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In 2010 the exhaust finally rotted out on the Hardbody.
I did a wack of research on almost every 240SX and KA24 website and decided to go 2-1/2″ pipe.
- Walker 2-1/2 to 2″ reducer #41958
- 2 DynoMax mandrel bent “U”s #42332
- 4′ of straight pipe
- Magnaflow muffler (#12256)
- Magnaflow high-flow catalytic converter (#54306)
Yeah, cat. Because some of us have to breathe that air out there. I’ve been called “hippy” before; boo frickin hoo.
The old stuff came out relatively easily with my friend Mr. Plasma Cutter:
I cut the factory down pipe as close as I could, and added the 2-1/2″ to 2″ reducer, plasma cutting a hole for the emission bung:
I fabricated a couple telescoping stands to help hold things while I worked. These are great while you’re piecing together the tubing:
Nissan doesn’t give you much room to tuck the exhaust up into the chassis. Going to large size tube also causes problems. While notching the cross-members and making room would be a good idea, I just tucked it up as close as I could. The truck isn’t bagged, with no “real” plans to do so.
Everything pretty much ended up in the stock locations, using most of the stock bracketry. I had to modify the hangar at the transmission mount since the pipe clearance was limited, and the bracket was too long.
The original welded-nut end is cut off, and a u-bolt now attaches through a hole drilled in the top of the factory bracket:
All these stupid pie-cut U-bends are a major pain in the bum bum. The cat was the most challenging to fit:
I know, this picture sucks. The stainless steel muffler reflected too much light. I’ll get a better picture up someday. Maybe….
The tail pipe was a challenge. It needed to be as tight to the body as I could, without risking rattling. The axle will still likely hit the exhaust before it bottoms on the frame or box. It hasn’t hit yet…..
Tailpipe exits roughly horizontally, angled back slightly. I tried to give myself enough room to get the leaf spring shackle out if need be – it was a bugger to remove before:
What does it sound like?
Very low tone, burbly idle, slight “fart” sound. Throaty when opened up, but not obnoxiously so. A significant drone on the highway, almost as bad as a straight through glass pack. I don’t like it – the nice exhaust sound is really countered by the horrid drone at cruise. I may get a video up someday. Maybe. Before I die.
The Malfunction Indicator Lamp (MIL) came on within 20 minutes of driving. Code was “32” – EGR Function. The Engine Control Module (ECM) is checking to see if the EGR was working, and it figured it wasn’t.
The only way the ECM knows that the EGR isn’t working is by reading the temperature in the EGR port of the intake manifold. When the EGR is working a thermistor reads the temperature and sends the correct resistance to the ECM. Apparently the ECM only checks this temperature reading when it’s expecting the EGR to be operating (it looks for the reading, not the change in reading).
So…..
Disconnect the thermistor electrical connector, and stuff a 100K resistor in the socket. When the ECM checks, it sees what it wants to see, and the MIL stays off. The connector is kind of under injector #3.
My guess is the reduced back pressure didn’t change the temperature enough, so MIL turned on.
So far, zero return of the MIL.
Easy fix.
UPDATE: ONE YEAR LATER
I couldn’t stand it any more. The drone was insane. The sound overall was pretty obnoxious, and though I tend to like things bold and obnoxious, this was too much. And apparently I’m not 16 any more.
Theoretically adding a resonator should kill the drone, but there really isn’t any place to put it since I’ve kept the cat in there. Plus, the straight-through nature of the Magnaflow just means DRONE – I’m not sure a resonator would really help.
I did some research, and ended up redoing most of the cat-back:
- Walker SoundFX Muffler (single 2-1/2″ in, dual 2″ out – #17849)
- 3 DynoMax mandrel bent “U”s #42311
- 2′ of straight pipe
The Magnaflow and tail pipe were cut out, the longer, quieter Walker muffler was put in, and the tail pipes were pieced together. Since the dual tails are 2″ instead of the single 2-1/2″, I was able to gain a bit more axle clearance.
The Walker has a restriction for the inlet in the center – it looks like it necks down from 2-1/2″ pipe to a 2″ restriction. I’m not sure why this is there. Might give me a bit more back pressure and make my EGR work better perhaps….
The tips were sliced just like the previous exhaust. I tucked the tips a bit closer to the leaf shackle – I felt the way I had it before was a bit too far back. I also tucked everything up a bit higher. We’re about 1/2″ away from bed/chassis/frame in places.
The end result? MUCH quieter. I can hear wind noise and tire noise again whilst on the highway. It’s a bit throaty at idle (probably because of the large pipe), slight drone around 2000rpm, quiet on the highway (though I ~can~ hear the exhaust), and a touch of raspyness at wide open throttle. So far I can live with it.
UPDATE
I think I blew a baffle out of the SoundFX muffler. Disappointing, because otherwise the muffler was decent. For the most part, the muffler sounded ok, it just sounded, sort of….. odd. Not quite sure what it was, but just not “quite right.” Blowing the baffle initiated a change.
I wanted to go even a stock type muffler (muffler is “correct” for 90’s Chevy pickup, 350), but they were actually the most expensive.
I ended up going Flowmaster Series 50 Delta Flow (#9425502). The Flowmaster catalog says it has moderate exterior noise, and minimal interior noise. I read that as “low drone.” Of course, you never can tell until you pay the money, try it out, and regret the decision.
It’s different again. It seems “deeper” in tone, more drone than the Walker Sound FX, but less so than the Magnaflow. Not as raspy at full throttle than the Magnaflow, but certainly louder. I’m curious to see if it quiets down as it soots up. We’ll see.
Do I love it? I don’t know yet.
Frankly, as of this writing, this is year 5 of ownership. I’m kind of getting bored of it. I got 6 years out of the Sentra….
UPDATE – I don’t love it.
The Flowmaster is gone. I think it would have worked great on a V8, but the exhaust pulses from a 4 just aren’t enough to cancel each other properly. It wasn’t as loud as the Magnaflow, but it was close.
Also, the Flowmaster has an unusual echoing resonance, or a “ringing,” kind of like the exhaust sound is getting lost in the muffler. Really unpleasant. At 3000-4000rpm, it wasn’t too bad – which would be a V8 at 1500-2000rpm “cruising” if you will. Unfortunately, I cruise between 2000 and 2500rpm, and the drone and sound was bad.
The latest muffler is on now, and there’s no going back.
It’s a Walker QuietFlow3 (#22171) for a 1990 Chevy C1500 350V8; 2-1/2″ in, dual 2″ out.
And by gum, it’s pretty quiet. I can ~just~ hear exhaust note on the highway. Any drone is virtually non-existent.
Not throaty or obnoxious or droning or nasty at all.
Actually, kind of boring.
I am ~that~ old now. *sigh*