I just had a cat-back system installed. My factory flex had broken, and the muffler was starting to rust, so I just had them do everything behind the cats. The cats themselves were fine, and I can see no justifiable reason for replacing them. They are not the performance bottleneck, and the vehicle sounds wrong without them anyway. High flow converters are about the same rating CFM wise, and the motor cannot possibly meet the OEM CFM rating anyway.

The factory pipe at the cats is 2.25". but instead of using a 2.25" flange Ford opted to use 2" 2 bolt flanges to save money (they use these same flanges on many other vehicles and Ford gets a good discount on them for volume purchasing). So they reduce the pipe to meet the flange size and bring it out 2" the rest of the exhaust system (this also allows them to use 2" mufflers that they buy in bulk). This is a poor design and was made for cost reasons, rather than performance or fuel economy reasons. So I used one of my 2.25" flexes and eliminated the flange there and welded directly to the OEM converter outlet pipe. We then brought 2.25" pipe over to a Full Blown 3052 muffler, which is comparable to a FM 50 series. It is built differently inside however. This was selected, because while it is a performance muffler, it has a nice sound without being overly loud. In fact it is not much louder than the factory muffler. and much quieter than a broken flex pipe.

We opted for a 2.5" pipe behind the muffler, mostly because bending pipe collapses it, and resists exhaust flow through it. By making it larger, we compensate. The pipe sizing behind the muffler is not as critical as it is in front, since gases have already mostly smoothed out inside the muffler case anyway. As far as retaining the factory bottom end torque, remember, the exhaust system is a nice 2.25" in front of the muffler, which is a suitable size for a 4.0L. This size keeps the exhaust velocity at the ideal level at low RPM without being overly restrictive at high RPMs. It is the factory size on some other Ford models.

The tailpipe ends in a very complimentary exhaust tip that of all our product selection, just seems to match this vehicle better than anything else. It adds some of that bling that is otherwise missing and gives the whole job a finished look. This system was installed yesterday, and I put over 500 miles on it since then. I like the results, noticeable power increase across the entire powerband, without any of the throttle lag common with overly large systems. It is nice and mellow sounding inside when cruising, but when I mash the throttle, it lets everyone around know this beast means business. It moves out smoothly and responsively, matching the sound coming from the tailpipe.

I will try to get a sound clip soon if I can.

 

Interesting. I had always assumed that an exhaust upgrade was a waste of time and money. I do like that exhaust tip!

 

Do you have access to mandrels for your tube bender? They are supposed to keep the pipes from collapsing when you bend them. The trade off is the large radius side gets thinner.

 

nice job...someone is good with a MIG wire feed especially up under a rig..

the Ford garbage can muffler is too restrictive

where did u use exhaust hangers?

like the traction tires, what brand?

how the air bags holding up for u?

 

Nice work. I'd be curious to know if you get any mileage increase.
It's blasphemous I know but I've been thinking of letting go of VanGo for something more fuel efficient like a station wagon. Even my Seville with 300 HP gets around 30 on the open road.

 

I haven't had a chance to check the mileage yet, I was getting about 17 mpg before.

The hangers went through the original rubber grommets. The front ones are welded to the muffler body and the back one is on the tailpipe.

The tires are Cooper All position 27x8.5 R14. I like them, they are nice and firm and help handle towing better than passenger tires.

I have had the air rides for almost a year, and they are doing well. I have them inflated to 25 psi, they are rated to 35 psi.


One thing about performance exhausts. The OEM designs are a tradeoff between fuel economy, cost, performance, and manufacturing speed. OEM designs put precedence on cost and manufacturing, but we are not bound by the same restrictions. The issue is not about if the OEM system could be improved, but rather what does it cost and will that cost return. For me its a no brainer. I used my own brand muffler, my own brand exhaust tip and my own brand flex joint, and choose one of the shops I do business with and trust to do an install. Took a little under one and a half hours. The total including parts was 197. Replacing a flex joint, muffler and tailpipe with OEM style stuff would in all probability cost the same.

OEM mufflers are incredibly restrictive. In addition to this one being a 2" muffler, which is marginally sized, inside the muffler body, it reduces to 1.75". This is how they reduce the sound on most OEM mufflers. It then goes through several baffles in type of labyrinth. There is no attention to how it flows through this, only that it reduces noise and is cheap.

