"Gonna do it right...maybe!!??" Fuller's new XJ build!!!

My question is, if you have hrew left over, what from? Please tell us it isn’t from the links you made??!!! And, if not, to second Scooters comments 1.75 is WAY too small for that motor to breath especially under acceleration during, say, wheeling up an obstacle.
 
jeepinmatt said:
You've actually managed to make one of the best looking and most functional trusses I've seen on the offroad internet in a long time. Congrats!
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Whaaat... uhh cool (didn't see that coming)
 
skyhighZJ said:
My question is, if you have hrew left over, what from? Please tell us it isn’t from the links you made??!!! And, if not, to second Scooters comments 1.75 is WAY too small for that motor to breath especially under acceleration during, say, wheeling up an obstacle.
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No it's extra from work. Ok maybe 1.75 little small, so brought home 2" HREW to replace most of it. With many many exhaust tests and trials I've done over the years, the 4.0 torqueband is way better with more back pressure than free flowing. So 2" should be good and quiet, tough and low heat.
 
Can someone PLEASE help with finding the D70 conversion joint. I've searched and looked and I'm confused and lost, spent 30 in O'Reilly with the guy too and got nowhere. Thank you
 
What's going to be the weak link in the exhaust if it gets smashed or jammed in to something? The exhaust manifold bolts?

As for the u joint, you just need a set of dial calipers. Measuring and looking up u joint sizes is real easy.
 
marty79 said:
Can someone PLEASE help with finding the D70 conversion joint. I've searched and looked and I'm confused and lost, spent 30 in O'Reilly with the guy too and got nowhere. Thank you
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Again.
Ujoints.jpeg
 
“Measure the cap diameter... if it is 1.188" then measure the width(flat of cap to flat of cap)

If your joints has 1.188" diameter caps and is...

3.625" wide then its a 1350 joint
4.188" wide then its a 1410 joint


If by some chance your caps are 1.062" dia... then you have a 1330/1310 or 7290 etc. etc. etc. which I highly doubt because those are 1/2 ton u-joints. “

Stole his off the web and after going back a couple pages you never figured out what joints you had in the first place. Stop going to a shit-ass vatozone or advanced idiots! Call East Coast Gear Supply and be done with it by buying the appropriate spicer joint. Better yet follow the advice and have your driveshaft modified to accept the correct U-joint. You have came this far and made leaps of progress in your build don’t skimp now!!
 
marty79 said:
No it's extra from work. Ok maybe 1.75 little small, so brought home 2" HREW to replace most of it. With many many exhaust tests and trials I've done over the years, the 4.0 torqueband is way better with more back pressure than free flowing. So 2" should be good and quiet, tough and low heat.
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Then why are you asking if you've done so many tests and trials? Seriously.
Go with 2.25" like every single 4.0 came with from the factory. It'll promote better performance and help keep the engine cool under all conditions.
 
Jody Treadway said:
Then why are you asking if you've done so many tests and trials? Seriously.
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Well duh lol, I've never done it with HREW only heard good things about people doing it.

Pretty sure they don't make a ujoints that fits what I need so I guess new yoke or buy a 1350 driveshaft.
I would have to have a 1310 to 1410 3.2x4.25..not available in that exact measurements..
 
skyhighZJ said:
by some chance your caps are 1.062" dia... then you have a 1330/1310 or 7290 etc. etc. etc. which I highly doubt because those are 1/2 ton u-joints
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Jeeps are 1.06 caps, that's what makes it hard.
I'm gonna look for 1350driveshaft and build a 1350-1410 I reckon
 
marty79 said:
I've never done it with HREW only heard good things about people doing it.
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I have literally never heard a single person say one good thing about using HREW for exhaust pipe. So I cant comment on that portion. You'd have to ask those people.

