Author Topic: YJ Exhaust Pipe  (Read 4593 times)

0 Members and 1 Guest are viewing this topic.

fryedaddy

  • Guest
YJ Exhaust Pipe
« on: February 16, 2006, 10:36:47 AM »
I'm going to install a new muffler on the YJ and need to figure out what size the exhaust pipe is. It's a 92 with a 2.5. I think it's 2 1/4 but I'm not positive

SMC4WD

  • Guest
YJ Exhaust Pipe
« Reply #1 on: February 16, 2006, 11:53:34 AM »
spend a few more bucks and get a 'cat back' system.  One that comes with a muffler, tailpipe and the whole nine yards.

Performance would be increased and hopefully longevity...

fryedaddy

  • Guest
YJ Exhaust Pipe
« Reply #2 on: February 16, 2006, 12:42:11 PM »
I would but all would be lost when I bash it upside a rock.
I'm replacing this one due to rash as it is.

SMC4WD

  • Guest
YJ Exhaust Pipe
« Reply #3 on: February 16, 2006, 02:00:22 PM »
4" lift and 33's, and your still bashing it?  

Slow down lil' buddy!!

I got a Pacesetter header and the system took the downpipe right underneath the oil pan (So stupid!!).  It also had the O2 sensor facing forward too.  So I took that to an exhaust shop and had them custom wrap the whole thing infront of the oil pan, and relocate the O2 sensor.  

The muffler is up and out of the way, and Gibsons' exhaust (minus the s/s tip), runs the exit pipe right between the gas tank shield and the spring shackle.  

If I remember correctly, isn't the muffler tucked up near the transfer case?

Offline Bounty Hunter

  • Member
  • Posts: 1658
    • http://www.sija.org
YJ Exhaust Pipe
« Reply #4 on: February 16, 2006, 02:07:36 PM »
2.25" in and 2.5" out.

Consider installing a TJ front downpipe or have a custom one made (what I did) to route the exhaust in front of the oilpan sump instead of under the bellhousing where it will get smashed flat.  Real happy with mine, even enough room to remove the starter.

fryedaddy

  • Guest
YJ Exhaust Pipe
« Reply #5 on: February 16, 2006, 02:51:13 PM »
The Catalitic converter is right at the tranfercase under the skid but the muffler is behind that with the front portion in the open. I think I'll try to slide it back a little further or possibly tuck it up a little further. Looked like there was a little room? I don't have the gearing or crawl ratio yet so higher speeds are needed sometimes. I'm not bashing this thing to s-it though.

jwrape

  • Guest
YJ Exhaust Pipe
« Reply #6 on: February 16, 2006, 03:19:13 PM »
Quote from: "SMC4WD"
spend a few more bucks and get a 'cat back' system.  One that comes with a muffler, tailpipe and the whole nine yards.

Performance would be increased and hopefully longevity...


Everyone that I have read has said that headers and bigger exhaust on a Normally aspirated 2.5L is usless, doesn't add any power.  :?:

chrisfranklin

  • Guest
YJ Exhaust Pipe
« Reply #7 on: February 17, 2006, 07:12:40 AM »
As for power and headers,  I have driven cars and trucks with them before and after install.  But, right now I am only using a Borla cat-back and stock cat (formerly used an aftermarket hi-flow cat) and no header
From what I have seen, Headers definitely seem to help up higher in the rev range.

On my YJ 4 cyl, cat-back (and presumably header) exhaust mods definitely seem to help out in power/torque between about 2500 RPM -to the redline (this is after your ECU adjust to the flow changes).  Low-end torque doesn't see much of a difference and may even suffer if back-pressure is dramatically reduced due to exhaust mods.  

If you are doing a lot of OHV trails or rockcrawling where you are rolling along at a few mph and your torque is tripled or quadrupled by your low low-range gearing, then exhaust mod on the 4 are probably not live and die necessary.   But, I find the mods most beneficial for highway driving on with my YJ 4; it now acclerates fairly easily driving uphill in 5th gear and makes adequate (vs formerly anemic) power when you wind it out on the on-ramps.  The extra power is also nice for offsetting typical off-road mods that can effect highway speed, such as larger tires; and mileage actually improves a little if you keep your foot out of it.

