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Full Exhaust Build

4WDlifeform

NAXJA Forum User
Location
Beaver Falls, PA
Due to my inspection soon arriving I decided to fix the exhaust up since it will more than likely fail. So, started thinking If I am going to fix the muffler, why not toss a CAT on? then thought, oh boy! Flex tube seems smart! And the snow ball continued....

So, here we go. A full, 100% custom exhaust..... Soon to come! I made the appointment, acquired a bunch of stuff, and now just got to wait till I get her back.

I think the biggest part of this build is going to be the headers. I ordered APN. They seem to have great feedback on here, and were priced very well. The APN distributor sent them straight to JetHot for ceramic coating (inside and out). They arrived to my door after about 430 dollars spent and 2 weeks wait.

Why Ceramic Coating!? JetHot claims a 400 degree drop on surface temps, and a gain of 20hp from the coating alone! I temped the surface of my current stock headers at about 620 degrees F right off the block. I will be impressed to see a 220ish temp reading with the new headers! Temps were taken at "steady-state" idle. I chose this over the wraps due to the fact that they can hold moisture to the headers, and rot them. They too are (supposedly) much less effective.

I doodled up a plan that I discussed with the custom exhaust shop:

Exhaust001.jpg

The parts I am providing are:

APN Ceramic Coated Headers - $430
Magnaflow High-Flow Universal 2.5" CAT - $70
"Cherry Bomb" by Thrush - $15

Any thoughts, I am always open to hear. That was done in pencil so I can still change things! I will post up some info and pics this weekend.
 
Based on the thread I just read about a Header for the 4.0, I think the APN is a good choice on your part. ;)
 
My whole stainless exhaust system cost the same as your ceramic coating. I guess it will bring down your intake and engine compartment temperatures which is not a bad thing. Did you open up the APN header to 2.5"?
 
If you see the results Jethot claims, post up! 20hp sounds a bit exagerated, but I don't know that much about how big an impact a 400 degree drop could make.
 
My whole stainless exhaust system cost the same as your ceramic coating. I guess it will bring down your intake and engine compartment temperatures which is not a bad thing. Did you open up the APN header to 2.5"?

The install and custom piping I am expecting about 150 to 200 for parts/labor. The place I'm taking it to is awesome. Best work and they have a passion for it.

As for opening the header to 2.5... I thought it already was? if not, I'm sure this place will have no trouble doing it... I just don't know how the flanges and stuff will end up? Or, if they must, they can neck it back up to 2.5. We'll see I guess! I don't think it will kill me. My biggest hope for all this is the temp drops... not so much for power.
 
If you see the results Jethot claims, post up! 20hp sounds a bit exagerated, but I don't know that much about how big an impact a 400 degree drop could make.

Yes, I will be posting back with pics/video/data to share. I don't have a dyno, but I think a 20hp gain would be noticeable! Because I am doing the full exhaust a once, I will not be able to tell if its because of the temps... or airflow...
 
I had to open my apn header up I think it was 2.25". See if the shop can use v clamps for the flanges
 
You won't see 20 HP. That 20 HP is probably based on something making a bit more power and with a dyno tested/optimized exhaust to begin with. Probably a 600+ HP engine. You will be lucky to see 2. Even with a cold air intake, 62mm throttle body, header, high flow cat, 2.5" exhaust you won't see 20hp extra.

Where is the up steam O2 sensor?
 
Here are some pics I as able to take real quick:
PA100006.jpg


PA100007.jpg


PA100008.jpg


I have another cherry bomb in case they cant recover that one... I hacked it up pretty bad. Stupid, i know.

It is going in for the work on Wednesday this week. I am excited to see/hear it when its done!

As for what was mentioned about power gains, I could care less. I doubt I can lose any power, so that is the good in it. Im mostly in on this for the reduced temps under the hood, and sound. I guess I am expecting SOME noticeable improvement in power, but I will not be at all disappointed if it runs 100% the same as it did as it was.

I am also getting it inspected.... I gave it a quick look over, and everything looks like it should pass... I figure while this shop has it, they might as well inspect it too. I never had them inspect any of my vehicles before, so I don't know how "picky" they are going to be... We'll see. I will post up when I get it all finished!
 
So get this, Today I was supposed to pick up my jeep at 5. I drove an hour and a half to get it. (probably a mistake on my part to drive out before it was finished) but regardless, they got it done.

Bad thing is, when they fired it up, it idled at 3000. He said the thing went nuts! so, I got there at this point, and it looks like the header is too think, causing a vacuum leak. Most of the bolts hold down the exhaust and intake manifold in the same bolt. Being that the exhaust is thicker, the intake is not sitting tight. I think that is bad engineering.... Either way, the guys are sticking around late to finish it cause they dont want it there, and I pretty much need to be taking this thing home tonight.

Looking at everything though, looks great otherwise. I just really hope to get the call here soon that its REALLY done!
 
That sensor has to be after the cat; it's there to make sure the cat is working. The upstream(bank 1/sensor the PCM uses to determine AFR) is the one that needs to be in the downpipe.

Edit- what Mesh says- I would guess they didn't get the manifold seated on the alignment dowels (pins, nubs, whatever).
 
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The flange on the header shouldn't be too thick they probably installed something wrong. It doesn't seem right having a header that looks that good then using a $20 Cherry Bomb.
 
The header flange probably isn't too thick. Most after market headers have a thicker flange. Make sure they are using the correct stock belleville washers on the manifolds. There could be some interference between the header and manifold, possibly they didn't torque the bolts down correctly, damaged gasket, etc.
 
I got my jeep back. As it is right now, the idle is at 1200, engine normal operating temp. I think they rushed to get it in a "working" state just to get out of there... it was well after their normal quitting time. Hard to say though. They do really great work, which was why I drove the distance to go to them. But, for the idle being high, would anything else cause that, other than a vacuum leak on the intake manifold??

What I am curious to know is if having a much less restrictive exhaust would cause this? Maybe something needs programed or reset? I know people have mentioned having better performance with a smaller pipe diameter... Thoughts?

The sound is great! Like mentioned, nice headers with a cherry bomb does seem weird, but I think its a good combo. I am very pleased with the sound though. I will post an infamous tailpipe video tomorrow hopefully haha.

Performance... No difference. MAYBE a hair more when I wind it out... but, nothing noticeable.

I will read temps tomorrow after work to see how much that has gone down.. if at all.

Overall satisfaction, UNHAPPY. tooooooo much money for really nothing gained. I spent so much that I don't even want to mention it, cause you guys will bash me for it :twak:. If I would have known from the start what this project cost would have escalated to, I would never have done it. Maybe ill see a magical 200 degree drop on the headers and I MAY think about listing the costs!! hahaha ...but I think we all know that wont happen.
 
The reason your idle was/is too high probably is that your intake manifold isn't seated against the cylinder head causing a vacuum leak. The intake manifold needs to be notched where they contact the new APN header.
 
The reason your idle was/is too high probably is that your intake manifold isn't seated against the cylinder head causing a vacuum leak. The intake manifold needs to be notched where they contact the new APN header.

I have a feeling this is the case... They did grind off the coating where the bolts where contacting the header, but seems it wasn't enough. I will have to get a set of calipers, and really dial in on this thickness issue. But, I currently have no place to work on this. Think this is ok to run for a while? Any "quick" solutions? some bubble gum maybe haha:laugh3:
 
go look and make sure the intake is on the dowels, and then double check the torque on the bolts, and make sure they are tight is all i can say. that and make sure they hooked up all your vacuum lines
 
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