Catback Exhaust system
Lead Driver
Joined: Sep 2003
Posts: 7,013
Likes: 205
From: SoCal
I have to admit that whatever Ford did in designing the exhaust system, they really made it quiet. But since someone had to sit down and go through the laborious design process to accommodate the noise, efficiency, fit, and mass-producibility, why didn't they just take the extra step of making a less restrictive system?
An excellent example of a very well designed stock system is on the v8 Mustangs built between about 1985 through 1993. The exhaust system definitely has more of a rumble than most of their passenger cars, but they worked very well. I think one published spec shows a pressure drop of about 2" of water. In fact, most owners who replaced their cat-back systems (me included) found that the aftermarket systems made a lot more noise than power. The most annoying added noise was a "drone zone" at around 2000 rpm under load. The stock cat-back system worked well enough that no significant gains were to be had with aftermarket systems with a stock engine, and it was very quiet. In fact, even those (like me) who replaced the stock headers were not able to verify significant power gains on a dynamometer.
An excellent example of a very well designed stock system is on the v8 Mustangs built between about 1985 through 1993. The exhaust system definitely has more of a rumble than most of their passenger cars, but they worked very well. I think one published spec shows a pressure drop of about 2" of water. In fact, most owners who replaced their cat-back systems (me included) found that the aftermarket systems made a lot more noise than power. The most annoying added noise was a "drone zone" at around 2000 rpm under load. The stock cat-back system worked well enough that no significant gains were to be had with aftermarket systems with a stock engine, and it was very quiet. In fact, even those (like me) who replaced the stock headers were not able to verify significant power gains on a dynamometer.
New User
Joined: Jan 2003
Posts: 20
Likes: 0
From: Ottawa Canada
Originally Posted by Bear River
And unless you have money to throw away, don't do a performance system on either unless you have parts that are failing or near failing anyway.
Then the flex pipe broke at the flange. Again his fix was welding in a reducer to the flange and then the flex into the reducer. Imagine how small the pipe is now at the flange. This is "back woods Bubba fixin's" at it's finest (or worst).
Finally the back of the muffler is rotted out where the tailpipe goes in. In fact the tailpipe pulled right out of the muffler. The tailpipe is about all I could salvage from this mess.
The flexpipe, muffler and tailpipe were replaced in September 2003. I got the parts from my local NAPA store. Back then in Canadian $$$ the flex was $74.77, gasket - $3.09, muffler - $65.00, tailpipe - $16.50. I think over the years I was quoted around $250 to $350 for a "Y" pipe with cats. Then I suppose I should put in a new oxygen sensor too.
Looking at the rust on the front studs, I know they'll likely snap. The local muffler shop wants $150 to replace the studs if they snap. I think they quoted 1.5 hr labour to drill out the studs, tap the holes and install new studs.
The flex, muffler and tailpipe lasted just under 4 years and almost 100,000 km. All this is honestly more than the van is probably worth. I've got an arm's long list of things that need to be done as well. But on the other hand, I really want to see how long this van can last. So what do you recommend?
Wylde
'94 Aerostar (382,000 km and counting)
Lead Driver
Joined: Sep 2003
Posts: 7,013
Likes: 205
From: SoCal
If I were to keep a car with a long list of problems, I would try to find replacement parts from the salvage yards for as long as possible. However, I know that most scrap yards will not sell old catalytic converters, which are usually connected to Y or H pipes, so they will most probably have to be purchased new.
Posting Guru
Joined: Aug 2007
Posts: 1,036
Likes: 2
From: Portland, Oregon
Originally Posted by Bear River
I think 2.0L or 2.25" piping would be good. I think headers would be a great idea, but the biggest choke point is the y-pipe. We redesigned my parent exhaust system a few years ago and learned a few things. Yes it picked up power from the design on a new y-pipe, but it is running a single 3 way cat. This made it considerably louder, so I don't recommend messing with the cats, or if you do, replace them with 2 aftermarket converters. The y-pipe needs to be made from 2" pipe and needs to merge into a single 2" or 2.25" pipe on the 3.0L. This will at the very least require modification of the front converter, since it is about 1.75" stock. From the cat back, I recommend 2", and from the muffler back, go with 2.25". This overcomes the restriction from bends and from the partial collapse of bent pipe. This is also the ideal size for mounting exhaust tips, since most exhaust tips for small cars and trucks are 2.25" ID. On ours we went too large, with 2.25" from the y-pipe back. The result is a slight loss in low end torque. If I was to redo the system, I would have kept it 2" all the way to the muffler.
I also found the Magnaflow, is a big mistake on an Aerostar. It causes a horrible resonation and droning inside my parents 3.0L van, especially for these in the middle and back seats. We ended up having to put 2 mufflers in series to keep the droning in check, and it is still overly loud inside.
I have so far been impressed with the way this setup has made my 4.0L run and sound, but I definitely learned something from doing my parents. Keep the improvements modest, focus on the greatest choke points, and use quiet mufflers that do not resonate. The ideal pipe size for a 3.0L is 2.00" OD pipe, and the ideal size for a 4.0L is 2.25" OD pipe. Increasing the size slightly after the muffler will not adversely affect performance and will project the sound out the tailpipe better. The factory y-pipe on both models is poorly designed, the 4.0L can live with it, but the 3.0L is abysmal. And unless you have money to throw away, don't do a performance system on either unless you have parts that are failing or near failing anyway.
