thanks mr kerry

been wondering for a long time how it actually went together. so then a ?? for you, in the case of the air movement--more in, needs more out, would a true straight system work with some sort of forced air induction system??

here in canada, they don't worry too much about epa as far as i know, the vehicle will only need inspection if changing province or reconstruction after an accident. the boys get upset if its too loud and your stepping on it...but not an emissions thing.


to 03fx4

i think borla has a website with some sounds...good luck

 

Thanks man, with all that being said, very well stated i might add, in not going to get rid of my cats, im just looking for a muffler to deepen the tone of my exhuast. So any thoughts on a good muffler? Thanks again.

 

Well I left a few points of the workings out to simplify it a bit... the piston travel also has something to do with the air getting drawn in and the exhaust going out - okay it's the major portion - but you want all that exhaust out, right? With a high volume/low velocity adaptation like opening up the cats, the scavenging effect will suffer so you peak numbers will be higher in the rpms and your performance may actually drop off some. The rumble is good, I won't discount that.

The removal of down stream restrictions is where many of the aftermarket muffler set ups get their peak numbers.

I have removed other restrictive exhaust parts myself... take a look at my gallery in the last 3 custom exhaust pics... that's the factory 'y' pipe. It is going to be a far greater restriction than the cats. It could be that many people confuse taking out the cats while getting rid of that 'Y' as being the reason for a perfromance improvement.

As far as a power adder and open pipes go... it's up to you and a professional tuner to get the power out of the application. Looking at aftermarket shorty headers, I see they've upped the size by an 1/8" in the primaries, but the collectors remain at 2 1/2" - so I'd at least keep the pipe at 2 1/2." If you go for more boost than say 9-12psi... a larger exhasut set up from the head out (custom headers) maybe in order.

We have a few gurus that hang out in the supercharger/turbo/nitrous forum further down the forum home page. Stop in and ask.

As far as the muffler... I have no personal tales about any exhaust outside of Bassani and the Summit brand name stuff... my Bassani is a custom setup using the in front of tire exit supercharged Harley kit from '02-'03. Very throaty, as the muffler is over 2 ft long.

-Kerry

 

Kerry, your message made good sense and you seem to have some expertise in exhaust. Question for you. You noted that the front O2's make the change in the air fuel mixture. I was told that the fronts make changed thru the PCM and the backs monitor. Right? My issue was that I had a horrible idle when the system warmed up and was told by the stealership that my O2 sensors (new Bosch) needed to be changed and that my cats were probably partially plugged. They said that one bank read 3-4psi and the other ran 7-8 PSI which should run 1-2 PSI according to them. I have since bought magnaflow direct fit cats and hope to fix the idle prob. Does all that sound right? Thanks, Bamadoc

 

Im sorry, but I have to disagree with you on that one. I ran a straight pipe (hacked off muffler) for a little over 6 months. I just had my Flowmaster Super 40 installed on tuesday...and it gave me all my torque back, and then some! I can cruise up the hill by my house without the truck shifting into 2nd now.



03FX4_ncguy: I love the sound of my Super 40. Very deep sound...but it would be much nicer without the cats (and I need to fix the multiple exhaust leaks on my truck). If you still want louder/deeper...then try a set of Flowmaster race mufflers...10-series I think

 

bamadoc - I'm by know means an exhaust expert... however I think you should check out this link about your "clogged" cats: http://www.misterfixit.com/cat.htm
The first O2 sensors monitor A/F the last O2 sensors monitors if your cats are operating correctly.

ATC Crazy - You have found out about flow tuning. You decreased your flow volume (amount) by installing an obstruction. Ever see those mufflers on cars and trucks with the baffles that you can change? They look like a cap over the exhaust. You can call it back pressure if you want, but you actually affected the exhaust flow velocity by installing the restriction that a muffler provides - again similar to putting you finger over a hose. You put the truck closer to the point that the exhaust going out is balancing the air/fuel going in.

 

Atc crazy, thanks for the heads up about the race series flowmaster. Does your truck sound like a mustang now? I wish i could here a sound clip comparing the 2 mufflers. The super 40 ( 2 chamber) and the 30 series (single) chamber race muffler.

 

I actually had one of thoes mufflers on my fourwheeler: http://img.photobucket.com/albums/v2...an-exhaust.jpg

It seems to me that exhaust flow velocity and backpressure are one in the same. The lower the velocity, the higher the air pressure (i.e. backpressure) is inside the exhaust pipe, and visa-versa.

 

Back pressure, when referring to engine operation, is the pressure caused by the reflective wave in a 2 stroke. This pressure wave is created by an expansion pipe (those odd ball shaped exhaust pipes you see on 2-stroke cycles are a good examples of an expansion pipe). The reflective wave is what keeps the intake charge in the head and prevents it from being drawn out with exhaust. You see, the 2 stroke has an issue since it only has two strokes... the exhaust gets put out on the power stroke, as the intake charge comes in... the fuel/air mix starts to go out as well. It's that tuned back pressure (reflective wave from the expansion pipe) that pushes the fuel/air mix back into the head just before the piston or valve gets closed and the spark goes off.

4 Cycles are more about cam timing when it comes to keeping the fuel/air mix in the head.

You don't need a back pressure or reflective wave with a 4 stroke, you can think you're talking about back pressure, but if you actually had a reflective wave it wouldn't do that much good. You want the exhaust to go the opposite way to keep your scavenging going. Exhaust doesn't do so well flowing the wrong way in a 4 stroke.

As far as changing velocity and calling it a pressure... ummmm...I know what you're trying to say, I just thought I'd point out what it really is. Don't get me wrong, there is a pressure in the tail pipe, it's just not pushing back up to the head... that's why they call back pressure... back pressure.

Hope I didn't loose you.

-Kerry

 

What?----Well then man QUIT SCREWING AROUND!! Add emissions legal headers first, then go to your local muffler shop and bore the ***** out of the pipes from the cats back---3-3.5 inch and add Borlas or something other than a glass pack for a DEEP sound. Make em sound like a monster truck!!

 

I put Gibson shorty headers and cat-back dual exhaust on my 2003 F-150 4.6L. It has a good sound. Not loud until you gas it. Everyone has Flowmaster, so I wanted to be different. Flowmaster all sounds the same to me. Doesn't impress me anymore. If money is no object, get the MagnaFlow header-back system. The high flow OBD-II cats must improve flow and sound. Looks like it only fits 5.4L, but I would think it would fit 4.6L. If it does, I may get it for my truck in a couple of years.

 

Sorry I didnt see this sooner NCGUY

The only time it sounds like a Mustang is on start up, before the RPM's drop to idle. My truck still has the stock cats on it, and I only have the SI/DO muffler. If I ditch the cats and make it a true dual set-up...then it would probably sound identical, if not very close to a mustang.

 

Also...another very, very loud muffler (assuming you run without cats) are the Goerlich mufflers. The Xlerator series if I remember right. A friend of mine is running them on a 3" true dual set-up on a mildly built 350...and let me tell ya...when he gets on it, everyone in a 3 mile radius will hear him (dont ask me how I know about the 3-mile thing *LOL*)