Mileage and Aerodynamics

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sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Mileage and Aerodynamics

Post by sierrablue »

So I'd like to keep the Jeep relatively stock looking, however I wouldn't mind cleaning up the aero a little bit. I don't want to do any major changes, but some minor things.

I've been thinking about an air dam for the front of the Jeep. I realize that might hurt capability some, however I only plan to go to the bottoms of the leaf springs (if you hang those up it's not going anywhere anyway). It kinda bugs me looking at the fronts of the springs all the time anyway (and I'm not 4-linking it 😉). Anybody have any suggestions on how to do this? I'd rather not drill holes in the bumper or frame if I don't have to. And any material recommendations? Also this would be good since I want to make it an EV eventually.

Any other easy aero tricks that won't look bad?

Also, I'm not spending the time/money on FI or an overdrive when I want to do an EV conversion on it, but any recommendations on other ways to improve mileage? I'm sticking with all seasons, have a vacuum gauge (and a foot that's working on losing some weight :roll: ), have and use my locking hubs, and keep it up on fluids and everything. I may be fixing the Qjet soon here so that should help with mileage too... I'm sure some other people are also curious about optimizing mileage, although may be less curious than I am.

NOTE:
BEFORE anybody goes off on me about how this is the wrong vehicle to worry about this kind of thing on, and to just leave it 'cause burning gas doesn't matter, I bought the wrong car, let me say this: I want the utility and capability of this Jeep. It looks good, and has a good solid body and frame. I could go to a Subi, but then if I asked about swapping it, everybody would tell me to go to a '90s Honda. And those guys would say go Prius. And they'd say go Tesla. And Tesla guys...well they're Tesla guys and you'd never get away from the stereotypes. My point here is that everybody is gonna tell me I'm wrong no matter what I drive, so I chose something that I actually like.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

SJTD
Posts: 1924
Joined: Tue May 21, 2013 12:02 pm
Location: Lompoc, Sunland or somewhere between

Re: Mileage and Aerodynamics

Post by SJTD »

Idunno what you have but my '84 came with an air dam.
Sic friatur crustulum

'84 GW with Nissan SD33T, early Chev NV4500, 300, narrowed Ford reverse 44, narrowed Ford 60, SOA/reversed shackle in fornt, lowered mount/flipped shackle in rear.
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tgreese
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Location: Medford MA USA

Re: Mileage and Aerodynamics

Post by tgreese »

Wow, a preemptive rant. No need to get defensive. 8-)

My feeling is the edges and frontal area of the Wagoneer are a bigger aerodynamic problem than the flow underneath. I presume the air dam is meant to direct air around and over rather than under. However, surface turbulence makes drag. You might read a bit on laminar flow and the transition to turbulence. Turbulence thrashes the air to make it change direction rapidly, which requires energy.

Anything to smooth the flow will make an improvement, although making a significant improvement may take a lot. I can imagine modern smooth mirror housings, recess the door handles, remove the drip channels, stuff like that. If that's something that you want to do, I'd suggest figuring out an accurate way to measure the effect of your changes. Maybe not a wind tunnel, but is there a way to make streamlines with smoke and box fans or something? I wonder... I'd think you could make a metered gasoline rig like was used on Mythbusters to test mileage. See the episode where they compared pickups with the tailgate up, down and missing.

Despite your rant, I'd mention that my KL gets 26-27 on the highway at a steady 70 mph. Equivalent or better in terms of off-road performance, though the entry fee may be too high for you. Not live axle, and no frame, but a 60:1 low range, 4-wheel traction control, and e-lockers front, rear and middle. For less money, ZJ and WJ GCs push 20 mpg, are affordable, and roll on live axles. The Quadradrive system on the WJ is perhaps the finest passive 4WD system ever built. Might be a way to make a big gain affordably and not compromise too much. Won't look like a Wagoneer though.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

SJTD wrote: Fri Mar 10, 2023 2:19 pm Idunno what you have but my '84 came with an air dam.
I don't have anything, the air dam was a later thing. Definitely '80s, Idk if you could get it with the bumper change in '79 or not.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

tgreese wrote: Fri Mar 10, 2023 3:01 pm Wow, a preemptive rant. No need to get defensive. 8-)

My feeling is the edges and frontal area of the Wagoneer are a bigger aerodynamic problem than the flow underneath. I presume the air dam is meant to direct air around and over rather than under. However, surface turbulence makes drag. You might read a bit on laminar flow and the transition to turbulence. Turbulence thrashes the air to make it change direction rapidly, which requires energy.

