Diavolo, I simplified things a little bit. The upstream sensors measure the amount of oxygen left over in the exhaust as it leaves the motor. If the motor knows how much fuel and air was let in, so, it makes sure that there is nearly no left over oxygen. Then, as the exhaust travels through the cat, the remaining oxygen is pretty much used up doing the last bit of converting the CO to CO2 and burning the last little bit of fuel. So, the downstream sensor will measure the last little bit of oxygen. Then the computer looks for a difference. The computer will also look at when the voltage fluctuates and relate that change to a specific cylinder.

 

I'm basically just trying to free up the flow of exhaust over stock. A lot of people will say that the exhaust on our cars is actually designed quite nicely but I'm out to at least give it a valiant effort to do it a little better. Free up something there, if anything.

Just givin the high flow cats, the mandrel bends, and the more free flowing mufflers I expect to see some sort of gain. These headers, on the contours/cougars with cat back exhausts, are getting a dyno'd 30hp at the wheels with CAI and a tune. I'm thinking that without the tune being available I should be ok hoping for a measly 10hp lol. Not to mention that I'll be getting rid of a pretty good amount of ambient heat in the engine compartment so that ought to improve performance conditions as well. Better throttle response too I would imagine. But, its also probably going to sound like the meanest 2.5l x type ever

I'm going to keep 2 cats and 4 sensors so nothing changes. Fuel, oxygen and spark levels won't be changing so I'm pretty certain the light will stay off. One of my biggest goals here is to do this rather large modification and keep the CEL off.

If the system is just too dang loud I'll look into a resonator but I want to try it without one first.

 

Indeed, and those contour/cougars don't have the cats built into the exhaust manifolds like the x type does, so I'm expecting better gains on the x type, with a better CAI setup anyway. One of my next projects is to get the battery into the trunk and reroute my intake where the battery is, with a fresh air hose (I have some NASCAR brake duct hose and carbon fiber intake ducts) from the lower grill to the "intake box" I'm going to make for the cone filter to sit in just behind the drivers headlight. Sitting over the valve cover, behind the radiator, with the cat just below it isn't doing any good.

 

No resonator might hurt your ears and performance.

 

I think its fun to modify things, just to have something different than everyone else. Its a reflection of one's personality.
If it makes a cooler sound then it's all good because that makes the car more rewarding to drive.
I'm captivated by this thread if you haven't noticed haha.
WHAT?!! Are you saying a 30hp increase at the wheels? Thats hard to believe. Do you have a link? (actual non-biased data, not from someone selling the parts)
The most I saw searching online was a 8hp gain. Which sounds realistic based on my experiences with tuning.
I don't know if you'll gain 10hp? I hope you do.
Are you going to dyno it before and after?
My guess unofficially, is that your mods will be worth at least 25 butt-dyno horsepower, cause like you said, its going to be the meanest sounding.
You shouldn't have any CELs with that set up.
However, if you would like to do a resistor mod in place of a downstream O2 let me know. I'm sure I can make one, and send it to you for free.

My concern about your planned set up, is all your efforts will go unrewarded because the car's brain won't know how to take advantage of its new piping.
It might run fine and sound mean, but just be less fuel efficient.
If the new system is heavier than the factory piping, then that added weight will just be more performance loss.

Isn't there a way to have an open source tune done on your car locally?
If not, what about these guys:
car tuning remap tuning tools and services from home - do it yourself car tuning
I found them while searching for some sort of E-tune.
Any piggybacks that will work? like a Apex'i AFC?
AFC NEO - Electronics
Apexi SAFC Air Flow Converter from AlamoMotorsports

Looking forward to your updates.

 

There are many dyno graphs on contour/cougar forums of people with 3.0 swapped cars gaining 20 to 30 hp with the headers, an intake and a tune. Granted the tune is probably 15hp of it. The computer will learn to some extent to adjust for the headers, but a proper tune will get the most gains. These duratec v6s flow really well but the exhaust manifolds, on every variant, are one of the biggest restrictions in power. If you take note of the rated hp of the x type 3.0 vs the s type or Lincoln LS 3.0 the x type makes less power, and the biggest difference in the engines are the exhaust manifolds. Since the S and LS are rear wheel drive they have better flowing exhaust manifolds. Taking the cats out of the engine bay will aid with power gains too since the air in the engine bay will be a bit cooler, so the engine will be sucking in cooler air.


