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3 restos WIP = psycho
 
kenikh's Avatar
 
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Was talking to a mechanic buddy about these last night:

Quiet HORSEPOWER

The older Phase 9 and new Phase 10 apparently measure zero backpressure and make a decent effort at quieting cars down. Might be worth a peek,
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Old 05-12-2010, 06:40 PM
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Not to get off the subject Juan, what is that where your bumper bellow is suposed to be???
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Old 05-12-2010, 07:18 PM
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He has an air scoop there to direct some air towards the turbo.

For a more subtle flush look and better aerodynamics you could glass in a naca duct in the quarter extension in front of the origonal bellows to do the same thing.
Old 05-12-2010, 07:42 PM
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There are people her making 500rwhp with 3 inch pipes (DonE).

I think you are fine with 3 inch and a cat/premuffler bypass into a factory C2 turbo second muffler is a hard combination to beat from what I have heard.

I have seen some writings that may indicate that 3.5 inch might be getting on the edge close to that but I think that is for longer run pipes.
Old 05-12-2010, 07:58 PM
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I really like that car!
Old 05-12-2010, 08:02 PM
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Cool plane too....
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Old 05-12-2010, 08:46 PM
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Quote:
Originally Posted by 911st View Post
I thought you had a special build muffler?

Brian here makes 930 mufflers. He might be able to make somthing that is not as loud if you check with him.

Monty stands out in my mind.

I suspect the stock euro / non cat muffler is not as bad as most might think. One could add a second tail pipe out the other side and cap it for street runing.

You might be able to add a secondary muffler in your the left rear fender and loope your's throught it. Then you could remove it and reinstall you pressent tail pipe for having fun. Just a thought.

I need to upload the pictures of the monty We just rebuilt for one of our customers. The internals are garbage in the turbo application with 2.250 tubing every where and mild steel to boot. As soon as I can figure out how to download them from my phone I will post.
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Old 05-13-2010, 05:06 AM
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I cut open what I thought was an early B&B (pretty sure). Same thing. It only had a 2.5" passage inside.

Put on Borla straight through muffler and picked up an instant 30hp on the dyno.

Monty is supposed to be one of the best so that is a heart breaker.

Last edited by 911st; 05-13-2010 at 06:58 AM..
Old 05-13-2010, 06:54 AM
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Here's a few more pics of my 3-1/2" straight through muffler:





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Old 05-13-2010, 08:59 AM
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That is friggen gorgeous.

I understand the transition out of the turbo is very important so as to keep there from being any unnecessary turbulence right where is can effect the turbo the most.

Only thing I might wish for is a way to make for a longer radius single curve to the tip.

Again, very well done!!!
Old 05-13-2010, 02:51 PM
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Quote:
Originally Posted by 911st View Post
That is friggen gorgeous.

I understand the transition out of the turbo is very important so as to keep there from being any unnecessary turbulence right where is can effect the turbo the most.

Only thing I might wish for is a way to make for a longer radius single curve to the tip.

Again, very well done!!!
Thanks!

I figure the extra bend at the end helps knock off a little noise and the big ID should help reduce any power loss.

Maybe someone could make one for sale (Brian?). Unfortunately, knowing what I spent on material alone I bet it would be at least $2K.


BTW, I have an old dual out B&B if anyone's interested.
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Old 05-13-2010, 05:55 PM
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Quote:
Maybe someone could make one for sale (Brian?). Unfortunately, knowing what I spent on material alone I bet it would be at least $2K.
I'm glad you mensioned cost. Most folks are not familiar with the expense of good materials. 3" 321 is several dolars an inch with no bends. I priced out a set of headers in Inconel and was quoted $5000 in raw materials alone. That is before you bend a pipe or strike a torch. God help you if a mistake is made during production!

You have a great design there and we are getting ready for the 3rd generation of my muffler which will look similar to what you have. What I have seen, for the typical 375whp 930, is that bends make no significant difference if the ID is large enough to minimize back pressure. The 180 bend we make has a larger ID than the pipes leading to and from it.

I don't know how quiet Juan's car needs to be but a setup like you have would work very well in his application.
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Old 05-13-2010, 06:30 PM
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Very nice craftsmanship there David.

I like your muffler support bracket that is incorporated into the flange. Very nice touch.

What filler rod are you using on the 321 stainless and do you back purge?
Old 05-13-2010, 06:47 PM
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It's 304; I figured after the turbo didn't require 321.