Anything to smooth the flow will make an improvement, although making a significant improvement may take a lot. I can imagine modern smooth mirror housings, recess the door handles, remove the drip channels, stuff like that. If that's something that you want to do, I'd suggest figuring out an accurate way to measure the effect of your changes. Maybe not a wind tunnel, but is there a way to make streamlines with smoke and box fans or something? I wonder... I'd think you could make a metered gasoline rig like was used on Mythbusters to test mileage. See the episode where they compared pickups with the tailgate up, down and missing.

Despite your rant, I'd mention that my KL gets 26-27 on the highway at a steady 70 mph. Equivalent or better in terms of off-road performance, though the entry fee may be too high for you. Not live axle, and no frame, but a 60:1 low range, 4-wheel traction control, and e-lockers front, rear and middle. For less money, ZJ and WJ GCs push 20 mpg, are affordable, and roll on live axles. The Quadradrive system on the WJ is perhaps the finest passive 4WD system ever built. Might be a way to make a big gain affordably and not compromise too much. Won't look like a Wagoneer though.
Well, every other time I've asked about stuff like this, I get "it doesn't matter drive it how you want to and forget about trying to help the mileage." And people tell me to go buy a '90s Honda. I wanted it to be clear that that was not what constructive to what I'm getting.

In reality the frontal area is on par with a new GC or Wrangler. The new ones have a lower coefficient of drag, but have the same/more frontal area. The air dam keeps some air from going underneath, which does create some drag up front, but makes it a smooth blockage, vs. going underneath and having to go around the springs and the engine/transmission, all of that. Obv it doesn't keep all of the air out of there, but it helps.

I might consider shaving the door handles or something, but I'd really rather not. I don't want to repaint anything in the process of changing things. The drip rails are good to have.

Ah yes, the Fiat (fix it again Tony) of the Jeep world. A Dart on stilts? Not saying it's bad for you to have it, just not something I'm interested in. I don't like leather or screens in there, and don't need A/C. And I don't care about the low range all that much, I rarly would use it anyway. As far as the ZJs go, we have one, and the transmission tunnel is in just the wrong spot for my body--it causes me pain to drive it like that. And the WJs and ZJs both...still have that 4.0 or a not great V8, and again, just not what I want.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

letank
Posts: 4010
Joined: Wed Oct 03, 2012 9:16 pm
Location: SF bay area

post hack: about the KL

Post by letank »

tgreese wrote: Fri Mar 10, 2023 3:01 pm
I'd mention that my KL gets 26-27 on the highway at a steady 70 mph. Equivalent or better in terms of off-road performance, though the entry fee may be too high for you. Not live axle, and no frame, but a 60:1 low range, 4-wheel traction control, and e-lockers front, rear and middle. For less money, ZJ and WJ GCs push 20 mpg, are affordable, and roll on live axles. The Quadradrive system on the WJ is perhaps the finest passive 4WD system ever built. Might be a way to make a big gain affordably and not compromise too much. Won't look like a Wagoneer though.
Interesting about the very good mileage for a V6, I really never looked at newer jeeps, but recently drove a 18 GC trailhawk with 100Kmiles, impressive, but may not make it on our poorly maintained forest roads, unless I remove the bumpers, which seems like the weak point of most SUVs, unless you buy a pick up ...

How many updates did the KL ZF 9 speed transmission needed?

Back to topic, lowering the body with selectable hydraulic suspension "à la citroên or Land Rover" would increase your mpg, as we know that a lift decrease your mpg.
Michel
74 wag (349 Kmiles... parked, next step is a rust free body)
85 Gwag (229 Kmiles... the running test lab)
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tgreese
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Location: Medford MA USA

Re: Mileage and Aerodynamics

Post by tgreese »

The ZF 9HP48 has been updated once since I've owned it. That came when it was newish to me, and after I complained about the annoying non-downshift at a rolling stop. The Jeep still wants to hang in third at anything other than a full stop, but I have adapted. I'd mention that mileage figure is what's reported by the vehicle on the dash. Unless I go on a long trip, it stays around 17-18 with a mix of city and highway. I'm a light-footed driver.

