Novak Headers And Exhaust Pipe Sizing

You haven't had it wound up to 5k rpm going up a sand dune yet.....

 

Picked up the fully welded system today. I have no complaints!
I couldn't come close to this with my mig setup.

 

Sa-weet! The stainless makes this a higher level of cool. Can't wait to hear it.

 

DEI heat shield on the muffler and mid pipe where it passes the transfer case.
All I have left to do is install the system and build hangers.

 

I still need to install a couple more hangers and finish the tailpipe exit area.
Here is the first fire up with the whole system installed. I'm in a metal building with metal buildings all around so naturally it sounds louder than it really is.
When I rev the engine the radiator fan is louder than the exhaust. I am really happy with the sound in person..... It doesn't really sound like a v6.... and it doesn't really sound like a v8....
The smoke at cold start is a mixture of condensation and oil from within the new pipe.

 

Has a significant deep note that seems different from the usual 225 note. Maybe that comes from the diameter of the pipe? Dunno, sounds kinda V8-ish with a cam. I presume you have an aftermarket cam.

 

I have no idea what's in the engine. The PO said it was rebuilt at some point. It was painted ford blue, Offy intake and a Edelbrock 500cfm carb so I would tend to believe that it had been out for some work. I lost all faith in the PO when I started finding fiber glassed over holes.
I do agree that the exhaust note could pass for a small v8 with a miss.

 

I threw a hanger on the tail pipe and one at the front of the muffler. I plan to put one at the rear of the muffler as soon as I do some flex testing to see what way I want to pull the system.




Next up is the ATCD.... Anti Tailpipe Crush Device.
Spring under on 33's leads to lots of drop off smashes. On a trail like the Rubicon its not if you drop off, it how many times you drop off per trip.
This started out as a piece of oilfield pipe, 3-1/2" OD, .250 wall. It should take a hit pretty good.

 

I like the ATDC, I was thinking that pipe was hanging out, looking for trouble.

 

Very nice. And if you hurt that, you have bigger problems.

 

Here is the final product. I trimmed off the exhaust pipe so it would be just inside the ATDC.
I will have to get a running video when the wind calms down.

 

Here it is.....
I put 30 or so miles on it yesterday and I am very happy with the system.
I feel like overall throttle response is improved, perhaps this is due to the 02 sensor location, mid range power from 1800-3000 rpm seems perked up a bit.
Jeep has always been pretty sporty for what it is..... its not fast by any means but has plenty of power to merge on to the freeway at 70.
At this point I can say that I don't notice any power loss going from long tube fenderwell headers to the Novak shorties. My old Long tubes were big, like 1-5/8 pipe so they were probably hurting the scavenging effect. I will need to go pull some hills at interstate speed to make a final determination.
So far I have not noticed any exhaust smell.
The exhaust is quiet enough that I am now noticing other rattles and noises.
The radiator fan noise is going to make me crazy. Currently the bottom of my radiator shroud is open, maybe if I made a lower section I could get away with a less aggressive cooling fan. It gets so hot here in the summer that I may just have to live with it. I don't tolerate overheating.....
The fuel pump is now audible as well when the engine is running.

The video does not capture how quiet the jeep is, the engine itself has more noise coming from it than the tailpipe.
At the start the engine is at 600 rpm idle, midway through I rev it up to 2,200 ish to simulate a 55mph drive down the rd.
What sounds like an exhaust leak near the engine is actually the TBI injectors firing, the whistle sound is the throttle body, its pretty common with running TBI with an open element air cleaner.

 

You can hear the whoosh of air with a carburetor too. Factory air cleaners are designed to muffle the air noise.

 

I like it. Great job.

 

That exhaust came out great. How is the noise level at higher rpms like highway driving?

 

Highway noise is nonexistent. The wind and road noise drown it out.

 

Update......
Carl and I were out in the jeep last week when we happened upon a mass of invasive species that needed dispatched. We felt that one of the recently departed was just too big to drag back to the road so we drove the jeep out to get it. After loading a considerable amount of weight in the rear we headed back to the road. Our path involved crossing a ditch that twisted the suspension up pretty good. The combination of weight and twist caused the drive shaft to contact the muffler. Its not really a big deal, the event however reminded me that I need to remedy the situation before this years Rubicon trip. When I built the system I used V bands at each end of the muffler so it would drop out easy. My plan is to have a big quiet muffler for daily driver use, and a small "high clearance" muffler to throw on for hardcore 4x4 trips. With the V band connection removing the muffler takes less than 30 seconds when using a cordless impact.
I have enough mandrel bends left over to make up a "high clearance" exhaust insert. I just need to decide how obnoxious I want to be on the trail........
More to come...

 

It looks like it self clearanced. Should be good now!

 

Kyle, now that you have figured out that this system needs redoing, I come pick it up while you build version II

 

I finally got my "trail exhaust insert" completed.
It takes about 4 minutes to install this exhaust section thanks to v band clamps on each side!
I used a ($15) 12" glass pack and a ($14) galvanize 180 degree mandrel bend to mimick the muffler shape. The end result is lots of clearance..... and lots of exhaust noise.
Really overall the noise is disgusting.... I purposely drive through town during daylight hours as slow as possible. After dark its wide open
I cant wait to get my real muffler back on.....