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Installed Aftermarket Exhaust Observations

Root Moose

NAXJA Forum User
Location
ON, Canada
It's been a week since I finally buttoned up my 2001 Jeep with a Banks Torque Tube header, APN stainless mini cats, custom stainless cat, new NTK O2 sensors and Gibson stainless cat back. I didn't get around to making a new 2.5" S-pipe - basically ran out of time.

Also added a Chinese copy of the ARB snorkel and a bored throttle body (63 mm IIRC).

I did these mods because the exhaust was rotting off and the rest was basically a kind of "if you are changing this anyway" kind of thing. I added the snorkel more for look and an attempt at "ram air" than anything.

Commuting downtown into stop and go traffic from an hour away has given me a chance to get use to the new sounds and feel of the Jeep with the exhaust.

For the most part, not a huge difference from the seat of the pants. My Jeep runs heavy, around 4200 lbs without passengers. You can tell it has a bit more power and more so torque. It doesn't kick down as much when going up hills or gently merging with traffic.

It also seems to be getting an extra ~75 km per tank in range. When the Jeep was stock I'd get ~500-520 km per tank depending on how much city driving was done per tank. My wife drove it as her daily for a number of years and then when I lifted it I didn't really have a sense of what was normal range any more. After the lift it would get 400-410 km per tank. (speedo is corrected, within a few percent of GPS at highway speeds)

Last tank was ~480 km. On 32" tires and ~4.5" of lift and a bunch of stop and go traffic I figure that is pretty good. It'll be interesting to see how it fares on the road trip. First leg is ~11 hours at four lane highway cruising speeds. With the trailer in tow that'll probably be ~110 km/h.

To be honest, I was kind of let down with the seat of the pants impressions. I figured there should be more to it.

Then I got our tent trailer out of storage and took it for a quick shake down run for about 15 minutes of driving. Ok, this is where the difference can be felt.

Our trailer weighs around ~3000 lbs or so. And it is quite a bit wider than the Jeep so it catches the air. The Jeep always felt laboured when pulling the trailer but it does not any more. I won't say it feels peppy but it doesn't sit in the back of your mind making you wish you had more engine any more. It was truly a night and day thing. Very usable and almost effortless without feeling like you are abusing the machinery.

So in the end I don't regret the changes and money spent. I would have spent a portion of the money to replace the stock crap anyway since it was time to replace. In retrospect, 13 years out of a factory exhaust in the salt belt is pretty good.

FWIW, where I live is a few hundred feet above sea level. I don't know if you guys in higher elevations would notice as much difference.
 
What gearing are you running Moose? I've done the same mods, but 4.56 gears, and I can really feel the difference.

I am running 4.56 gearing as well. I think the extra thousand pounds I'm carrying around takes the edge off the seat of the pants feel.
 
The snorkel is a bottle neck as is the stock air box.

No doubt. Between the circuitous route the corrugated hose takes and the length of it there is no way it is doing much more than adding cold air. But, it suits how this Jeep will be used. When I get to this part of the build on the Comanche I'll do something that is a larger bore CAI. That Jeep won't be used off road beyond fire roads type of stuff.
 
The snorkel is a bottle neck as is the stock air box.

Out of curiosity - whats you solution for this? Everyone says the cone air filters are a waste, so whats next ( i ran a cone air filter for years, it seemed alright) ? I opened up the front of my air box, removed the plastic piece inside the tube coming out of the box, WIX filter, bored renix TB to 60mm, pacesetter headers.
 
Everyone says the cone air filters are a waste

Everyone except me. Here's my current (crude but effective) set-up:

FIPK1.JPG

FIPK2.JPG

FIPK3.JPG


Hidden behind the heatshield is a 7" S&B Powerstack cone filter.
 
The only performance mods on my Jeep currently are a drop-in Amsoil air filter, a 62mm bored throttle body, and a Dynomax cat-back exhaust. I've found this is the perfect setup for the driving I do, and helps it breathe a little better. I have a bit more acceleration and more torque for when I pull my trailer.