Responding to your interest, It's a 9-speed, but I've never been in 9th. Fastest I've driven is about 85, and that was not enough to select 9th. According to its TSM, the 4-cylinder KLs get a lower final drive ratio, and I expect you'd reach 9th in them.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.
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tgreese
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Location: Medford MA USA

Re: Mileage and Aerodynamics

Post by tgreese »

sierrablue wrote: Fri Mar 10, 2023 3:50 pm ... Ah yes, the Fiat (fix it again Tony) of the Jeep world. A Dart on stilts? ...
My KL is pre-FCA. Made by Chrysler LLC, post Daimler. And what's wrong with the Dart? Apparently it's the other recipient of the 3.2L V6. I drove one on a trip to the Everglades, and it seemed fine. We saw crocodiles!
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

tgreese wrote: Sat Mar 11, 2023 1:32 pm
sierrablue wrote: Fri Mar 10, 2023 3:50 pm ... Ah yes, the Fiat (fix it again Tony) of the Jeep world. A Dart on stilts? ...
My KL is pre-FCA. Made by Chrysler LLC, post Daimler. And what's wrong with the Dart? Apparently it's the other recipient of the 3.2L V6. I drove one on a trip to the Everglades, and it seemed fine. We saw crocodiles!
Oh. Maybe it's before all of the reliability issues I've heard about...

I like the Dart, but the main things I like about them are that they're nice and small, and handle relatively well...which the Cherokee kinda doesn't do any of those things. I'm sure the handling and stuff is decent, but it's just not the same...
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

Disclaimer:
Apparently my comments about the Cherokees are offensive to some. If you like them and want to drive them, that's fine, I just gave my personal thoughts on them, for what I'm personally doing. Sorry to anybody I've offended, that wasn't my goal. I respect that they're relatively capable and get you from a to b. They're just not for me.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

candymancan
Posts: 3652
Joined: Tue Mar 22, 2016 11:32 pm

Re: Mileage and Aerodynamics

Post by candymancan »

My wagoneer went from sagged slrings 3 in hs lower to the ground using street tires.. getting 13.5mpg on the interstate.. To 13.5mpg with new springs plus 2 inchs of lift.. So i gained 4 inchs nearly after it settled.. over sagged springs.. i also gained 2 inchs of ride height using 31s over the 28 inch tires it had. I added brush guard.. 7 offroad round lights.. 5 on a roof rack that sits on my roof rack...

In all i added 1000 lbs over stock weight.. lights on top adds drag.. increase in height added drag.

And i lost 0mpg litterally 0. Its weird actually.

I got 11.5mpg last weekend going 180 miles at 70mph driving up to the mountains going up hill. So honestly it seems these engines dont really lose gas mileage for added weight and drag.

As for other Jeeps..my 5.9 limited ZJ gets about 18 mpg on the interstate at 55-60mph if its a strsight not going up mountains. Like the interstate 95 in northern va to say d.c or md. But if i get on interstates with 70-80mph speed limits i get about 15mpg. City the thing barely pushes 11mpg with stop lights everywhere.

My moms 4.0 ZJ with now 400k miles. Gets 21mpg highway even at 75mph.. its crszy actually how good the fuel mileage on this old Jeep. In the city i easily get 16mpg.

Honestly. I dislike any newer Jeep from 2005 on up.. Ive been thinking of getting myself an XJ cherokee/commanche. Or another ZJ with the 4.0 to use as my (hooptie) for better gas mileage.

Everyone tells me to get a cheap car so i csn get better mileage. But na i love Jeeps too much... so a nice 500-1000$ ZJ with a 4.0 i can repair as i know them in and out. Would be a nice money saver. My waggy uses way way way too much gas for any long trips.. It needs 93 as well or it pings. My 5.9 limited zj.. same thing. 15mpg interstate sucks. And it needs 93 as well.

So im getting terrible mileage on both Jeeps AND i have to pay like 70 cents more per gallin thsn everyone.

So ya 21mpg on a ZJ using 87 octane would be so much nicer. And i still get to drive a Jeep i prefer and rely on.

