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Unread 08-09-2012, 07:10 AM   #1
Transamman
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Hemi vs LS (Not talking Swap) Just Engine vs Engine - Who is #1

I'm not looking for the war of brand loyalties here, just honest opinions of why you think one or the other is a better engine.
(I am thinking of putting a V8 into a JK, but I would like to avoid taking this thread toward one engine or the other over the technicals of the swap itself, rather lets hear about the engines themselves. . .I can worry about achieving a successful swap later)

I know the Hemi has a big following, but with my limited experience it really seems like chrysler engineering/design is kinda screwing us on the hemi in some ways (and some of its other engines as well perhaps)

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Unread 08-09-2012, 07:30 AM   #2
Transamman
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From personal experience,

I have owned a gen III non-dod LS, since new, that has Needed Zero (0) maintenance for 50K.
It was eazy to lightly modify for very respectable power, I get great cruising (city or highway) mpg. The idle is pretty stable, power onset & response are as good as anything I've driven. And with no EGR and the back O2 sensors programmed out (for headers, etc) the engine seems to be staying clean and hastle free.
In the interest of full disclosure I will say that I changed the spark plugs once...but that was more of a "why not, I'm already modding and its easy to do with everything already out of the way" type of deal . . . I also run a K&N which seems to get a bit of oil comming off of it after cleanings, so I take the airbox off (30 second job) once in a while and spray some sensor cleaner onto the MAF sensor. (If I did not run an oiled air filter, I don't know if that would still be necessary or not)

I also own a non-VVT Hemi WK that had 40K on it before I bought it. It gets single digit MPGs in town (even with low traffic) and doesn't do too well on the highway at 72, but it does get semi acceptable mileage if I cruise steadily at close to 50 (I'm not sure if that is because of the aerodynamics of the WK that make it a few mpgs worse at 72 than 50 or if its like one tech I talked to "guessed"-he said he wasn't sure, but he thought that the DOD only worked below 60 and after that I was running on all 8, all the time)
My hemi also has worse idle quality, and a studder on acceleration . . . as in, sometimes it takes right off, but often it hesitates. Overall it just isn't smooth at very low speeds. It also appears to need a lot of maintenance, EXPENSIVE EGRs, that problematic little sensor (forget the name right now) at the back, that is a b***h to change, and if the throttle body gets as dirty as it does, now gunked up is the rest of the intake/engine? -> from what I read, those appear to be issues with many hemi's, not just mine.


For me, it seems like a clear choice when picking one V8 or the other . . . but overall my experience is somewhat limited (especially with the hemi) and I know there are other opinions.

So lets hear them, which one do you favor, and why?
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Unread 08-09-2012, 04:46 PM   #3
w1pf
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On the other hand, I own a 2007 5.7L, and have never owned an LS.

My 5.7L has been fantastic for the 81K miles I have on it so far. Just got back from a trip to DC/VA (decided I'd rather drive than fly), averaged 19MPG including stuck-in-traffic on the beltway.

So, as always, YMMV.
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Unread 04-19-2014, 03:20 PM   #4
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LSx motors are far superior. hemi are great motors, but LSx are just better.
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Unread 04-19-2014, 06:05 PM   #5
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Personal opinion, LSX motors are the ****. Ease of maintenance and they produce reliable power even when built. Just avoid the displacement on demand. Chevy calls it ADM or something along that line and they are failure prone. But if you do get it several companies have kits to convert it out.
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Unread 05-02-2014, 02:31 AM   #6
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I have owned an LS1 and an LS7 equipped vehicle, as well as my 2010 5.7 HEMI in my Jeep.

The LS series motors are a rather broad family. This covers from the LS1, all the way to the LS9. It covers from 346ci to 427ci.

So...which LS motor? The HEMI, likewise spans several engine sizes and configurations.

Over-all, though, I feel that the LS series is a better motor.

-Less maintenance
-Similar power for displacement
-Better fuel efficiency when comparing similar ci/hp motors between the two families.

