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Advantage of the TJ mid pipe?

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#21 ·
Dake said:
It has holes from being patched over and over. I was looking at the magnflow tj pipe with the converter. I also need a converter.
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So there is nothing wrong with what you have other than it's old. Just swap it out. Don't make it into a bigger project to fix a non-existent problem.
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Discussion starter · #23 ·
Don I patched it with steel not stainless so it has rusted and requires attention every few weeks
 
#24 ·
JeeperDon said:
So there is nothing wrong with what you have other than it's old. Just swap it out. Don't make it into a bigger project to fix a non-existent problem.
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Dake said:
Don I patched it with steel not stainless so it has rusted and requires attention every few weeks
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I meant swap out the pipe, but with a normal YJ pipe (and converter, if needed too). I'm saying don't convert to TJ when the routing of the stock YJ pipe is not an issue.
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#25 ·
I bet the TJ pipe loses 5 hp from so many directional changes.
I remember reading (Four Wheeler magazine) how the YJ has 10 HP less than the XJ because of the intake tube and a more restrictive exhaust. The TJ has even less HP with the horseshoe intake and an even worse exhaust. (also in Four Wheeler magazine)

The advantage of the TJ pipe? Ground clearance.
The disadvantage? Power loss. How much? I don't know. But I'm sure there is some.

Like a wrote a few days ago, my exhaust is bent and no longer hangs down.

Jeep should have come up with something better.
I will eventually.
 
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#26 ·
Chrisnvegas said:
The advantage of the TJ pipe? Ground clearance.
The disadvantage? Power loss.
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Dake, Chris' advantage means it will help 'maybe once in a while under the perfectly wrong conditions while off-road'. The disadvantage is 'every time you turn the key'.
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#27 ·
Too bad there's not dynamometer pulls somewhere on this. The few instances I've seen dyno pulls mentioned for the 4.0 there were other components (for stroker) at issue, and the TJ pipe wasn't factored. I'm not sure it has that much of an effect, but I may be wrong. At non-race motor levels it may not be a big deal. While it may bother my mind a little (horsepower loss) the 5HP Chris mentions is 2-3% in practical terms. AMC Blue motor paint makes up for that :)

I remember a tech document (Thorley?) years ago that indicated extra bends didn't change flow much if at all, but controlling pipe shape (not oval) and equal length header tuning made a big difference in flow. "Some" resistance actually helped low end more than a smaller diameter exit pipe did, both reduced upper end HP. However this was on a V8 of some sort and pretty likely had a big cam which usually hates low rpm anyway, so this may not be relevant to our motors. Just stuff I remember from my youth days of fascination with drag racing.

But these were all mid- to upper-RPM effects. So I am of the /opinion/ that for a DD/trail rig it isn't that important.
 
#28 ·
JeeperDon said:
'every time you turn the key'[/I].
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I just realized that probably half the vehicles on the road these days do not need a to 'turn a key' to start. Sort of sad. I also can't help but notice that in video these days people still say 'footage', like when it was filmstock. [Should it be 'video stream'?] Hopefully 'turn the key' will stick around too.
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#29 ·
fishadventure said:
Too bad there's not dynamometer pulls somewhere on this. The few instances I've seen dyno pulls mentioned for the 4.0 there were other components (for stroker) at issue, and the TJ pipe wasn't factored. I'm not sure it has that much of an effect, but I may be wrong. At non-race motor levels it may not be a big deal. While it may bother my mind a little (horsepower loss) the 5HP Chris mentions is 2-3% in practical terms. AMC Blue motor paint makes up for that :)

I remember a tech document (Thorley?) years ago that indicated extra bends didn't change flow much if at all, but controlling pipe shape (not oval) and equal length header tuning made a big difference in flow. "Some" resistance actually helped low end more than a smaller diameter exit pipe did, both reduced upper end HP. However this was on a V8 of some sort and pretty likely had a big cam which usually hates low rpm anyway, so this may not be relevant to our motors. Just stuff I remember from my youth days of fascination with drag racing.

But these were all mid- to upper-RPM effects. So I am of the /opinion/ that for a DD/trail rig it isn't that important.
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Maybe is isn't that bad. But maybe it is.
That's why I brought up the YJ/XJ power difference.
The intake tube and exhaust clearly make enough difference to lose 10 horsepower. So apparently it does make a difference.
And the Fourwheeler magazine article "4.0 mythbusting, true lies"
they were able to make up about 25 horsepower with some bolt on mods to the intake/exhaust.
The TJ exhaust mod was not one of them and some of the mods lost horsepower.

The OP asked about advantages. There is one.
On the other hand, how many vehicles have you seen the exhaust running at the front bumper then wrapping around the engine and heading to the rear bumper?
Yes, a certain amount of backpressure helps in some situations, but we're not talking backpressure (scavenging). We're talking about the exhaust gasses headed in the wrong direction!
I bet we won't find that on a new Hellcat!
May be no big deal, but let's always consider the potential downsides too.
From my experience, the exhaust running the wrong way is just a restriction.
 
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#31 ·
JeeperDon said:
Since 1996, when I first bought my totally stock 1993 YJ, my exhaust pipe has been in the stock location, crossing over under the front end of the trans. I have never (Ever!) hit the pipe on a rock in 21 years of off-roading.
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I don't think you're trying hard enough.
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#32 ·
Mr.B said:
I don't think you're trying hard enough.
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Oh, I've hit plenty of stuff on rocks (have parts receipts to prove it:grin2:), even the exhaust got hit at times in other places, just never hit it at the crossover. Here is a photo demonstrating my testicular fortitude (dialed to 12 for me, needed underware after this).
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#33 ·
I've seen you in action before Don. I was just joking with you.:laugh2::cheers2:
 
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#36 ·
I wonder why they decided to switch drop sides from CJ to YJ. There had to be some rationale (engineering issue? ... cost?), but I don't see it. I can maybe see a pass drop being better in that a CJ was offered with a V8. Stuffing both the drive shaft and steering on one side of a V8 would be tougher than splitting them up. Even then, why go to dvr drop when the V8 was dropped.
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Discussion starter · #37 ·
ok Don I have ran it for 26 years this way so I patched it and will replace it someday with a YJ pipe . The no oil burn smell is the only advantage I have seen here
 
#38 ·
JeeperDon said:
I wonder why they decided to switch drop sides from CJ to YJ. There had to be some rationale (engineering issue? ... cost?), but I don't see it. I can maybe see a pass drop being better in that a CJ was offered with a V8. Stuffing both the drive shaft and steering on one side of a V8 would be tougher than splitting them up. Even then, why go to dvr drop when the V8 was dropped.
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I'm trying to think in my head of which way the rear trac bar went. But I think I recall it being well above and clear of the tailpipe on the passenger side. With 'full' flex, would this impact a tailpipe on the driver's side?

maybe you didn't mean 'why does it exhasut on the passenger side' though?
 
#39 ·
From what I read, the military stopped using CJ parts so the next gen needed to share drivetrain with the XJ to remain profitable.
I read the XJ WAY outsold the YJ/CJ so having two distinct drivetrains was a no go.

So lets ponder why the XJ needed to change side from the CJ.
The CJ was a nice straight down & out.
 
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Chrisnvegas
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