You wont catch me in a wrangler. Or 4 door wrangler. Or any pentastar v6 or 5.7 hemi lifter ticking peice of crap fiat stellantis Jeep. Ive seen far too many 2005-2017 Jeeps with lifter ticking at 100k miles. Theyre junk vehicles. If i offend anyone. I dont care. Grow some skin its just my opinion. New Jeeps the milege didnt change much either.. so you get 26 mpg vs 21mpg. The percentage from that to say 15 and 21 is lower. So it isnt a big Jump to justify the cost of buying one

The other reason i dont wranglers.. Is it just a total meme now for women to drive them. And men who pay to have mods put on. Dont wanna break a nail doing it yourself now do we. Also everyone has one. I like to be a little unique. No one has a wagoneer. No one has a ZJ or XJ anymore they have practically disapeared on the road. Or a 5.9 limited like i do. Its just something to set you apart.

Hell the 5.9 limited is now becoming ( collectors) aparently the hipsters are making videos of them on youtube as the Jeep to buy and collect.. lol

Call me a snob but ya.
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

candymancan wrote: Tue Mar 14, 2023 6:13 pm My wagoneer went from sagged slrings 3 in hs lower to the ground using street tires.. getting 13.5mpg on the interstate.. To 13.5mpg with new springs plus 2 inchs of lift.. So i gained 4 inchs nearly after it settled.. over sagged springs.. i also gained 2 inchs of ride height using 31s over the 28 inch tires it had. I added brush guard.. 7 offroad round lights.. 5 on a roof rack that sits on my roof rack...

In all i added 1000 lbs over stock weight.. lights on top adds drag.. increase in height added drag.

And i lost 0mpg litterally 0. Its weird actually.

I got 11.5mpg last weekend going 180 miles at 70mph driving up to the mountains going up hill. So honestly it seems these engines dont really lose gas mileage for added weight and drag.

As for other Jeeps..my 5.9 limited ZJ gets about 18 mpg on the interstate at 55-60mph if its a strsight not going up mountains. Like the interstate 95 in northern va to say d.c or md. But if i get on interstates with 70-80mph speed limits i get about 15mpg. City the thing barely pushes 11mpg with stop lights everywhere.

My moms 4.0 ZJ with now 400k miles. Gets 21mpg highway even at 75mph.. its crszy actually how good the fuel mileage on this old Jeep. In the city i easily get 16mpg.

Honestly. I dislike any newer Jeep from 2005 on up.. Ive been thinking of getting myself an XJ cherokee/commanche. Or another ZJ with the 4.0 to use as my (hooptie) for better gas mileage.

Everyone tells me to get a cheap car so i csn get better mileage. But na i love Jeeps too much... so a nice 500-1000$ ZJ with a 4.0 i can repair as i know them in and out. Would be a nice money saver. My waggy uses way way way too much gas for any long trips.. It needs 93 as well or it pings. My 5.9 limited zj.. same thing. 15mpg interstate sucks. And it needs 93 as well.

So im getting terrible mileage on both Jeeps AND i have to pay like 70 cents more per gallin thsn everyone.

So ya 21mpg on a ZJ using 87 octane would be so much nicer. And i still get to drive a Jeep i prefer and rely on.

You wont catch me in a wrangler. Or 4 door wrangler. Or any pentastar v6 or 5.7 hemi lifter ticking peice of crap fiat stellantis Jeep. Ive seen far too many 2005-2017 Jeeps with lifter ticking at 100k miles. Theyre junk vehicles. If i offend anyone. I dont care. Grow some skin its just my opinion. New Jeeps the milege didnt change much either.. so you get 26 mpg vs 21mpg. The percentage from that to say 15 and 21 is lower. So it isnt a big Jump to justify the cost of buying one

The other reason i dont wranglers.. Is it just a total meme now for women to drive them. And men who pay to have mods put on. Dont wanna break a nail doing it yourself now do we. Also everyone has one. I like to be a little unique. No one has a wagoneer. No one has a ZJ or XJ anymore they have practically disapeared on the road. Or a 5.9 limited like i do. Its just something to set you apart.