If my Jeep had been offered with an LS1 instead of the HEMI, I would have gotten it with the LS1. Contrary to published numbers, all LS1's made 340-350bhp, and LS1 cars dyno the same as 5.7 HEMI cars. Around 290whp with an automatic in front, give or take. The LS1 is just a better motor in every quantifiable way that I can think of.

Now does my HEMI suck, and do I hate it? Nope. I think it's a great motor and does just fine and I have faith in it to last a while. I just prefer the LSX series because they are better, IMO
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Unread 05-02-2014, 08:36 AM   #7
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i agree with you. though most Jk's use the LH9 truck motor. i think its more in the 310hp. with a 4 or 6L80 auto. hemi is iron block, so its heavier. BUT a hemi will bolt to the jeeps W580. If you have the w580 and its a Rubicon, the rubicon's transfer box used for the w580 auto is not the same as the manuals Tbox. It will not bolt up to the 6L80. you have to use a Chevy tbox. so most just pull a Silverado's lh9/6l80 and tbox. use that. The LH/Ls motors can run in a stand alone so you are not going to be SOL when the jeeps CanBus goes down. There is more on this at Pirate off road.
one day i plan to go trough this once the 3.6 eats its last head and is not covered. I am not sold on this exhaust manifold cast into the head. I think that is the issue with this design. m2c
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Unread 05-06-2014, 06:49 AM   #8
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I haven't changed a plug or any sensor on the hemi, it has more than 90k on it now.
Hasn't any hiccups or other issues.

It has a high cam position which is great for cranks
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Unread 05-06-2014, 08:33 PM   #9
unobtanium
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Quote:
Originally Posted by Evildriver-3 View Post
I haven't changed a plug or any sensor on the hemi, it has more than 90k on it now.
Hasn't any hiccups or other issues.

It has a high cam position which is great for cranks
My LS1 had 0 change in plug gap at 80K miles. Pulled one and checked. Curious if your Jeep's 5.7 is still optimal? My LS1 was getting factory EPA mileage, laying down new horsepower, etc. I sold it at 149K miles with factory plugs. It was running great.
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Unread 05-06-2014, 08:45 PM   #10
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HEMIs are great motors...but LS are extremely more stout and are a lot easier to get HP out of.....my 04 silverado 5.3L has 209K and those were hard miles with my lead foot and all ive changed is a water pump and that was only because the gaskets were leaking....all you really need to get decent power out of an LS is a good cam and heads...and it will move.
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Unread 05-06-2014, 09:57 PM   #11
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Quote:
Originally Posted by unobtanium View Post
My LS1 had 0 change in plug gap at 80K miles. Pulled one and checked. Curious if your Jeep's 5.7 is still optimal? My LS1 was getting factory EPA mileage, laying down new horsepower, etc. I sold it at 149K miles with factory plugs. It was running great.
Never touched the plugs.

Change the oil every 10k or so, oil filter every 4k, changed the air filter twice.
Brake a few times and tires.
.
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Unread 05-07-2014, 07:43 PM   #12
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The Hemis and LS motors have the same ups and downs. More expensive to service, and more vulnerable to poor maintenance than the older motors. They'll go a long ways taken care of without many needs for several hundred thousand miles- and if they are seriously neglected they'll be NFG in a few tens of thousands of miles.

5.7s make poor swap candidates because they're expensive, and very few are any good. For the small bump in price that it usually is over a good 5.7, I really think the 6.1 is a better swap candidate. The 4.7 isn't a terrible candidate for a swap either- they're a good driver motor that's gotten cheap compared to Hemis and use Hemi transmissions.

