High flow mufflers?

speedracer · Post by **speedracer** » Sun Feb 19, 2006 7:11 pm

How much difference will one really make on a na car?

OB · Post by OB » Sun Feb 19, 2006 7:53 pm

Not a huge diff. More high end power and some say it could improve gas mileage. I like the look and sound of a quality straight-thru, so thats the main reason i got it. neons stock exhaust flows very well as it is, so not much power can be made by upgrading in an NA application.

Knoxville_R/T · Post by **Knoxville_R/T** » Sun Feb 19, 2006 8:17 pm

I think that the highest is something like 4 hp and 4 tq from the thermal. An exhaust on a neon is pretty much for sound untill you get into some bigger breathing mods and need that 2.5" exhaust.
-Brian

quicksilvr · Post by **quicksilvr** » Sun Feb 19, 2006 9:28 pm

With your mod list, you (speedracer) would see something like 5-7hp in the upper rpm's, maybe more, over a stock exhaust and muffler. But again, "high flow" could mean your current Vibrant, or just a 35" glasspack in the midpipe, with the entire rear section removed.

There's a diff there for sure....it'd be interested to know exactly what it turned out to be on a dyno, and where it would come to play.

Wisher2 · Post by **Wisher2** » Sun Feb 19, 2006 11:11 pm

It should make a little difference

Sparky828 · Post by **Sparky828** » Mon Feb 20, 2006 8:27 am

if your exhaust is really loud does that mean there is less restriction?

quicksilvr · Post by **quicksilvr** » Mon Feb 20, 2006 10:43 am

Sparky828 wrote:if your exhaust is really loud does that mean there is less restriction?

In many cases, yes. The things that absorb or cancel sound waves as they travel down the exhaust never help the exhaust systems ability to flow....sometimes they don't hurt very much, but sometimes they hurt alot. But don't hear my saying that every loud exhaust flows well.

An engine makes the most noise on it's power stroke...actually almost all of the noise you generally associate with "exhaust" sound comes from the stroke when a compustion event happens. With some complicated calculations, you can make a simple tube, of specific calculated length that you weld onto your tailpipe at a 90 degree angle (perpendicular to the tailpipe) and cancel out the frequency that is caused from the power stroke, but only at one set RPM. If you wanted to cancel it at a another, different RPM, you'd have to calculate a specific length and make a second tube. So, for example, if done correctly, at 3000 RPM +/- 3, your exhaust would drop up to 30 decibals. That's ALOT. This would be an example of a high flowing AND silent (at certain RPM) exhaust.

J8t4m · Post by **J8t4m** » Mon Feb 20, 2006 10:54 am

What is your current exhaust like ?

You would benefit slightly from a 2.25 exhaust system . . . .

If you already have a "Hi-flow" Vibrant exhaust- You might be better off getting a new Exhaust Manifold (ported to 2.25 or bigger) and geting a whole new system . . . .

but thats alot of time and money -
So whatever : )

speedracer · Post by **speedracer** » Mon Feb 20, 2006 12:34 pm

woops! What I meant to say was a high flow cat. Sorry, so anyway will a high flow cat make a difference.

quicksilvr · Post by **quicksilvr** » Mon Feb 20, 2006 12:52 pm

speedracer wrote:woops! What I meant to say was a high flow cat. Sorry, so anyway will a high flow cat make a difference.

, whoops is right....

The answer to that question, is no, hardly a difference at all. The only reason I can see for spending the money on a "high flow" cat to replace your stock cat is if you have changed your exhaust significantly enough to not be able to even use your stock one anymore. If you can't use your stock one, sure buy a high flow aftermarket. But if you just want to replace it for the sake of flow, you won't see/feel any gains. Reason being, a catalytic converter is still what it is....high flow or not, forcing the exhaust threw that honeycomb mass is restrictive, and if you want the cat to actually do it's job, there has to be enough of it that you won't see a difference in performance between high flow and stock. Even if it's like an advertised 50% flow increase, it's kind of the same as saying Miller Light has half the carbs of Bud Light........it's only the difference of 3 carbs.

speedracer · Post by **speedracer** » Mon Feb 20, 2006 12:54 pm

Very well put!

J8t4m · Post by **J8t4m** » Mon Feb 20, 2006 1:10 pm

LoL - Crack me up . . .

OB · Post by OB » Mon Feb 20, 2006 3:42 pm

im not disagreeing with quick, but i have heard that high flow cats, when installed with a highflow exhaust, could gain a few ponies. Having said that, a gain is much more likely to happen in a turbo app IMO. Keep in mind that an aftermarket cat is about as legal as not having one at all (in CA at least), so be careful with emissions if your state has strict rules. I believe a cat is required in EvERY state though, but im not sure about the rules on upgrading the stock one.

dblsg · Post by **dblsg** » Mon Feb 20, 2006 7:32 pm

^ true true, a lot of shops wont even replace the cat, unless its obviously messed up.

nght18 · Post by **nght18** » Mon Feb 20, 2006 8:10 pm

i have a magnaflow 2.50 axle back. Not sure if it made much power...but it sounds really nice and quite with the srt-4 mid pipe

nght18 · Post by **nght18** » Mon Feb 20, 2006 8:35 pm

hey dblsg.....did u get a change to run ya car on the track yet?>..if u did what u ran. and Ornageblast i live in FL and we have no emissions here so we can go cat less if we want. I'm gonna get the TTI long tube header. So i'm gonna see how the car runs without the cat. If i have too, i will get a high flow cat. Its funny,i had a 94 sentra SE-R with no cat and CEL didnt come on

OB · Post by OB » Tue Feb 21, 2006 5:46 pm

youre actually ALLOWED to run catless? i dont think thats 100% true bro. even if you dont have emission doesnt mean catless exhaust is legal. here in CA a visual AND chemical inspection is required to pass SMOG, but im sure that everywhere else if a cop found u with a catless exhaust he'd surely write you a ticket. then again, im not sure of any of this. why would ALL header/turbo back exhausts that delete the cat say "for off road use only" if it didnt apply to every state?

quicksilvr · Post by **quicksilvr** » Tue Feb 21, 2006 5:56 pm

In every state you are required to have a catalytic converter, ever since 1993, all cars and trucks have come with them from the factory. Most vehicle had them way back in 1975. You can get away without one if don't try to get your vehicle inspected without it. Or you know the person doing the inspection, and they let you off the hook.

I think what nght18 was saying was that since they have no chemical emissions to pass, same as me here in MO, it's easier to get away with it. Still though, a visual inspection is supposed to keep you from doing that.

OB · Post by OB » Tue Feb 21, 2006 6:12 pm

sounds about right to me thanks quick

DRO · Post by **DRO** » Tue Feb 21, 2006 7:08 pm

Where I live, backwoods Illinois, we don' have any kind of vehicle inspections so I could run whatever I wanted really

sullygully · Post by **sullygully** » Tue Feb 21, 2006 10:41 pm

^^ ditto, here in alberta, inspections are based soley on your insurance company. I bought a 86 bimmer, and didn't have to safety it.