The negatives that jump out to me are:
- Size as mentioned.
- Inflexibility, HREW will kink in a bend that thin wall tubing could make (thing axle humps) , assuming you could bend it at all.
- Weight. It will weigh significantly more, adding weight to an already heavy rig. This will be exaggerated since you dont want to solidly mount exhaust pipe (it needs some vibration expansion/contraction room) if you hang it from any standard exhaust hanger it will be challenged to not rip it off the frame. If you do find a hanger that will support it then you have additional swinging mass which is adding stress onto the exhuast manifold where it bolts up. 4.0 Exhaust manifolds aren't exactly known for their strength and resistance to cracking...
- More logistical, you will need a belled end and sleeve to connect to the manifold output. Since the HREW is a different OD a factory coupler wont slide on it. The ID wont match up to you exhaust manifold. If you use a short piece of existing tube from the manifold they wont mate up together properly.
-Finally exhaust tubing is cheap. My local guy charged my son $45 to run dual 2.5" straight pipes on his k5 from headers out. Parts and labor.
You can buy 13' sticks at Advance auto for $20. Why reinvent the wheel to possibly save $20. You will have way more in the adapters to make it work

I can't wait to see how you make it work though, Im sure it will be creative. Build looks good so far, keep it up!
 
marty79 said:
No it's extra from work. Ok maybe 1.75 little small, so brought home 2" HREW to replace most of it. With many many exhaust tests and trials I've done over the years, the 4.0 torqueband is way better with more back pressure than free flowing. So 2" should be good and quiet, tough and low heat.
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But...what is the wall thickness? That is what will determine the ID, obviously. 2" exhaust (or the stock 2.25") typically has a wall thickness of 16 gauge...bringing the ID to 1.875 for 2" OD, or 2.125" for 2.25" OD. You'd really be limiting the torque band on that motor by doing something that heavy.
Croatan_Kid said:
What's going to be the weak link in the exhaust if it gets smashed or jammed in to something? The exhaust manifold bolts?

As for the u joint, you just need a set of dial calipers. Measuring and looking up u joint sizes is real easy.
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Great point with the weak link. Bash that thing on something solid, and it'd be the manifold bolts either at the block or at the collector becoming your weak link...or cracking the manifold altogether.
Jody Treadway said:
Then why are you asking if you've done so many tests and trials? Seriously.
Go with 2.25" like every single 4.0 came with from the factory. It'll promote better performance and help keep the engine cool under all conditions.
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What he said. Engineers that designed the exhaust system just might know a thing or three about what gets the best overall power curve.

Again, going with something with a lesser ID will probably net you with an incredibly short power band. I'm thinking that you'll probably be ending up with your secondary pipes (the main exhaust pipe coming out the back, I mean) being something similar in inner diameter to what the primary tubes are in the exhaust manifold. Shoving 6 things of a particular diameter into one hole of the same size might not be too...comfortable? ...so many bad things could be said about that statement.... :D
 
Croatan_Kid said:
What's going to be the weak link in the exhaust if it gets smashed or jammed in to something? The exhaust manifold bolts?
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Ron said:
Why reinvent the wheel to possibly save $20. You will have way more in the adapters to make it work
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No reinventing, just why not. Performance gains, durability, free materials and got it done in an hr. Well see if I like it once I drive it. I love experiments with exhaust
 
To comment on making exhaust bends without a tubing bender - it's not too hard, but it is tedious. Some people will make miter cuts and weld them together. It not only ends up not looking good, but the sudden change in direction really impedes the exhaust flow, once again being a restriction. You could do a series of pie cuts (mmm...pie...) to make the bend, then weld them all together. I've seen me do it to make a gentle bend in a piece of tube where I didn't have a bender. Again - tedious, but not too hard.
 
marty79 said:
No reinventing, just why not. Performance gains, durability, free materials and got it done in an hr. Well see if I like it once I drive it. I love experiments with exhaust
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Not gains...performance losses are at hand here. You'd really be limiting yourself. If you needed to do a full throttle stab at something, your torque is going to be way low in the RPM range...which only mathematically adds up to even lesser horsepower.
 
If he'd have just put some 2.5" exhaust pipe on it and maybe freed up the intake side of things, he might have been on to something.

You think the manifold bolts would break off in the heads or would the manifold itself crack first? Inquiring minds want to know!
 
Croatan_Kid said:
If he'd have just put some 2.5" exhaust pipe on it and maybe freed up the intake side of things, he might have been on to something.

You think the manifold bolts would break off in the heads or would the manifold itself crack first? Inquiring minds want to know!
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My thoughts exactly. And I'd put my dollar on the manifold cracking right down in the valley of one of the 'y' right before the collector. (Not that they do it on their own in the 4.0 engines after a bunch of miles anyway...)

But on the other hand, landing on a solid pipe would put a ton (literally) of torque on those itty bitty bolts...hmmm...
 
Scooter402 said:
Engineers that designed the exhaust system just might know a thing or three about what gets the best overall power curve.
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Aw cmon u don't believe this do you. They "engineer" for economy and EPA regulations junk not performance in mind.
Scooter402 said:
You could do a series of pie cuts (mmm...pie...) to make the bend, then weld them all together. I'
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Y'all gorget I work in a shop with such tools as bender now lol
Scooter402 said:
your torque is going to be way low in the RPM range...which only mathematically adds up to even lesser horsepower.
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That's what I want is torque not hp. I'm trying to build a crawler not LS buggy. More torque is what I'm after for the low end crawl and bumping it. High revs, nah.
Turbo guys been doing DOM exhaust for years now gaining from it due to the resonance and smooth wall bends (like mandrel bent exhaust) so nothing new here just not as common
 
Scooter402 said:
But on the other hand, landing on a solid pipe would put a ton (literally) of torque on those itty bitty bolts...hmmm..
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There will be skids when all done and said. I'm not redoing my exhaust after every trip lol, heck with that!!
 
marty79 said:
Aw cmon u don't believe this do you. They "engineer" for economy and EPA regulations junk not performance in mind.

Y'all gorget I work in a shop with such tools as bender now lol

That's what I want is torque not hp. I'm trying to build a crawler not LS buggy. More torque is what I'm after for the low end crawl and bumping it. High revs, nah.
Turbo guys been doing DOM exhaust for years now gaining from it due to the resonance and smooth wall bends (like mandrel bent exhaust) so nothing new here just not as common
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Turbo guys don't go off-road.
DOM isn't HREW.
A powerful engine is an efficient engine is a clean engine.
 
marty79 said:
Aw cmon u don't believe this do you. They "engineer" for economy and EPA regulations junk not performance in mind.
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Well...true, to a point. They engineer for economy, emissions, etc. etc. but that's due to the ignition timing and combustion characteristics. Exhaust flow is still something that I would think is kept in mind.
marty79 said:
Y'all gorget I work in a shop with such tools as bender now lol
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I did forget that. The fab shop I worked in only had a pipe kinker, not a tube bender...so that's good!
marty79 said:
That's what I want is torque not hp. I'm trying to build a crawler not LS buggy. More torque is what I'm after for the low end crawl and bumping it. High revs, nah.
Turbo guys been doing DOM exhaust for years now gaining from it due to the resonance and smooth wall bends (like mandrel bent exhaust) so nothing new here just not as common
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My whole point here is that you'd be limiting the torque you have, i.e. moving the total torque curve lower in the RPM band, and giving yourself overall less power. The torque curve will be lower, and HP=(TqxRPM)/5252...QED.

There is a reason turbo guys use DOM - It's to have a higher burst pressure of the tubing since they typically run stupid high amounts of boost..also for the structural integrity of the manifold/header, since it usually is supporting the full weight of the turbo and the downpipe. Not to mention the added heat... The resonance/harmonics of the exhaust has much more to do with primary tube length, RPM range, collector diameter/length, etc.
 
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