Hell the 5.9 limited is now becoming ( collectors) aparently the hipsters are making videos of them on youtube as the Jeep to buy and collect.. lol

Call me a snob but ya.
Sounds like you need a 2.5/5-speed XJ with 4.56s lol. It wouldn't be fast but it'd get 23 mpg+. Our 2.5 2-door XJ gets about 22-23 in the summer, and it has a non-overdrive automatic.

I do have to disagree on the JL Wranglers. Those are actually really nice and fix a lot of the problems that the JKs had. Don't get me wrong I hate all the electronics, but the basic platform is really good.

What's wrong with women being into Wranglers? They give you priceless looks when they're like "yeah I have a Jeep too" and you walk out and get in your lifted station wagon (well, in the looks department) with "Jeep" badges on it 😂 (and then go all the same places their brand new Wrangler struggles to go).

I do have SOME respect for the people that don't do their own work. A lot of them don't have either the time, the tools, or the knowledge of how to work on them, or some combination. Or they physically can't do the work themselves. I have a little less respect for those that do that and then burn all the extra gas from having massive tires and a lift, and then don't use it for anything more than what a gas Wrangler could do. I still respect them but am privately thinking how stupid that is. You just can't know and thus can't judge them based on that.

I like how you say that nobody has an SJ, XJ, or ZJ anymore, and we have one of each in the garage 😂 And the SJ and ZJ are even daily drivers🤣
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.

candymancan
Posts: 3652
Joined: Tue Mar 22, 2016 11:32 pm

Re: Mileage and Aerodynamics

Post by candymancan »

Well what i mean is 5 yesrs ago they were ALL over the road.. now ? They barely are in the junkyards.. As 4-5 years ago the salvage yards were PACKED with xj and ZJs.. now that theyre gone.. only the few diehards drive em.

Im noticing a influx of wj and wks now in the yards. The cycle repeats.

How does the 2.5 drive ? I saw a 2.5 comanche f9r sale.. but i dunno.. tje 2.5 in a pickup that id use to haul many 50lbs hay bails and stuff.. Does it have any power ?
1998 Jeep Grand Cherokee 5.9L Limited 219k
1998 Jeep Grand Cherokee 4.0 I6 laredo 430k
1990 Jeep Grand Wagoneer 155k
1976 Jeep J10.. 85k(repaired)

Topic author
sierrablue
Posts: 1208
Joined: Wed Nov 30, 2022 8:02 pm
Location: MN/CO

Re: Mileage and Aerodynamics

Post by sierrablue »

candymancan wrote: Thu Mar 16, 2023 6:51 pm Well what i mean is 5 yesrs ago they were ALL over the road.. now ? They barely are in the junkyards.. As 4-5 years ago the salvage yards were PACKED with xj and ZJs.. now that theyre gone.. only the few diehards drive em.

Im noticing a influx of wj and wks now in the yards. The cycle repeats.

How does the 2.5 drive ? I saw a 2.5 comanche f9r sale.. but i dunno.. tje 2.5 in a pickup that id use to haul many 50lbs hay bails and stuff.. Does it have any power ?
Stock? No. It'll move but that's about it. Ours has the Chrysler fuel injection, a 4.0L throttle body, and a home-modified YJ 2.5 header (which, now you can buy shorty 2.5 headers on eBay pretty cheap, which would be my recommendation). High flowing exhaust and stuff--if you're not on pavement it'll spin the 30x9.5 BFGs. Empty, with the lighter weight of the XJ, it'll pretty much keep up with our 4.0 ZJ. Only thing is if you run the A/C it quite literally cuts and gives you power to the point that you can feel it surge forward/slow down. More of an HP thing than torque tho.

Also with the 5-speed it'll be a whole (much better/more adaptable) animal. Assuming you're ok with three pedals anyway.

Short answer: It has lots of torque and not much hp. It won't be fast but it'll get you there. Also it's very very similar to the 4.0 in design, and has 2 fewer cylinders to cause problems.
'71 Wagoneer (DD)
-B350 (HEI, iron 4-barrel, Edelbrock 1406), TH400, D20
-'74 D44 front (nonpower discs)
-custom headliner
-Front shoulder belts (rears eventually)

viewtopic.php?t=23070

There are 2 major differences between new Wranglers and FSJs. FSJs are meant to be both utilitarian and capable, not just capable. FSJs are also rarely initially recognized as Jeeps by the average American.
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