I've done a bit of experimenting though, and I've found that some mods are better suited for different styles of driving. You want to help the engine breathe a bit better, without allowing it to breathe too much that you lose power in different areas of the power band.

Cold air intakes work well for increased throttle response, and so does a bored throttle body. I wouldn't go any larger than 62mm on a stock engine though. I tried a larger throttle body and it seemed way too jerky at lower speeds, and I seemed to lose a bit of torque cruising on the highway.

The same happened with exhaust. My Dynomax turbo muffler is perfect. It flows more than stock, but still has some back pressure. This way I still have low end torque right off idle, but it can breathe a bit more in the higher RPM range. I had a 2.5" Magnaflow exhaust which was straight through. The Jeep sounded great, but I noticed I had less torque right off idle, and it moved the power band to a bit higher in the RPM range. This would probably be fine for any modern V8, but I felt my engine was happier with the the smaller diameter piping.
 
^ agree, which is why I kept the stock 2.25" size when I updated my thunderbolt cat and magnaflow muffler. It kept the sound level down and didn't seem to loose any low end torque.
 
I've been towing our heavy tent trailer over 1000 miles in the last few days, over some fairly steep passes in the Appalachians (you guys out west restrain your laughter). The Jeep has been doing really well considering. Only one grade did it not maintain speed adequately and I had to put on the four ways. I'm certain it would have all been a nightmare without the mods.

Several places the engine got higher than I've ever seen it when working correctly. Probably just shy of 12:30 on the gauge. If the markings are accurate that is around 110°C. Normally it hovers around 100°.

Wednesday we'll be driving from PEI to the ferry to Newfoundland; it'll be interesting to see how the Jeep does on the Cabot Trail and Bonne Bay on Thursday. Much steeper grades IIRC.
 
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Nice thread! Can you share where you got the Header and APN Mini-Cat set up and price?

My '01 is in need of replacing the Mini-Cats and if I'm going to do that I might as well replasce the headers as well. :)
 
Out of curiosity - whats you solution for this?
If you actually need it I don't know of much of a solution except a custom one with a larger diameter. If you don't need get rid of it.
Everyone says the cone air filters are a waste,
Don't know who everyone is.
 
I like my FIPK + Amsoil filter. Bought it used for $75. I've run the same trip with the OEM filter / intake tube & the FIPK / Amsoil about 30 minutes apart. You can feel the power increase (not huge, but you can feel it). I wouldn't spend more than $100 for a quality intake tube & filter but I'm glad I have mine. Every bit helps when you are trying to keep up with traffic in an XJ.
 
Nice thread! Can you share where you got the Header and APN Mini-Cat set up and price?

My '01 is in need of replacing the Mini-Cats and if I'm going to do that I might as well replasce the headers as well. :)

I bought the header via Summit. You can find it a few bucks cheaper elsewhere but I like the "security" of dealing with Summit. No B.S. if you have shipping issues, returns, cancels, etc.

The pre-cat I found via some vendor on ebay.

We are at our final destination now and I've experienced some overheating. Gory details here:

http://www.naxja.org/forum/showthread.php?t=1114091
 
If you want a nice power increase for the street you will need to spend more money.

My XJ has Banks header and Monster exhaust, bored throttle body by Hesco, Head ported,polished, and milled with Intake Manifold ported both by Valley Head Service: http://www.valleyhead.com/index.html
Everything else stock including air cleaner.
She rips and pulls strongly to 5K RPM instead of flattening out at 4K RPM like stock. Money well spent.

Bob
97 XJ 4X4 Country Model 82K original miles
Many factory options including leather interior. Even has sunroof
 
Slightly off topic but how do you like your 4.56 gears? I am debating between a 4.11 and 4.56 re-gear but I am not sure which one to go with.

Mine is a 2001 XJ with 31" tires and an auto tranny. No off roading or heavy towing, just light trails, snow, and other light off roading. It's a daily driver so I don't want to lose any mpg and I don't want it to cruise at some insanely high rpm on the highway.
 
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