I have a 1990 Acura Integra RS. I have a Ractive exhasut on it and a short ram intake… I plan on putting an aftermarket header on my car and a cold air intake… I was talking to a guy about taking off my catalytic converter and putting a down pipe on and he said that it wasnt a good Idea b/c I would loose a lot of back pressure which would take away a lot of my torque causing me to be slower off the line… He said that it would give me more RPM’s to play with but that without that torque off the line it wouldnt be much good… Does anybody have anything else to say about all of this?? any help would be nice… Thanx.
Retain your catalytic.
im running a test pipe… i love it…why do you want low end anyway?? when your racing… your always in the higher RPMs… just be careful cuz after you put a straight pipe… yoru exhaust is gonna get loud…and its gonna buzz… i changed my universal can out for a greddy SP
Why would you want low end? Jesus, I dont even have to answer this one. Plz retain your cat. :squint:
ok well i ran a test pipe for track use only… and had my cat for everyday use… it was WAY to restrictive on the top… so explain to me why do i want low end? besides… everyone has their prefrences
i think before we starting posting out of our butt-dynos as to whats faster/better, we should read these articles written by Tuan(SHO) aka Michael Delaney from team-integra.net, hes a very knowledgable person and could probably learn so much from him.
http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=2
http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=47
http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=48
http://www.team-integra.net/sections/articles/showArticle.asp?ArticleID=355
you might have to register to read them, but its worth it.
heres a little(actually pretty damn long) excpert from Michael’s article.
"B. SOME EXHAUST MYTHS TO DEBUNK FROM BEGINNERS
- Myth 1: The Obsession Over Exhaust Sound Quality: “What Makes A Good Sounding Exhaust?” AND “It Sounds Loud. So It Must Make a Lot of Power!”
quote:
The Exhaust Noise is the most common sound source of engine noises, and is usually 10 to 15dB higher than the overall noise level of the engine. The exhaust is of high temperature (800 to l000¡æ) and high pressure (3 to 4 barometric pressures). The exhaust process is divided into two stages: free exhaust and forced exhaust. The exhaust gas spews out of the exhaust valve and enters into the muffler along the exhaust manifold before draining into the atmosphere from the tail pipe. This process yields wide band exhaust noise.
The exhaust noise contains complex noise elements, including the exhaust noise with a base frequency measured in the number of exhausts in unit time, the resonance noise of the gas column in the pipe, the gas stream blowing noise at the exhaust manifold, the exhaust gas jetting and impact noise, the Helmholtz resonance noise of the cylinder, the Karman eddy noise and the turbulent noise inside the exhaust system.
Key factors deciding the exhaust noise of the engine includes the cylinder pressure, the exhaust valve diameter, the discharge capacity of the engine and the opening characteristic of the exhaust valve. For one same engine, the rotation speed and the loading of the engine are among the most key factors that contribute to the exhaust noise.
Loudness does not equate to power gain…loudness AND SOUND QUALITY depends on these:
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muffler length and size (volume or displacement: a larger can will be quieter),
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having a resonator pipe (no resonator means coffee can and loud),
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length of the resonator pipe (longer is quieter),
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the type of sound absorption material in the muffler (glasspacks suck, they melt),
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whether the pipe inside the muffler has louvers or holes (holes are quieter),
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exhaust tip size/length (big tip is louder) ,
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the exhaust’s design (3 types, as described above).
So when you shop around, compare and ask about these features that affect sound quality. The more features, the better the sound.
A straight-through design with a resonator, or a chambered design, or a twin-pass design are quieter than a straight-through design without a silencer cone or resonator. Having no resonator ensures a coffee cam sound. Straight-through resonators that have the same ID as the rest of the exhaust tubing is better for performance. The number of passes through the muffler, like in the quieter 2-pass Mugen or Hy-Tech exhausts, determine how quiet an exhaust is.
If you want a non-coffee can quiet throaty sound, look for the exhaust design characteristics I have listed above..a longer muffler and having a resonator are good starting points. Power depends on how the exhaust works with the header collector size and catalytic converter size, to help maintain a high exhaust gas velocity compared to the amount of fresh air you are dumping into the engine…most experts agree that the exhaust flow should be at least 70-85% of the intake flow (if it’s more than this…even better). So for exhausts as related to power?:
remember, please pay attention to diameter, diameter, diameter that will suit your hp goal.
A big newbie misconception: My exhaust is loud so it must be great!
- Myth 2: Big huge diameter tips are better.
You design the tip size to fascilitate where you want the bulk of your power to be along the rpm band. Bigger tips tend to push the peak hp up but at some cost to lower rpm power. Changing tip size affects the pitch of the exhaust note. Bigger tips have a lower tone. Don’t make the exhaust tip, even a resonated one, your focus of attention. It plays a minimal role in your system’s performance gains.
- Myth 3: I Need A Little Bit of Backpressure For Midrange Power
THE MIGHTY BACKPRESSURE MYTH:
You want zero backpressure not some backpressure as you may sometimes hear from a salesman or an oldtimer domestic V8 hot rodder.
Stock backpressure is around 16 psi in a GSR. Good aftermarket exhausts yield 2-5 psi backpressure. “Bolt-ons only” engine packages, in the past, used exhausts with some backpressure, since there is this incorrect belief that having a little backpressure prevents the fresh air/fuel from shooting into the header at cam overlap (when both the opening intake valve & the closing exhaust valve are simultaneously, partially open). The backpressure supposedly “pushed” the fresh air/fuel back into the combustion chamber rather than having it go into the header. This shooting of fresh air/fuel from the intake manifold and intake port into the header cannot happen at cam overlap, since the pressure inside the header is already much higher than on the intake side , even when there is zero backpressure.
In reality, having more backpressure reduces the difference between the higher pressure in the head’s exhaust port and lower pressure in the header and cat. You need this difference in pressure going from the head to the exhaust system or “pressure gradient” to keep the exhaust flow speed or energy at a high level. Having some backpressure during cam overlap and the exhaust stroke means that the exhaust gas must now push against something and therefore, this backwards force slows exhaust gas down.
This need for backpressure no longer exists when you have a properly tuned (timed) engine and a good stepped header. In fact, increased backpressure may lead to backwards flow or “reversion”, where the exhaust gas travels backwards into the combustion chamber and dilutes the fresh intake charge at cam overlap. At the very least, it slows exhaust flow velocity or energy and prevents the creation of a vacuum for scavenging.
So please ignore the obsolete “you should have at least some backpressure” sales pitch. It’s all about the creating high exhaust flow velocity/speed or energy leaving the exhaust port, in order for the header-cat-exhaust SYSTEM to do it’s job properly (i.e. remove all the burnt exhaust gases and help pull in fresh intake charge by scavenging at cam overlap) and make power for you.
all this info is credited to Michael Delaney over team-integra.net, it is not my info, so gotta give credit where credit is deserved.
I tryed it
i have a gutted cat and have to say i noticed an awsome increase in power however my fuel is running rich due to my O2 sensor:bowdown: