I wont mention the name of the person who suggested this because this persons name often makes people get pissy and i want this thread to be about discussing whether or not this thoery is valid without any bias based on who claimed it.

anyhow, a well known engine builder and all around automotive smart guy said that if you take a long piece of pvc piping and dimple the inside of it that it makes a muffler that is very quiet and flows incredibly well. allow me to elaborate.

basically, if your exhaust is 3in, you take a 3in piece of pvc pipe (or whatever the closest size available is, as to avoid causing the flow to diverge at all) and you use a dremel tool to make evenly spaced dimples that are round and approximately 3 to 5mm deep, down along the insides of the pipe. it ends up being like an inside out golfball. you then build a canister with teh appropriate gaskets and so forth and mount the pvc lined pipe up to you exhaust.

he stated that the dimples do little to effect the flow yet they have a substantial impact on the sound.

now i know that some lexus came with a dimpled underbody and that helped to cut down on turbulence which cut down on wind noise.

what do you think? does this sound like bullshit?

 

If you ever get to see deep inside the intake of an F16, on the floor you'll notice dimples.

A certain car guy, a certain engine builder, worked for General Dynamics....just so happens to be who makes the F16.

That person used it on his car painted black, and it apparently sounded and looked very "sleeper". Sounds like something to do just for the hell of it. If anyone triggers on, and in turn mentions this persons name, then whether it works or not doesn't matter. H-T can be gay like that.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by RC000E &raquo;</TD></TR><TR><TD CLASS="quote">If you ever get to see deep inside the intake of an F16, on the floor you'll notice dimples.

A certain car guy, a certain engine builder, worked for General Dynamics....just so happens to be who makes the F16.

That person used it on his car painted black, and it apparently sounded and looked very "sleeper". Sounds like something to do just for the hell of it. If anyone triggers on, and in turn mentions this persons name, then whether it works or not doesn't matter. H-T can be gay like that.</TD></TR></TABLE>

i dont know if we're talking about the same guy. but yes, honda-tech hates him for some reason.

so do you think it will work? lol.

i would be willing to try it on my car but i havnt got a welder.

 

i don't know what will do more for sound deadening, the dimples or the density of the pvc.

I wouldn't run plastic on my exhaust system even as a muffler, aluminum is one thing, but plastic?

if i were to try this i'd use a piece of thicker aluminum, but even then, i'd think you'd have to make the dimpled section quite long in order for it to make any difference what so ever in the sound characteristics. If that's the case, how are you going to get enough uniformly shaped dimples in a long tube?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cua0 &raquo;</TD></TR><TR><TD CLASS="quote">i don't know what will do more for sound deadening, the dimples or the density of the pvc.

I wouldn't run plastic on my exhaust system even as a muffler, aluminum is one thing, but plastic?

if i were to try this i'd use a piece of thicker aluminum, but even then, i'd think you'd have to make the dimpled section quite long in order for it to make any difference what so ever in the sound characteristics. If that's the case, how are you going to get enough uniformly shaped dimples in a long tube?
</TD></TR></TABLE>

supposedly the guy who cooked this up has done it before and the pvc section needs to be a couple feet long.

also, i would bet my left nut that the pvc wont get anywhere close to melting if its back where the muffler should be.

 

that guy also used the PVC as the tip, after the muffler.

And yes, the dimples do make a difference in the noise coming out of the pipe.

 

Does this guy have a diagram? Or possibly and example picture?

My mufflers totally shot...meaning 4" slot on the side so when I replace it this weekend I'll test this & post results if anyone is interested.

 

Well, this "guy" contributed a sh*t load of his time, and was VERY free with his knowledge to the DIY community, but ended up shutting himself down as far as the internet goes. All his old information and what not is no longer accessible despite many requests by myself and a few others.

There aren't many that'll give and give and give like he does/did, and in typical H-T fashion everyone beat the guy into the ground over his hp claims. Some guy that's been making power and breaking "mainstream" molds for decades certainly has no reason to lie about anything.

Anyway, I'll go on a tangent easily, because I miss the info and the crowd that lingered around him. All that's gone now though...so.

I'd try it....the pvc pipe thing. I can assure you that the pvc isn't going to melt that far down the system. Someone should bring this to fruition and do some audio. If I didn't have so much on my plate I'd do it for sure.

 

If i were to attempt this I wouldn't use regular PVC I would use CPVC more commonly known as Blaze master its good up to 1400*F and is easily attainable at a plumbing wholesaler

 

The guy who came up with this setup didn't use any type of special product...he used plain pvc...and he ran it for years making some serious power. Someone just build it

 

Theres gotta be an easier way to do it than drilling hundreds of little dimples inside of a pipe somehow. How about getting a peice of tubing a 1/4" bigger diameter than your exhaust with stepdowns on each end to match it up with the rest of the exhaust, then cut out a rectangle peice of sheetmetal the same length and width to fit around the contour of the inside of the pipe, and take it to a machine shop and somehow get them to "roll" it on a machine that wil put similar dimples in it and shove it in there and tack the ends. Then you have the same thing and is all metal and a lot easier right?

I went all out and spend $30 on a resonator for my exhaust though

 

The theory is sound (hehe). Look at a sound proof room with the big spikes on the wall .... same premise. An old trick for sound proofing a basement/whatever was to line the walls/ceiling with those cardboard egg cartons.

As for the fabrication of it, I don't know if I'd bother with the pvc. I forget the melting point of pvc but it would be safe to use near the back of the car, I just think it would be a pain in the *** to make all the dimples. I would just get a peice of sheet, a bolt, a hammer and a piece of wood. Round the tip of the bolt and then just run along smacking it with the hammer to make your dimples. Once you have your dimples you just roll it up, weld the seam and install. Using mild steel would be cheap and you could make some decently deep dimples.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by levelzero &raquo;</TD></TR><TR><TD CLASS="quote">I would just get a peice of sheet, a bolt, a hammer and a piece of wood. Round the tip of the bolt and then just run along smacking it with the hammer to make your dimples</TD></TR></TABLE>

or just use a big ball peen hammer

 

I thought about a ball peen hammer, but in theory you would want lots of small dimples which means a small hammer. I'd rather user a 5lb sledge and let the weight of the hammer do the work Plus I personally wouldn't be very accurate if I was just swinging a hammer, at least with the bolt I can put the dimples were I want.

You could use a pick of some sort too, like the ones used to break off the flux from stick welding.

 

Pvc huh. Im gonna give this a try.

 

i think it would be easier to make it from metal, but isn't the density of the metal one of the contributing factors of how the exhaust sounds? in other words, if its made of pvc, then wouldn't it absorb more sound than metal?

also, let me see if i can make this make sense, how much of the exhaust note is from a pulse or soundwave that exits cleanly without bouncing around inside, and how much of the exhaust note is the byproduct of the sound wave bouncing off of the various bends?

see where i am going with this?

i have a decent understanding of fluids and how they move due to pressure and all of that. what i dont understand very well is the relationship of those fluids and the sound that they generate.

i would guess that most of the sound that we hear out of the tailpipe has been refelcted off of some portion of the interior of the exhaust system and therefore making the exhaust system of a material that would absorb some of this sound might be a good thing.

hell, why stop at pvc piping? i have an oven mit thats made from silicon rubber and i can stick it directly on my exhaust manifold without melting it. why dont i just line my exhaust pipe with that stuff?


again i dont have any real education regarding sound (its actually something that i really need to look in to, as its been puzzling me for years) but i can make observations.

one really obvious observation is that with a factory plastic intake, you hardly hear the intake at all. slap a metal intake on there and its louder than hell. so i would say that the plastic absorbs or deadens the sound considerably more than metal.




Modified by Mr.E.G. at 2:50 PM 4/25/2007

 

come on people. these questions arnt answering themselves.

 

I'm having a hard time visualizing the dimples. Show a picture and I will test it out. I'm currently building and exhaust system for a buddy. This is a perfect time to test this out.

 

I remember a HUGE thread about this on his old forum.

If you can't quite visualize this, think about a golf ball. You want to make "dimples" about the size of a nickle if I remember right inside of the PVC tube, about 1" apart.

So, if you took a golf ball, took the skin off and made it flat. Then enlarge it so the holes are about the size of a nickle and make a tube out of it. that is the look that you are going for.

I don't know if I explained that quite right, but I think it is close. Please correct me if I got the size wrong. I DEFINATLY remember the spacing should be about an inch, and you don't want straight lines.


On another note, I miss that forum. Still keep in touch with a few of the guys from there like LFP.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by godofcheese &raquo;</TD></TR><TR><TD CLASS="quote">I remember a HUGE thread about this on his old forum.

If you can't quite visualize this, think about a golf ball. You want to make "dimples" about the size of a nickle if I remember right inside of the PVC tube, about 1" apart.

So, if you took a golf ball, took the skin off and made it flat. Then enlarge it so the holes are about the size of a nickle and make a tube out of it. that is the look that you are going for.

I don't know if I explained that quite right, but I think it is close. Please correct me if I got the size wrong. I DEFINATLY remember the spacing should be about an inch, and you don't want straight lines.


On another note, I miss that forum. Still keep in touch with a few of the guys from there like LFP.</TD></TR></TABLE>

i remember the dimples being smaller. maybe im wrong though, its been a while.

you're right about the spaces and all of that, or at least thats how i remember it as well.

also, RC000E and i were just talking about LFP. whats he up to? i assume its something rediculous and involves revving to eleventeen thousand rpms

 

i just thought of something. i want to try this but i dont have a welder. ... but what if i go ahead and fabricate the pvc part and just hold it up to exit of my exit (which is just straight pipe anyway)? if it works at all then i should be able to tell a difference just by making it sit flush with the exhaust pipe opening, right?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.E.G. &raquo;</TD></TR><TR><TD CLASS="quote">i just thought of something. i want to try this but i dont have a welder. ... but what if i go ahead and fabricate the pvc part and just hold it up to exit of my exit (which is just straight pipe anyway)? if it works at all then i should be able to tell a difference just by making it sit flush with the exhaust pipe opening, right?</TD></TR></TABLE>

Good idea. You could even add in a few bends to replicate as closely as posible the exhaust going over the rear susp to get an even better comparison.

 

wait- how the hell are you supposed to get the dimples inside of the pvc pipe, especially if its 2 or 3 feet long?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TurboCoop &raquo;</TD></TR><TR><TD CLASS="quote">wait- how the hell are you supposed to get the dimples inside of the pvc pipe, especially if its 2 or 3 feet long?</TD></TR></TABLE>

im skinny and i have a dremel tool snake attachment.

 

It is quite possible that the dimples should be smaller. I want to think that he got mad and said "try it out and see yourselves what works".

Latest project from LFP other then his plasma ignition system was shoving a s2k engine into a 510. Pretty stock looking suprisingly enough. (he is also going to college, and i think that is the most suprising)