We keep talking about HP gains, but I'm really more interested in what kind of low end torque gains we get with the headers. But lets be honest, find a video of a contour with headers and a decent exhaust and the sound alone will be worth the work.

 

Justin, if you are after low end torque, then opening up the exhaust is going to hurt the low end torque. Backpressure is what makes low RPM torque. You open up the exhaust, the backpressure goes down and now the low RPM torque follows too. High RPM power and low end torque are normally opposites when it comes to motors unless you are going with say a whipple supercharger (but then you don't get mid RPM power as it can be had with other mods). I did a lot of playing with the exhaust on my Expedition and I was able to get great low end torque and if you looked at my torque curve, it pretty much maxed out at 2,000 RPM and then remained steady as the RPMs went up. But, when you are out 4x4ing, you don't normally need the 5,000 RPM power, you need the 1,500 RPM grunt.

If you are wanting to help that low end torque, then running 2" exhaust will be necessary, unless you are running a single pipe most of the way, then you could get away with 2.25" pipe.

 

That's why I am going with 2 inch. When I added headers to the mustang I used to have I got more HP gains than tq but I still gained tq. Most of the time you always gain both, with tq gains typically being less than HP gains. I'm not suggesting that somehow I'll gain a bunch of TQ but I'm sure I'll gains some. Realistically if I wanted to gain more tq than hp with headers I'd need to build some custom equal length long tube headers, but that would be a nightmare or cost waaaaay more than I am willing to spend at this point to have someone do. The way I'll be using my car I'll want more of a higher RPM power band anyway for autocross and track days, but if I get a little bump in the lower end and throttle response that would be nice for daily driving. Really the best way to really make more power all over the power band would be to bump up the displacement. I might end up rebuilding my 2.5 into like a 3.5 after I swap in a 3.0 since I'll have a whole 2.5 block just sitting there doing nothing. This is all just bench racing for now though haha.

 

wait, so youre saying part of that 30hp gain is a motor swap from a 2.5 to a 3.0? Then that would make sense.
For those interested theres more info on the differences available here:
Rebuilding the Ford 3.0L - Engine Builder Magazine

 

Hold up, so youre saying part of that 30hp gain X-TypeMentality wrote about is coming from a motor swap from a 2.5 to a 3.0?
Then that would make more sense, its not just bolt-ons and a tune.
So then a stock 2.5 engine makes 30hp less than a tuned 3.0 with some bolt-ons?
I only saw a difference of 5hp depending on the different model/makes/years.)
My suspicion is that the small difference in horsepower ratings have more to do with the marketing department than the exhaust manifolds.
Sometimes automakers will adjust figures based on the market and target buyer.
Just sayin'

For those interested heres more info on the engines internal differences/similarites available here:
Rebuilding the Ford 3.0L - Engine Builder Magazine

 

No I just mean that they had a 3.0 in them rather than the 2.5 that the contours and cougars come with stock. Just going from a 2.5 to a 3.0 gets you about 20hp stock for stock. Then with a tune, intake and the headers, and obviously a decent exhaust, many have seen 20 to 30hp gains over the stock 3.0 they started with. 30hp from headers, better exhaust, an intake and a tune really isn't that much of a gain since most engines can gain around 10hp or more just with a good tune. I've seen contour guys putting around 230 or more hp to the wheels with these mods from a Taurus 3.0, and the Taurus 3.0 is rated a little lower than the jag 3.0, like 210 I think. So putting down around 230 to the wheels from an engine rated at 210 to the crank is decent. Most stock, or just with an intake, 3.0 swapped contours put under 200 to the wheels. It also depends on if they went with a hybrid swap with 2.5 heads and contour intake manifold on a 3.0 block, port matched the 3.0 heads to use the stock contour intake manifold, or did a full Taurus 3.0 swap with 3.0 heads and the Taurus intake manifold, and if they used svt cams or not. Granted every engine is different, as are dynos, but the gains are still decent, especially since I paid like, 300 for the headers.


Interesting article but I'm not sure why they left out the 2.5 since the only big difference between the blocks are the liners and pistons. I guess since its a "3.0" rebuild.

