have most of the parts :-)

 

Datapoint: factory KLZE 2.5 V6 @ 7000 RPM = 200ps = 2.125 or so with many mufflers and no sound 2.5 would be better. I see someone asking about this at the tail end of page 11. I wonder what answer he got. Spolier: 3".

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The answer to every question in this thread about exhaust sizing.

 

Funny you should say that. This race car that runs my ECU:

(with flat shift, paddle shift, 2 step, blended load, engine dyno tune, etc)

 

Failed tech inspection on "too loud" and the in-the-field solution was to put a flat plate out in front of the exit which shaved off quite a few DB at least in the direction of the test equipment and got them through to the next stage.

 

Perhaps 3" with supertrap is the answer, though I think a 3" mild steel exhaust would have weighed about the same as half of that car. :-)

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They sound like underwater farts...  / they aren't really mufflers.

They are hollow tubes with a perforated tube up the middle and fibreglass stuffed between the perforated inner tube and the outer tube.

 

With your Morrie I would say it's fairly safe to say it won't be raucous though.

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They sound like underwater farts...  / they aren't really mufflers.

They are hollow tubes with a perforated tube up the middle and fibreglass stuffed between the perforated inner tube and the outer tube.

 

With your Morrie I would say it's fairly safe to say it won't be raucous though.

I had one on a Mini many moons ago (998cc with 58 hp at the wheels), gave basically a straight pipe from the extractors down the middle of the car.  Sounded sweet and not too quiet nor too loud. :thumbleft:

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i have a 1 1/2" from the manifold to tip, with a coby resonator after the diff

its cool, but not so cool when it sounds like its doing a mile a minute at 10kph. so want soemthing to go back under the passenger seat. problem is i cant afford to lose any hp at all haha

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i have a 1 1/2" from the manifold to tip, with a coby resonator after the diff

its cool, but not so cool when it sounds like its doing a mile a minute at 10kph. so want something to go back under the passenger seat. problem is i cant afford to lose any hp at all haha

How long a muffler can you fit there?  A 1 1/2" x 16" Coby could be quite effective, in conjunction with your existing resonator http://www.woottons.co.nz/product/small-super-coby-ssc-16/

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