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  #16  
Old 11-09-2002, 11:11 AM
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I used the flowaster 80 series camaro muffler. The only cats I own have tails and eat constantly. There is a sound file of it in my locker.
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  #17  
Old 11-09-2002, 11:58 AM
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Quote:
Originally posted by immortal_suby
I used the flowaster 80 series camaro muffler. The only cats I own have tails and eat constantly. There is a sound file of it in my locker.
Of the cats eating?
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  #18  
Old 11-10-2002, 04:40 PM
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Oky doky

Here's my plan. I'm gonna get some copper hi-temp sealer, and make sure there are no leaks around the gaskets. Then I'm gonna check the pipes and make sure there are no other leaks. Then I'm gonna check the flanges and make sure they're good. I know for a fact that one of my flanges isn't bolted to anything...so I'll bolt that. Then, when I have some money, I'll try to quiet the low end "fart" sound with some resonators. Anybody know where I can get the proper type of resonator. Do I want to put one in place of each cat I cut, or do I want just one farther down the pipe like the stock setup? I'd acutally like to somehow tune the exhaust so that the low end is almost non-audible...I just want a growl when I open it up. Any ideas?
Also, CE light is still coming on, but I have no clue why.
Finally, on a separate note, anybody know if the Sylvania Silver Star bulbs are any good. I would assume they are since Sylvania is a major brand.
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  #19  
Old 11-11-2002, 02:54 PM
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Resonance & Backpressure.

What is the resonator? What does it do? What is resonance?

What the hell are they talking about? And what’s that got to do with ‘back pressure’?

No four-stroke engine needs or uses backpressure. Defined as a residual ambient pressure in the header pipe.

The term ‘back pressure’ is erroneously used to describe the action of sound pressure waves that operate in the exhaust. These pressure waves start with the opening of the exhaust valve. This positive pressure travels down to the end of the pipe, where it is replaced with a negative wave that travels back up to the cylinder to reduce the pressure.

This pressure wave moves inderpendant of the gas flow, moving through the gas changing the pressure as it goes. It does not move the gas, it just changes the pressure in the gas.

It’s like when you drop a stone in a pond, the pressure waves travel out to the edge of the pond, to be reflected back to the centre. It does not move the water, it just changes the pressure and as water can not be compressed, it formes ripples on the surface.

Resonate waves may not seem to be all that important but it is this technology that has transformed the two stroke from a 50hp/lt. Weakling into a 400hp/lt. Superstar.

Subaru used this technology in both inlet and exhaust systems to design a very efficient engine. There is not much that you can do to increase the torque output, without resorting to No2 or forced induction.

Harvey.
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  #20  
Old 11-11-2002, 03:05 PM
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Re: Resonance & Backpressure.

Quote:
Originally posted by oab_au
No four-stroke engine needs or uses backpressure. Defined as a residual ambient pressure in the header pipe.

If that were the case, why do both Honda and Yamaha put valves in the exhaust of their top sportbikes? These valves close down at low engine rpm.

CJ
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  #21  
Old 11-11-2002, 03:16 PM
oab_au oab_au is offline
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Re: Re: Resonance & Backpressure.

Quote:
Originally posted by cjoffe


If that were the case, why do both Honda and Yamaha put valves in the exhaust of their top sportbikes? These valves close down at low engine rpm.

CJ
Is that 2-stroke or 4-stroke.?

Harvey.
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  #22  
Old 11-11-2002, 03:23 PM
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Both 4-stroke inline 4 cylinder bikes. Yamaha R1 and Honda 929. There may be more by now, but those are the two I know of. I know that if you replace the exhaust and remove the valve, you lose torque but gain top-end HP. I know that when I removed the cats on my 928, I lost torque but gained top-end (and noise!).

CJ
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  #23  
Old 11-11-2002, 04:09 PM
oab_au oab_au is offline
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Quote:
Originally posted by cjoffe
Both 4-stroke inline 4 cylinder bikes. Yamaha R1 and Honda 929. There may be more by now, but those are the two I know of. I know that if you replace the exhaust and remove the valve, you lose torque but gain top-end HP. I know that when I removed the cats on my 928, I lost torque but gained top-end (and noise!).

CJ
Don't. know mate, I will have a look see whats it's about.

It would not be the first time that they use some device to astound the oppersition. Remember the oval pistons, anti-dive front ends.

Harvey.
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  #24  
Old 11-11-2002, 04:47 PM
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Correct

You're right...backpressure isn't the right word...it's kinda getting tossed around too much here. What I'm asking about is the scavenging effect. If the gases have an area to expand at just the right location, then that expansion will create a vacuum and pull the following exhaust gases out. That's why I want to know if 2 resonators where the cats were would be best, or if one resonator in a stock-like location would be better...heck, would it be best to just cut the stock resonator off the stock pipe I kept and weld that into my new system in the same place it was stock? Now that I've asked, I don't really think there's anybody on the network with a degree in acoustics or waves or something of that sort, so I'm guessing it's gonna have to be experimental...unfortunately I don't have the $$ to experiment. I guess for now I'll keep the KC pipes and the straight through path where the cats were, and just hope that sealing and tightening bolts will solve my buzzing problem. This is, however, an interesting discussion, so please feel free to add to it.
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Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's STI...it will always be STi to me
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  #25  
Old 11-12-2002, 02:43 PM
oab_au oab_au is offline
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Exhaust pipe valve.