The muffler helped more than anything else on this design. Any performance muffler would give noticeable gains to performance. The key is sticking close to the OEM size on the pipe. The manufacturer knows a thing or two about what size pipe to use and where to use it. The OEM pipe through the cat is 2.25". This should have been used on the entire exhaust system, but Ford wanted the cheaper flex, muffler, and flanges. If you want to do anything similar on your own rigs, keep the changes in moderation. Don't go wild and run 2.5" or 3" pipe that is too large and will result in a peaky narrow powerband. Modest improvements to OEM are the ticket. This van is otherwise stock. I use the OEM paper filter, an unmodified airbox. The intake run is all factory.

The y-pipe in the exhaust is a restriction, but it is more time consuming and technical to replace. The problem is that it merges too aggressively. To scavenge properly, you need as graceful a transition as possible. On the 4.0L, doing it right is complicated by the oil filter location. To redesign the y-pipe, the filter must be relocated. All these issues add up in price very quickly, and while they are an improvement on an absolute scale, the price tag may not justify it. In addition to changing the y-pipe, it should merge into a 2.25" pipe leading into the first cat, but the OEM pipe is 2". The O2 sensor threads right into this zone. This ensures as accurate a reading as possible, but it also makes the sensor a restriction in an already questionable y-pipe. Possible solutions include custom fabbing a new y-pipe that better merges and feeds into a larger pipe, or using a replacement converter than has dual inlets with a center O2 port. Either method works, but the cost for this kind of modification is pretty high. There is not much room to work with in this part of the system. The returns would not be as great as the cat-back either.


In any case, if any of you have any questions, I will be more than happy to try to answer them as best I can. If any of you have been thinking of doing something similar, I can hook you up with some of the parts at a discount.

 

Points for an excellent post Mr Bear. Above all you hit the nail on the head when you said "The issue is not about if the OEM system could be improved, but rather what does it cost and will that cost return." Then you need to ask yourself what kind of return is important to me? For myself it's fuel economy, the Aero performs well enough otherwise. If my system were failing there would be no hesitation in replacement. As it is the darn system won't fail. To dump a good system just won't pay back.

 

I agree completely. My system was on the verge of failing anyway, and so the cost difference between replacing with OEM style pipes versus upgrading to a high performance was a no brainer. But to tear out a perfectly good system to install a performance system is hard to justify unless you just have to feed that ego.

 

Hey i have those bags in my aero... this looks like a good upgrade (the exhuast) specialy since we do heavy hauling... any one know where i could get this done in portland, oregon? also... any one who cares... don't let lesschwabe (imo) put the bags on...

 

Nice job, and that tip...real cool!

 

Ok, now to here the sound. This video isn't the highest quality. Also the vehicle isn't going very fast. The main point I am trying to make is that it sounds great, but notice that it is not very loud inside the cabin.

http://homepage.mac.com/tyranitar/.c...up.mp4-zip.zip

I am not positive that Windows Media Player will open this file. It should, but if not I use Quicktime.

 

Portland Muffler could probably do something like this. That reminds me, I need to get in touch with those guys. My brother used to make runs into that area, but since he left, we focused more on the SLC market. The muffler we use is the FullBlown brand, which is a clone of FM, but the 50 series we make is slightly different than the original 50 series. It is constructed differently inside, which IMHO sounds better than the overpriced original.

 

Ok, here is a sound sample at the tail pipe. This file is in .wav format so everyone can hear it. The sound quality may vary with you pc speakers, but you get the idea. There is some sound distortion that has to do with the quality of the microphone we used.

http://www.bearriverconverters.com/s...seriesaero.wav

 

hmmmmm ok i'll look into that... the 3.0 i recently bought runs almost perfectly... accept that it needs a new muffler/back pipe... cats seem to be ok (doesn't have any symptoms of clogged cats...) but the car sounds like i choped the pipe off... which i don't like. overal its mainly annoying... but some how i don't think its good for the motor either... so basicaly i'm thinking everything new from cat back, and i want to run stock 4.0l size piping, should be more than enough. any thoughts? also, i know headers are smaller on a 3.0, so i may pull some off a upull it van and do some fabricating in shop class this fall... :-)

 

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.