I only weld if there's no one else available , so a guy at work helped me. He didn't use a purge gas since all the welds were accessible, but obviously you'd have to on headers.

Here's a shot my exhaust bracket (pardon my falling off heat shield ). I didn't put any real engineering into it, but my thought was I wanted it to flex with expansion and cornering but but be stiff over bumps. The material is 410SS so it's stronger than a 300 series.



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Old 05-13-2010, 07:17 PM
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I like it!

Simple and effective.

I just noticed that it appears you machined a shoulder in the flange for the pipe.

Excellent attention to detail. I was thinking about making my own flange and if you don't mind; I'll probably steal that idea.
Old 05-13-2010, 07:37 PM
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In principle turns add turbulence and a tight turns magnify this. A 180 deg turn adds turbulence as the gasses have different length paths to follow. This adds drag and back pressure. I belive a tight 90 can add .25 psi of back pressure in some cases.

Same thing for going up a size in pipe. If it is not a proper transition the gasses have to slow down to fast, turbulence is created and back pressure added. If you then add a reduction back down it again it adds even more turbulence and back pressure.

The better bend is a 'flattened' pipe of the same net cross section volume as the feeder and exit.

This can be evedenced when looking at most new intake manifolds where the intake runners look like flat tubes. The makes for a lesser variation in path distances around a bend which reduces turbulence potential and drag so better cylinder filling is had.

The need to make such a sharp turn might be a small part of the reason Porsche went to a chambered muffler but it was probably mostly for the durability and ability to control sound. If in fact a tight 180 has to be done, it might be a less restrictive to accomplish this with a chambered design.

With a chambered muffler it might be possible to creat an environment just inside the can that is a low pressure area. This way the high pressure coming from the turbine can escape quicker to a much lower pressure area.

On a system such as on a 930 where the muffler is right at the turbo this could be a significant plus and potental increase turbo response. The key being to have ways for the pressure to easily escape said can or environment. If this can be accomplished, it might be possible for the turbo to act like more like it is just attached to a short exhaust pipe to atmospher.

Still, we can brake the rules and still see a major improvement over stock and some times over what we think is a better design. Of course, a perfect exhaust for one build may not be perfect for another build and a perfict build has a cost.

We can get into trouble sometimes trying to think ourselves through a design. What we think might or might not work and what dose is not alwas the same. It is not untill it hits the dyno or the track that we know if we have been successful.

Just my two cents and not worth a penny more.
Old 05-13-2010, 08:00 PM
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Quote:
Originally Posted by nocarrier View Post
Very nice craftsmanship there David.

I like your muffler support bracket that is incorporated into the flange. Very nice touch.

What filler rod are you using on the 321 stainless and do you back purge?
347 is the filler of choice for 321 and you should back purge it before the turbo not required after though nice
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Old 05-14-2010, 04:10 AM
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This is becoming more complicated than choosing a clutch! well not really that was a nightmare!

At the moment, the first problem that I see is that I will have to make the new muffler to come out of the right side versus the left side, this to avoid a 90 deg turn, not a big deal I guess, but I like to have it on the left to monitor the flames my existing muffler as you can see has the connection and exhaust piece flanges together so there are no bends......what to do what to do



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Last edited by juan ruiz; 05-14-2010 at 04:55 AM..
Old 05-14-2010, 04:50 AM
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Quote:
Originally Posted by juan ruiz View Post
This is becoming more complicated than choosing a clutch! well not really that was a nightmare!

At the moment, the first problem that I see is that I will have to make the new muffler to come out of the right side versus the left side, this to avoid a 90 deg turn, not a big deal I guess, but I like to have it on the left to monitor the flames my existing muffler as you can see has the connection and exhaust piece flanges together so there are no bends......what to do what to do



Jaun you should call brian and see if he is willing to do some sort of sponsership on a unit
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Old 05-14-2010, 04:56 AM
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Chambered is not an option. Any turbo book you can find will verify that. A few bends are not going to make a significant difference if they are designed properly.
THE question is how quiet does the muffler have to be?
One option is to copy my modular system and use a large ID muffler like david in conjunction with a removable 180 and tailpipe. You can then simply remove the 180 and tailpipe and pop on a stubby tailpipe. This will allow the use of diffusers or other additional sound deadening devices on the removable portion of the system.
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Old 05-14-2010, 05:16 AM
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