Quote:
Originally posted by cjoffe
Both 4-stroke inline 4 cylinder bikes. Yamaha R1 and Honda 929. There may be more by now, but those are the two I know of. I know that if you replace the exhaust and remove the valve, you lose torque but gain top-end HP. I know that when I removed the cats on my 928, I lost torque but gained top-end (and noise!).

CJ
Hi CJ, Had a look at them, It's basicly the old Yamaha EXUP system.

This type of valve is mainly to help with the rideabilty of the bike, Not to increase the torque output of the engine.

These engines are designed to put out max torque at 7000 to 8000, so they have a few holes in the torque curve down around 2500 to 3500. They use a restrictor valve in the exhaust and the Honda's is also linked to a flap in the air box, to increase the velocity of the gas flow at these low rpm and to prevent inlet spillage due to the cam timing.

The SVX is 'mindmannered' compared to these engines, so we dont have that problem, yet.

Harvey.
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  #26  
Old 11-12-2002, 03:05 PM
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Re: Correct

Quote:
Originally posted by SVX10
You're right...backpressure isn't the right word...it's kinda getting tossed around too much here. What I'm asking about is the scavenging effect. If the gases have an area to expand at just the right location, then that expansion will create a vacuum and pull the following exhaust gases out. That's why I want to know if 2 resonators where the cats were would be best, or if one resonator in a stock-like location would be better...heck, would it be best to just cut the stock resonator off the stock pipe I kept and weld that into my new system in the same place it was stock? Now that I've asked, I don't really think there's anybody on the network with a degree in acoustics or waves or something of that sort, so I'm guessing it's gonna have to be experimental...unfortunately I don't have the $$ to experiment. I guess for now I'll keep the KC pipes and the straight through path where the cats were, and just hope that sealing and tightening bolts will solve my buzzing problem. This is, however, an interesting discussion, so please feel free to add to it.
Don't put 2 resonators where the cats were, as they will move the point of resonance up beyond the rev range of the engine.

Put a chamber in the standard position. It does not have to be a
SVX one, most modern cars have one, so any is better than none, bigger is better though as I said before it needs to be well built to withstand the battering the sound waves will give it otherwise the smooth sections will reverberate and make more noise.
Go to the muffler shop see what they have, that will fit.

Harvey.
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  #27  
Old 11-12-2002, 03:33 PM
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Bigger is better?

Is that just up to a certain point? I looked under a 350Z today at work, and it's got a tiny resonator, maybe 1ft long, 6" wide, and 3-5" deep. It seems like if bigger is better, there would be much larger resonators on cars. I'm assuming I'll go to an exhaust shop and they'll have certain ones for certain types of engines(dispacement, cylinders, those types of criteria). Otherwise I may just wait a few weeks and use the one from my stock exhaust (since it WAS designed for the SVX).
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Time for my very own long list of mods:
92 SVX LS-L - Ebony Pearl - 2002 WRX 5MT trans w/STi gearset (rebuilt & installed myself ) - BMW E46 HID retrofit - Kenwood Headunit - Phoenix Gold 75x4 RMS amp - Alpine Type R 6.5" front components - Alpine Type R 6x9 3way rear speakers - 18"x9" Rota G-Force wheels w/225/40ZR18 Toyo T1R's - Mychailo's custom springs - Urethane front & rear sway bar bushings - KC exhaust (2.5" dual magnaflow) - Escaine seat swap - Removed Spoiler

I don't care if Subaru says it's STI...it will always be STi to me
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  #28  
Old 11-12-2002, 03:41 PM
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<< Go to the muffler shop see what they have, that will fit.>>

Good luck with that. I printed one of Harvey's posts regarding resonators and took it to a couple of "performance" exhaust shops, and they didn't have a clue as to what he was talking about.

Hey Harvey, can we persuade you to open up an exhaust shop here in the states?
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  #29  
Old 11-12-2002, 04:28 PM
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Quote:
Originally posted by elninoalex
<< Go to the muffler shop see what they have, that will fit.>>

Good luck with that. I printed one of Harvey's posts regarding resonators and took it to a couple of "performance" exhaust shops, and they didn't have a clue as to what he was talking about.

Hey Harvey, can we persuade you to open up an exhaust shop here in the states?
Most exhaust men, would make good plumbers. Unfortunately they look at the exhaust as water piping and not as a collection of pressure pulses.

Open an exhaust shop? sorry. Done my time at the bench. Lead a life of leisure now.

Harvey.
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