The trans and gears have a lot to do with mpg. The Dodge transmission is more conducive to cruising around 50mph, and work much better when you beat on 'em at low speed. Very few of the Dodge combos are setup for cruising at highway speed anymore- a lot more of the Chevies have tall gears for highway cruising.
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Unread 05-09-2014, 03:49 PM   #13
unobtanium
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Quote:
Originally Posted by BrokeWJ View Post
The Hemis and LS motors have the same ups and downs. More expensive to service Huh? My LS1 required no service. Literally. Oil and air filters are the same as the have always been..., and more vulnerable to poor maintenance than the older motors. Howso? I have owned an LT1, also. IT was vulnerable with that optispark. They'll go a long ways taken care of without many needs for several hundred thousand miles- and if they are seriously neglected they'll be NFG in a few tens of thousands of miles. Yeah, most motors are if you refuse to change the oil and the pan runs dry or something.

5.7s make poor swap candidates because they're expensive, and very few are any good. What do you mean? Unless the pushrods are bent on the bearings spun, LS1's are typically "good". For the small bump in price that it usually is over a good 5.7, I really think the 6.1 is a better swap candidate. The 4.7 isn't a terrible candidate for a swap either- they're a good driver motor that's gotten cheap compared to Hemis and use Hemi transmissions.

The trans and gears have a lot to do with mpg. The Dodge transmission is more conducive to cruising around 50mph, and work much better when you beat on 'em at low speed. This has not been my experience. Very few of the Dodge combos are setup for cruising at highway speed anymore- a lot more of the Chevies have tall gears for highway cruising. My LS1 F-body cruised at about 2K at 80mph. Almost identical to my Jeep. WIthin a few hundred rpm.
We seem to have had different experiences.
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Unread 05-10-2014, 03:33 PM   #14
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Quote:
Originally Posted by unobtanium View Post
We seem to have had different experiences.
Point being that a lot of the older motors you could "catch" them before they were NFG if they were poorly serviced. Most of the newer Dodge/GM motors aren't worse than the old ones- just go to the bad faster when neglected.

When I say 5.7, I'm not talking an LS1. Yes, it's also a 5.7, so is a 350, and an LT1. But I mean the 5.7 Hemi.

On the trans, I was meaning truck to truck. Chevy still does a lot of tall gear trucks whereas it's fallen out of popular Dodge form in the last 13 years. 3.55s, 3.73s, and 3.92s are much more common in Dodges than 3.2s and they don't offer the gears taller than 3.2 anymore. GM still puts the common '80s truck gears in many of their new trucks. As far as I can see, these are where the major economy differences between the Chevies, Dodges, and other Chevies are.

Thus far, it's seemed to me like I can attain my best fuel economy closer to 50 at a steady cruise, and that's around 1400. Otherwise about the best I've done is 22- I do much better on long trips than short ones. Usually run it hard enough to be about a steady 18/19 on short trips. I have an early 4.7 truck without the second OD, with 3.73s. A while back I began to realize I get probably get far better fuel economy when I try than I realize. An extra 2 mpg doesn't make for an extra 100 miles on the same amount of gas. I typically drive it down to what I think is like 5-7 gallons in the tank and fill it then when it says empty. Far from it, but what a great indicating point. I've put 40k on this truck in a few years. Seems like if I don't go the 3000 miles of a 600 mile trip, I end up going 2000 locally.

My buddy was driving an early new body 5.3 4x Tahoe and went to a 6.0 Denali AWD and where the Yukon was typically getting around 12mpg on the highway, the Denali's been closer to 16+ all around. On top of the 6.0's extra torque, it seems to be geared better to lull around both at speed and getting to it. I think the Denali has an 80e instead of a 60e- with slightly different gear ratios.

Now there is another point you're getting at, and I will certainly concede it. While the Chrysler engine electricals are sufficient and acceptable, the GM engine electricals seem to be far better and more trouble-free. But the basics of the Chrysler electricals seem to be solid overall and the total failure issues rare.
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Unread 05-11-2014, 02:46 AM   #15
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You've got me at a loss. My total gm experience is fbodies and corvettes. The drive lines in both since 1997 and 1998 have been the stuff of legend (except the 7.5 rear end...but that's not the topic). All gm engines now days are ls based in the v8 variety I believe. It's just...A mechanical tour de force.
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