I also found the Magnaflow, is a big mistake on an Aerostar. It causes a horrible resonation and droning inside my parents 3.0L van, especially for these in the middle and back seats. We ended up having to put 2 mufflers in series to keep the droning in check, and it is still overly loud inside.
I have so far been impressed with the way this setup has made my 4.0L run and sound, but I definitely learned something from doing my parents. Keep the improvements modest, focus on the greatest choke points, and use quiet mufflers that do not resonate. The ideal pipe size for a 3.0L is 2.00" OD pipe, and the ideal size for a 4.0L is 2.25" OD pipe. Increasing the size slightly after the muffler will not adversely affect performance and will project the sound out the tailpipe better. The factory y-pipe on both models is poorly designed, the 4.0L can live with it, but the 3.0L is abysmal. And unless you have money to throw away, don't do a performance system on either unless you have parts that are failing or near failing anyway.
hmmmmmmmmm ok i see what your saying i ask because my van was purchased in 94 in indiana, and drivin in all kinds of weather there for six years before the previous family drove it to beaverton where it resided as a part time driver till now when i bought it... and incase people don't know... indiana salts their roades... so my piping is quite rusty, and the pipe that goes from muffler to behind the rear axle is lose (i can move it around with my foot) and is full of holes. so i do see myself replacing this current exhaust system by next summer for sure. i currently am not feeling like i am getting carbon monoxide poisoning, which is good (i know the symptoms, my friend had a header/downpipe "leak" (previous owner didn't install one of two gaskets) and we would get really sleepy and mad headaches all the time... so if i start to feel those symptoms i'm parking the van untill i can either borrow the money or save it up myself to get it done new. any thoughts? if i can i'm deff. using the 2" piping to the 2.25" piping for muffler back, and will deff. see if i can't fabricate some 2" headers for my aero... the only thing that bothers me/stumps me is the stupid forged header pieces vs. single pipes. oh well. thanks again Bear River.
Last edited by DCRB; Aug 18, 2007 at 04:23 AM.
Elder User
Joined: Dec 2006
Posts: 830
Likes: 0
From: Kitchener,Ontario,Canada
Originally Posted by Wylde1
Ok. Here's my situation on my '94 Aerostar with 382,000 km. The "Y" pipe seperated where it goes into the first cat. A friends quick fix was to weld a reducer into the cat and then weld the "Y" into the reducer. Why he didn't just put the "Y" back into the cat and weld that, is beyond me.
Then the flex pipe broke at the flange. Again his fix was welding in a reducer to the flange and then the flex into the reducer. Imagine how small the pipe is now at the flange. This is "back woods Bubba fixin's" at it's finest (or worst).
Finally the back of the muffler is rotted out where the tailpipe goes in. In fact the tailpipe pulled right out of the muffler. The tailpipe is about all I could salvage from this mess.
The flexpipe, muffler and tailpipe were replaced in September 2003. I got the parts from my local NAPA store. Back then in Canadian $$$ the flex was $74.77, gasket - $3.09, muffler - $65.00, tailpipe - $16.50. I think over the years I was quoted around $250 to $350 for a "Y" pipe with cats. Then I suppose I should put in a new oxygen sensor too.
Looking at the rust on the front studs, I know they'll likely snap. The local muffler shop wants $150 to replace the studs if they snap. I think they quoted 1.5 hr labour to drill out the studs, tap the holes and install new studs.
The flex, muffler and tailpipe lasted just under 4 years and almost 100,000 km. All this is honestly more than the van is probably worth. I've got an arm's long list of things that need to be done as well. But on the other hand, I really want to see how long this van can last. So what do you recommend?
Wylde
'94 Aerostar (382,000 km and counting)
Then the flex pipe broke at the flange. Again his fix was welding in a reducer to the flange and then the flex into the reducer. Imagine how small the pipe is now at the flange. This is "back woods Bubba fixin's" at it's finest (or worst).
Finally the back of the muffler is rotted out where the tailpipe goes in. In fact the tailpipe pulled right out of the muffler. The tailpipe is about all I could salvage from this mess.
The flexpipe, muffler and tailpipe were replaced in September 2003. I got the parts from my local NAPA store. Back then in Canadian $$$ the flex was $74.77, gasket - $3.09, muffler - $65.00, tailpipe - $16.50. I think over the years I was quoted around $250 to $350 for a "Y" pipe with cats. Then I suppose I should put in a new oxygen sensor too.
Looking at the rust on the front studs, I know they'll likely snap. The local muffler shop wants $150 to replace the studs if they snap. I think they quoted 1.5 hr labour to drill out the studs, tap the holes and install new studs.
The flex, muffler and tailpipe lasted just under 4 years and almost 100,000 km. All this is honestly more than the van is probably worth. I've got an arm's long list of things that need to be done as well. But on the other hand, I really want to see how long this van can last. So what do you recommend?
Wylde
'94 Aerostar (382,000 km and counting)
Thread Starter
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Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Well, I mentioned on a previous post, I think the best solution to fixing the y-pipe situation is to use a cat with dual inlets and an O2 between the arms. This way you get an accurate O2 reading, and it saves time and space. But the 4.0L has an oil filter right in the way. The best solution I can think of it to relocate the oil filter.
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Former ******
Joined: Nov 2004
Posts: 4,901
Likes: 2
From: Salt Lake City, Utah
Originally Posted by xlt4wd90
If I were to keep a car with a long list of problems, I would try to find replacement parts from the salvage yards for as long as possible. However, I know that most scrap yards will not sell old catalytic converters, which are usually connected to Y or H pipes, so they will most probably have to be purchased new.
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