Building a New Exhaust

After looking at what's out there, I've decided to build my own system. The first step was to go out and buy a Magnaflow muffler (stainless steel). Next step is to take it to a shop and have them manufacture a 1 5/8 " merged header system (next week). Hopefully, they will be able to curve the merge to one side so it won't be seen from the back. The Magnaflow will be located between the value covers and the rear tire (vertical and hidden) and the exhaust will exit on the other side of the car. Heater boxes are still up in the air. If I can't buy a set, I may build my own (I have a welder and a torch). I'm hoping to end up with a hidden, merged 1 5/8 " system with heaterboxes and a very loud exhaust. My 911 shrould makes one hell of a lot of noise, so I want to be able to hear the exhaust when I 'step on it'.
Stay tuned
Ron

Ron, Happy new year!
on building your system, in K. Seume's exchange book there is some interesting information to consider if you haven't, on the length of the primaries from the head to their merging. ' 36" primaries will perform best between 2500rpm & 5500 rpm while 28" will work most effectively between 6000 rpm & 10000rpm.' He also talks of the diameter of the pipes. Have not seen much info on the physics of exhaust systems if you find out more in you prodject please share.

Ron, sounds like it's going to be a cool system. Something close to what I built. You'll love the sound of the Magnaflow. I finally got some pics of my system, will try to post today.

Thanks Victor and Eddie. Happy New Year! I was looking at my Magnaflow and it really is a beautiful piece. It's really quite compact; 14 " long, 4 1/2 " wide and 9 " high, with a 2 " wide diameter pipe. I test fit it yesterday and there will be no problem mounting it, vertically, beside my value cover/heater box. I will have to make provisions to take the muffler off for value adjustments. I'll definitely go with the shorter primaries, as I want the 'low end' and I won't be taking the motor over 6 grand. The important thing, to me, is that I won't see the muffler hanging out the back. I'd like to see those pics.
Ron

Ron I think if you want to optimize the low end <6000 rpm, then go with the longer primaries 36" lengths, sorry if I didn't make that clear. The lower the rpm the longer it takes for the next cylinder to fire and more time is needed to reach the merged section. As that exhaust reaches the merged point it should create a vaccum pulling on the next cylinders exhaust resulting in a more efficient flow and less back pressure. Then with higher rpms, cylinders fire faster which requires the merger to be closer to the heads to create the vaccum. I like your ideas on tucking the muff out of sight, and am thinking on taking that step too. Want to try to figure out how to have the single exhaust pipe leaving from the center rear in a big oval tube and not appear too convoluted.

(Message Edited 1/2/2003 3:25:54 AM)

Be careful with a custom built merged exhaust system, especially if you try to merge it to one side as the primary tube lengths may be out of whack with collector diameter/entry and curves may become so small they add restriction. This can cause a loss of horsepower, strange harmonics, and possible intake mixture inversion.

Before you leap, buy the book "The Scientific Design of Exhaust Systems" (I think that's the name, I gave mine away years ago).

Thanks for the input. I am going to move slowly on this project, since I don't have the funds to get it done again. I would like to have my exhaust exit the back too, like the Boxster and Boxster S.

My Magnaflow is mounted to the right of center under the valance, leaving access to the valve cover clear. Tail pipe curves back down and around to exit low right like a 911.

I have a similar setup to George... merged 1 5/8" header that curves right to the muffler and exits to the side. When the files come back online, there is a photo of it there... I will also try to post one of it later on my personal website (www.coltonperry.com) under the gear section.

George, I have seen pictures of your exhaust system, when it was posted on the other 'now defunct' forum. Unfortunately, my memory is a bit hazy on what it looked like. Did your merge come straight back, or did it curve? I know that the newer IMs have more room between the motor and the back valance. I'd love to see how your system fit.
Ron

Thanks colton. I'll check your site.
Ron

Ron, I posted the photo. If you need something clearer, let me know.