 

Justin, I would not focus so much on I gained XX hp and XX torque as this is a peak number limited to a certain RPM. What I tend to focus more on is where the peak numbers are occurring at and how the overall curve looks. The big problem that I see with most modern day cars is while they can make "big numbers", this is normally occurring within say 300 RPM of redline. So, unless you are bouncing the engine off of the rev limiter, you are not going to really see the full potential of the car. Now, you start opening up the exhaust to make it more free flowing, the peak points end up at a higher RPM. In the case of a lot of modern day cars, you can reach a point where you are not hitting the peak power point unless you are raising the redline (which can be done, but comes at a cost). I guess I need to see what some of these dyno sheets look like and make a more informed decision on this.

I guess I have always like vehicles that while they didn't make big power numbers, they had a pretty good low RPM torque numbers. Not the greatest for mileage, but when you go to pass someone, the car just accelerates and you are not shifting gears.

 

Yes, 30hp from those modifications is an impressive claim.
I'd still like to see a link or something that shows a baseline dyno and then a mod list, and then another dyno with the results. I've been searching and can't find anything

 

why would 'good low RPM torque" not be good for (gas) mileage?
when you go to pass someone that is when you are putting your horsepower to work, not your torque.

 

Contour.org for one has many engine builds and dynos on them. I've been reading into these engines since I got my svt contour like 6 years ago. The x types would lose more power than a contour would though with the awd drivetrain. I'm not saying we will see 20hp or more, but its not unheard of the in duratec world. Not everyone sees that much of a gain though.


Thermo, I understand what you mean. I'm really talking about the power gained over the whole power band. I've always tried to get my tq curves as flat as I could and my power band to peak and hold for a few thousand rpms depending on where the the rpms that power is needed. When autocrossing and tracking that's typically the last 3k rpms before redline, for me anyway.


All this talk really makes me want to get my car on a dyno, as is, just to see what the power band looks like.

 

Thanks. I've seen that site before; 4 years ago when I bought a Contour SVT.
I did a fair amount of research too at that time.
Still hard to find Dyno results for a before and after comparison.

Sadly my Contour SVT had a crankshaft bearing that took a crap a few months after i bought it.
Replaced it, but the damage was already done.
We barely got to know eachother.
I guess thats a common issue?
I looked into swaps back then, but decided to just get rid of it.
Plus I had 4 other cars at the time. *Certified gear head* I had to have a little of everything.
Even made a point to drive all 5 in the same day a few times since they were all so different; FWD, RWD, AWD, turbo, NA, Auto, Manual, 4cyl, 6cyl, Rotary, etc
Now I have just two cars.
Likewise, i want to put my X-type on the dyno just to see the results.
Got to finish reviving it first since its been parked in storage for so long.

 

Are you my automotive doppelganger? I had an 06 mustang, my contour, an 84 rx7 and a geo I bought for 400 bucks for a daily beater Haha. my svt ran great, until the engine harness went bad, as they do in those cars. I even had a full Taurus 3.0, msds headers and plates to port match the 3.0 heads to the svt intake sitting in my shop at the time. I was moving out of the shop so, I sold it and the rx7. Loved that contour though. I also only have two cars now haha, my x type and a 98 xk8 convertible project car. At one time last year I came across a thread on one of the contour cougar sites that was just a list of engine builds and dynos. It was saved on my old computer that died on me. It was the best list of duratec v6 builds I have ever seen haha. I need to find that again.

 

X-TypeMentality,

Back to the topic at hand,...
Are you planning headers, 2 high flow cats, keeping O2 sensors, and then going into 1 (2.25") pipe back to the Y? or individual (2") pipes back to each muffler?

Will the headers mean you have to put the cats farther back? if so (is there even room?) will you need to extend the harnesses on the downstream O2?

 

haha I think so!
If we were ever to meet, we might just disappear into a giant ball of light.

 

Lol some purely passionate folks round here, I love it. By far the best forums to be a part of.

As for vehicles I have the 02 x, a 98 astro van as my company work van, and a 71 Ford Maverick with a 302 as my old man and I's pro touring project.

As for the exhaust I'm doing the 2" duals all the way back. Im thinking no y pipe with custom fabrication off each header. Hoping to put the cats as close to each header as possible. There's room. Yes, we'll have to lengthen and possibly re route the wiring for the downstreams.

The shop here in Kalamazoo doing the work has an awd dyno so I'll probably take advantage of it. They are known for building awd sti's and dsm's.

http://www.strictlyimportmotorsports.com

I like the idea of the piggybacking. Is that possible on our x's? It says possible on most with a small list of no-go's. I'm guessing the x lands on that list?