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Can someone explain the logic of the HKS dual exhaust design?

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Old 10-17-2006, 12:27 AM
  #21  
leeboyNY
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Originally Posted by Tarek
At low rpm as the exhaust flow is relatively slower it is directed more to the upper chamber reducing the noise, while at high rpm high exhaust flow moves more into the rear muffler and out resulting in more noise. I think this design preserves torque at low rpm as there will be more pressure at low rpm due to the extra chamber, that is by-passed at higher rpm for more power. Just my opinion on the matter.
I agree with you.. Read the 3rd post.
Old 10-17-2006, 01:31 AM
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Silo
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With a 3" dual exhaust you should not be wondering about the deep sound and drone... the larger the piping diameter the more low frequency waves make it through it (unless you use something to equalize them). It takes large resonator/muffler volumes to cut them down again. In this case the HKS design is pretty good. You might want to compare the HKS HiPower Ti to the newer INJEN SES-TT... both are 60mm piping and very similar layout. However the INJEN has a pretty loud, very deep sound and has an annoyin drone at low to mid rpm range where as the HKS is the total opposite. How? By just adding these "dead chambers". If one was concerned he could use exhaust valves like similar to these to cut off the path at high rpm for virtualy no power loss (if there is any significant loss - something that you could proove by dynoing before adding the "dead chambers").
Old 10-17-2006, 07:48 AM
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97supratt
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HKS makes fine products, that chamber is used to quiet down the exhaust. If you don't like it, don't buy it.

On another note, if you want to quiet down your system add resonators. Resonators quiet down high pitch sounds in the exhaust whereas mufflers quiet down the low pitch sounds.

This is why I love my greddy evo2's so much, I have test pipes and they still sound relatively normal at low rpms but scream at high rpm's.
Old 10-17-2006, 07:50 AM
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97supratt
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Originally Posted by ISMSOLUTIONS
Technically the flow would increase and you would get more sound - and that sound is likely nothing you want to hear

HKS has done this for a reason - the sound of the exhaust is very 'rice' to begin with, so your likely to experience much more of that, lots of drone, and likely lots of popping, etc. as well.

Is the performance going to be better - maybe. Flow will increase, but that doesn't always transfer into performance increase.

Rick

Nothing is "ricey" about HKS.
Old 10-17-2006, 09:30 AM
  #25  
leeboyNY
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Originally Posted by Silo
With a 3" dual exhaust you should not be wondering about the deep sound and drone... the larger the piping diameter the more low frequency waves make it through it (unless you use something to equalize them). It takes large resonator/muffler volumes to cut them down again. In this case the HKS design is pretty good. You might want to compare the HKS HiPower Ti to the newer INJEN SES-TT... both are 60mm piping and very similar layout. However the INJEN has a pretty loud, very deep sound and has an annoyin drone at low to mid rpm range where as the HKS is the total opposite. How? By just adding these "dead chambers". If one was concerned he could use exhaust valves like similar to these to cut off the path at high rpm for virtualy no power loss (if there is any significant loss - something that you could proove by dynoing before adding the "dead chambers").
Yup my exhaust makes terrible drone at low to mid rpm. I'm going to mimick HKS design and we'll see what happens..
Old 10-17-2006, 08:04 PM
  #26  
ISMSOLUTIONS
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Originally Posted by 97supratt
Resonators quiet down high pitch sounds in the exhaust whereas mufflers quiet down the low pitch sounds.
Almost right...

Resonators are mostly exhaust tuning aids. They will filter high and low sounds - it depends on the resonator, size/length and amount of packing, if they are perforated core or spiral louvre. Some are 'bullet' style and some are 'can' style.

Resonators do their jobs in two ways:

1 - They filter sound via their packing (minimal) and

2 - They slow down the pulse enough (minimal) to shape the sound as well.

Both of the items above will affect high and low pitched sounds generated by the engine. Resonators are really fine-tuners in this category.

Mufflers do what resonators do, but at a much higher and more efficient level. They absorb and reflect pulses so shape sound, as well as flow of the exhaust.

When it comes down to it - they are all mufflers and resonators...

Rick
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