Thanks again, Colton. What type of muffler are you running?
If you want to see a very nice exhaust system go to www.intermeccanica.com/gallery_4_3.html
The car looks a lot like George's car, but this one has a tan colored top, while I think George's car has a blue top (could be wrong, though). This is the way I'd like my new exhaust system to look.

Actually, my car is the silver convertible "D" with beige top on the Intermeccanica web site photo gallery, but it's a 3/4 left front view so you can't see the exhaust.

You can see the pipe from the rear where it curves up and to the right from the mounting flange to the muffler; the Magnaflow muffler is totally hidden.

The dual muffler system on the Intermeccanica we site has to have the mufflers removed to set the valves.

I won't decide the location of the muffler until we put the car up on the hoist, fit the headers and then see where the muffler will fit. Near the back apron is, of course, the best location, but I'm not sure if my Magnaflow will fit back there (hidden). It would be nice, then I wouldn't have to drop it to adjust the values.
Ron

I'm going to look at some merged 1 5/8" headers tomorrow. The shop has three for me to look at; Bugpack, S&S (I think) and Kymco. I'm seriously thinking of building my own 1 5/8" heater boxes, since I can't get my car into the fabricating shop for a few weeks.
Ron

Ron, I finally posted the pictures I've been promising on the members file at carumba356. It uses a Kymco 1 1/2 in. header and heater boxes out threw duel Magnaflow mufflers. I think it gives a good compromise between performance and traditional looks. There's 2 pictures one mounted, one unmounted.

Eddie, just checked out the exhaust pics and have to say I am impressed. I am sure this came in much lower, dollar wise, than the set up I put on last month.

Now, as I understand it, this was Kymco's merged 1.5" with heater boxes for a Thing? And the dual exhaust/muffler set up... was that Kymco too? Cost? Thanks in advance.

Jim



(Message Edited 1/3/2003 11:22:44 PM)

Eddie, I also caught the pic of your dead pedal... love that! What pedal arm did you use, and how was it attached?

Jim
OKC

Your exhaust system looks GREAT. How about some details.
Ron

Eddie,
Wow. This appears to be what I (and everybody else) is after. Please give us all the details. Do you have 1-1/2" heater boxes also? Are the boxes also ceramic coated? Did the whole thing come from Kymco? We're all dying to know...

Thanks guys, for the positive input. The header is a 1 1/2 in. Thing header by Kymco as are the heater boxes. the two Magnaflow mufflers are 4in. x 14in. with 2in. straight threw center tubes, at about 85$ each. A nice feature of the Kymco heater boxes is they come already flanged.

The Kymco header and boxes sells for about 349$ raw. My local muffler ordered the mufflers and several mandrel bent tubes. We started by installing the heater boxes and header that takes you to the three bolt flange. Then I used the Y tube that came from the VS system. It is 1 5/8in. I cut off everething except about 3in. on each side. I'm told that these Y tubes are sold at most VW shops. we bolted the Y tube up then fabbed the tail pipes from 1 3/4 in. mandrel bent tubing. The only bend thats not mandrel bent is the first bend after the Y tube connection.

The dimple is on the inside of the bend so it's not visible. The tubing costs were 70$. the labor was 125$. Jeff at Kymco gave me a good deal to ceramic coat everthing. So what you end up with is 1 1/2in. header and boxes that go to 1 5/8in. at the flange, then 1 3/4in. just out of the flange all the way to the muffler then 2in. threw and out to the tips. It sounds nice and low with that distinctive duel throat growel. Like a car with more than 4 cylinders. The power difference was quite noticeable from the 1 3/8in. system that I had. I even tried just a stinger with a baffel for a weekend drive, instead of the muffler system to see if I could tell a difference. I could, the engine revs much better with the mufflers system installed.