I'd go decent quality cat-back and/or header, especially if the originals are damaged and need replacement.

SMC4WD

  • Guest
YJ Exhaust Pipe
« Reply #8 on: February 17, 2006, 01:21:22 PM »
every little helps...  

1hp here and 1hp there starts to add up.   Sure, it adds up to like 5-10 more, but keep adding a little, it helps.   Add bigger tires, or more weight, it takes away...

It's nice to have just that little extra, so that you can 'take it away'.  
(did that sound as it was supposed too?)

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
YJ Exhaust Pipe
« Reply #9 on: February 17, 2006, 01:44:34 PM »
To build on what Chris said, I would not open up the exhaust too much.  Yes 1hp here and there adds up but unless you're willing to rev high you won't be able to use it.  Most HP numbers given on performance parts is recorded at their sweet spot and not across the board.

Also, as you increase HP, you typically loose low-end torque.  Case in point.  I noticed a big difference in high-end horsepower when I punched a 1x2" hole into my exhaust.  Low-end torque was mediocure but there was noticably more power the higher the engine was reved.

Fixed the hole and the ending felt locked at the higher RPM's but low to mid torque increased.

I've mentioned this on the list, but I don't think I've mentioned it here.  I'd like to see a two stage muffler.  This would give you low to mids at lower RPM's but once you start climbing over, say 3000 rpm, it would open the second stage which would make the muffler flow increase and boost the top end, when you actually need it.

Two-stage exhausts are actualyl used on many vehicles.  Another reason for the two-state is to reduce noise at low speeds.  Lexus, Aston Martin, Mitsubishi, etc...  are only a few of the cars that use them.

In any case it's an interesting idea to get the best of both worlds.
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

trailerrails

  • Guest
YJ Exhaust Pipe
« Reply #10 on: February 17, 2006, 06:20:31 PM »
Quote from: "SMC4WD"
4" lift and 33's, and your still bashing it?  

Slow down lil' buddy!!



I took my stock exaust off because I kept catching it on rocks also. I am running somewhere around 5-6" lift with 37's.
I ended up cutting the cat off and welding a cherry bomb in it's place. The tip of the exaust now barly peeks past the skid plate. The only proble is it is a little loud when I realy get on the gas. Sorry I dont have any used pics but I have some of what it looked like before.


SMC4WD

  • Guest
YJ Exhaust Pipe
« Reply #11 on: February 17, 2006, 06:42:02 PM »
Now that thing is a beast!!   Wow!   Those aren't 33's, so I can't see that muffler (or the new set up) catching alot of anything.

very impressive skids...  but I guess any exposed areas are going to get hit.

trailerrails

  • Guest
YJ Exhaust Pipe
« Reply #12 on: February 18, 2006, 04:36:31 PM »
You can see all the dents in my exaust in that pic. I made all skids because I was denting my oil pan and exaust up also.

Offline Jeffy

  • Administrator
  • Member
  • Posts: 14934
YJ Exhaust Pipe
« Reply #13 on: February 18, 2006, 07:00:39 PM »
I think if you're crawling up waterfalls and shelfs like that you'd be better of building a skidplate that covers the muffler a bit.  Otherwise, a glasspack might be an option.  Another option would be to get rid of the muffler completely and go with a Supertrap.  Then you could tuck the muffler next to the gas tank.
Youtube Channel: https://www.youtube.com/channel/UCZNlr60GXH5OlKIFrT7P6mg
My Jeep: http://4bangerjp.com/forums/index.php?topic=2783.0
"If the motor car were invented today, there is absolutely no way that any government in the world would let normal members of the public drive one."

Cooncan

  • Guest
YJ Exhaust Pipe
« Reply #14 on: February 18, 2006, 07:09:04 PM »
I'm guessing with the extended wheel base, trailerrails has a fuel cell or fabbed a tank to go behind the rear seat.  Can you post some pics of your skids?  How thick is the steel underneath?