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Unread 07-16-2013, 05:47 PM   #1
CanaanTSA5
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Question for Highway Drivers with a 5.2

After 75mph on the highway, it takes a lot to get any acceleration out of my 4.0. I pretty much have to gun it. God forbid I'm going up a hill..

I'm going to be doing A LOT more highway driving soon, and although I love my 4.0 for everything else, highways are not it's thing. I've never driven a 5.2 on the Highway, how are they?

I'd love an opinion from someone who has driven both a 4.0 and a 5.2 in the same conditions, but anything is appreciated.

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Unread 07-16-2013, 06:46 PM   #2
zj97ltd
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At 75 mph my 5.2 turns around 2300 rpm. Even without downshifting if I give it more pressure on the gas pedal it steadily accelerates. Put the hammer down and forget it, you'll be over 100 in no time. I had a '93 ZJ 4.0 and at the time I didn't think it was all that bad, but this is my second 5.2 ZJ since then. The V8 has steady power where the 4.0 starts running out of steam.
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Unread 07-16-2013, 06:53 PM   #3
Mickey_D
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I agree with above. The 4.0 is a fantastic offroad engine. Balls amount of torque at incredibly low RPM's. But it's a fairly long stroke engine, which means it can't develop the higher RPM's to create good highway BHP. Whereas the 5.2 is the original Chrysler 318 that the cops used to use in the 1960's Dodge Diplomats. It's also the engine used in quite a few of the 1960's NASCAR style race cars.

It has plenty of low end torque, but its primary design was to be a high RPM range engine. As such, you get almost as much "butt dyno" from 60-75mph as you do from 0-40mph. Not quite as much (primarily because a ZJ is shaped like a brick), but close enough. The XJ with a 4.0 does pretty well on the freeway (at least my 1990 with 215/75/15's did pretty damned good), but the added weight of a ZJ (and generally larger stock size tires) make it a bit much for the 4.0.

To give you an idea, there's a stretch of I-15 south of me (down around Santaquin - Nephi) that has a 75mph speed limit. Even the state troopers will honk the horn at you to move it along if you're doing under 80mph. I came up the onramp and there was a row of about 10 tractor trailers bearing down in my rear view. I tromped it and shot from 55mph to almost 100mph a hell of a lot quicker than my wife's 2001 Neon would have. And hers has the 150bhp engine in it. Granted it's still a Neon, but 150bhp in something that's little more than a gas powered golf cart is gonna scoot! And in all aspects my ZJ will walk away from it except cornering.
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Unread 07-16-2013, 06:57 PM   #4
dnuccio
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5.2 is awesome on the highway. tons of passing power. i was on a deserted back road once and got on it hard, i had the speedo pegged before the pedal hit the floor.
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Unread 07-16-2013, 09:18 PM   #5
CanaanTSA5
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Thanks for all the replies. Answered my question perfectly. Sounds like it's worth looking into getting a Limited with a 5.2 then. I really don't want a 249, they made Limited's with a 242 correct? And do all Limited's have that higher-end VIC?
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Unread 07-16-2013, 09:30 PM   #6
kg6mov
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No 5.2 ever had anything but the 249.

Which is a better case anyway.

Get a 96+ with the d44a. They all had the VIC.
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Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-16-2013, 09:46 PM   #7
CanaanTSA5
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Quote:
Originally Posted by kg6mov View Post
No 5.2 ever had anything but the 249.

Which is a better case anyway.

Get a 96+ with the d44a. They all had the VIC.
I have a friend with a 97 Limited with a 5.2 and a 242...And he's an idiot when it comes to anything automotive, so he didn't do a swap...I guess a PO did it...?

How are 249's in the mud. I don't do a lot of mudding, I travel down a lot of roads that are entirely mud certain times of year. One of the reasons I love my 242.
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Unread 07-16-2013, 09:54 PM   #8
dnuccio
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Quote:
Originally Posted by CanaanTSA5 View Post
I have a friend with a 97 Limited with a 5.2 and a 242...And he's an idiot when it comes to anything automotive, so he didn't do a swap...I guess a PO did it...?

How are 249's in the mud. I don't do a lot of mudding, I travel down a lot of roads that are entirely mud certain times of year. One of the reasons I love my 242.
must have been swapped, because NO 5.2 ever came with a 242. some claim that there was some 5.2s in 93-94 with the 242, but noone has actually seen one.

if you dont like the 249, you can always swap it.
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Unread 07-16-2013, 09:56 PM   #9
Mosher
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i had a 96 with the 4.0 now i have a 98 limited 5.2 awd and i love it on the highway has alot more power then my 4.0 and i found the fuel was the same between the 2 jeeps but my 96 was 3 inch on 31 and the 5.2 is stock
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Unread 07-16-2013, 09:57 PM   #10
kg6mov
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It's very good in wet and slick surfaces, in general it handles much better than 2wd. The 96+ version is well balanced and keeps the power where you need it.
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1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 31's, Holes drilled in the roof.
1998 ZJ Platinum Limited 5.9, New engine and trans, no front driveshaft, but it's pretty

"Whats wrong with a PT Cruiser?"
"Coulda had a V8!"

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Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-16-2013, 10:00 PM   #11
Erbo1Kanerbo
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The 249 is superior to the 242. I loved mine even with 4.5" on 33s it was pleasant to drive and nice knowing if you were driving on a wet road or driving offroad you still have traction and you dont need to shift the transfer case. I hardly ever had to use 4LO. When it was stock it was plenty fast for an SUV
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Unread 07-16-2013, 10:18 PM   #12
CanaanTSA5
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What should I be looking for other than a bad VC when I test drive a Limited? Anything different with a 44RE than the 42RE in my Laredo that I should know?
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Unread 07-16-2013, 10:48 PM   #13
kg6mov
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Just a slightly heavier duty version of basically the same transmission.

If you warm it up and then do figure 8's it will feel like it's in 4wd part time, jumping and skipping.
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1996 ZJ Green Laredo V8, 2.5" OME and Bilsteins, 31's, Holes drilled in the roof.
1998 ZJ Platinum Limited 5.9, New engine and trans, no front driveshaft, but it's pretty

"Whats wrong with a PT Cruiser?"
"Coulda had a V8!"

96 build thread

Niner build thread

Quote:
Originally Posted by Texas ZJ1 View Post
I heard someone yell "mall crawler" from the back porch. I'll go see who said that. Be right back.
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Unread 07-16-2013, 10:53 PM   #14
Erbo1Kanerbo
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If your trying to knock the price down do the figure 8s, check behind the valve covers i bet they are leaking and if they leak enough it can cake up your crank position sensor causing it to fail, intake plenum gasket leak (oil inside throttle body). Other than that the 5.2 is a solid engine its been around a long time and is just as established as the 4.0 imo
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Unread 07-16-2013, 11:10 PM   #15
dnuccio
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VC is a good way to talk 400 off the price. ask the seller if you can take the air hat off the throttle body, open the throttle (engine not running obviously) and look down inside with a flash light. if you can see oil, the plenum pan needs to be replaced. hughes engines makes a good kit for it that includes everything you need. its around $120.

check the transmission fluid too. if it looks and/or smells burnt, run away, because a rebuild is in the near future and could be the reason the seller is selling it.
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