Eddie, what size motor are you running in your car? What are the heads and size of valves? I'm just trying to figure out if I should go with a 1 5/8 " or 1 1/2". Mine's a 2110 with an 110 cam and 044 heads, with 40 & 35 valves and 40 Webers. Next year I plan to get the heads ported and move up to 44 or 48 Webers, so I thought that the 1 5/8 " might be the way to go. Any thoughts from the group?
Ron

Hi Ron, I wrestled with that same question. I now have a 1776cc built by Strictly VW in LA. Demello counter weighted crank, 12lb flywheel, VW heads w/ 40x35.5 valves ported as far as we could go w/o welding by Chong. 8 to 1 comp. ratio, 110 cam, 44 IDF's set up by Art Thraen. Buuut I'm kinda thinking about a 2272 in the future. In which case I'd need to go with a 1 5/8in. system. I've heard that going too big for the engine can cause bigtime low end power loss. LOL.

Oops, I ment a 2275cc. Sorry

Jim ,thanks for the kind words. The dead pedal was made from a VW clutch pedal. I cut it to length, and then with a razor knife carefuly cut the carpet in an L shape where I wanted it to go. then used stainles 1/4in. pop rivets and JB Weld and attached the pedal to the side of the pan rail. Then fold over and glue the carpet back. Not too hard, but it matches the rest.

I bought a 1 5/8 " merged header today. A Bugpack header. Very thick flanges and heavy tubing, which is good, since we will be altering it. I'm going to stay with my original plan of a single Magnaflow, even though I think Eddie's system looks sweet. Hopefully, I'll have my 1 5/8 " heater boxes built in a few weeks.
Ron

OH no, now I'm thinking TURBO! Saw a sweet little pull through system on another site. Maybe I'll forget the dual 48's and get a single 40 or 44 side draft and go turbo. I should put the extra cooling of my 911 shroud to good use...shouldn't I?
I've got to stay away from these high performance VW shops!

Ron, sounds like your exhaust system is going to be great. With 1 5/8in. boxes you should be set. If they turn out like I think they will you could probably take orders. good luck, and don't forget pictures.

Hey Jim, your new exhaust system sounds great. I almost bought one too. Any chance of some pictures? Thanks

Eddie, can you get in there to adjust those valves?

Took an old heater box apart...boy, there's a lot of fins in there! No wonder they're so heavy. Next step, fabricating the J tubes, since they don't drop down far enough.
Ron

Jack, haven't tried to yet. But I will probably have to. Three bolts at the flange and two at the supports, no problem. I'd rather drop the muffler than try to play octapussy. (oops wrong movie).

Ron, I talked to Jeff at Kymco today. He's been working on 1 5/8in. boxes for a while. Price has been the only hurdle. Are you taking orders yet? (just kidding), LOL.

I think one of the problems is that the pipes for a merged system do not run in the same line as heater boxes. They swing more under the push rod tubes. Then it becomes a nightmare trying to line up the new holes at the end of the heater box with the end of the header. My plan is to have the 1 5/8" tubes come out in the same location as the 1 3/8 " tubes and then have the merged headers modified to line up with the heater boxes. This could be a challenge, because the heater boxes are fairly long, so my fabricator will have to do some magic with those headers. (of course, this is where Murphy's law come into play...if something can go wrong..it will).
Ron

Ron, one of the problems I thought of with a true merged header, which may not be a problem for you, is the end of the collector hangs too far out the back of the car to make it look "classic". I know the flow is a little better with the long collector. That's the reason I opted for the Thing header. I guess it's just one of those trade offs that everybody's got to deal with. Any thoughts?

You're absolutely right, Eddie. The merged header will probably stick out too far. My plan is to cut it back a bit (1" or so), so that it does not stick out too far. I'd like to cut it back to a 2" opening, since my Magnaflow's pipe is 2" wide. I won't know for sure how much I will have to wait until my fabricator puts the headers on the car. It's going in tomorrow and hopefully he can help me with my heater boxes too, since my welding skills are limited. My brazing skills are okay, though(A before O or up you go). I realize I'll lose some of the qualities of a merged header when I cut it back, but I figure an inch or so won't make that much of a difference. Too bad I can't get to hear what your exhaust sounds like, Eddie. In fact, I've never heard a dual muffler set-up on a air cooled motor. I want mine loud, to drown out the noise from the 911 fan and the honk from the 40 Webers.
Ron