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Topic Review (Newest First)
06-07-2011 06:44 PM
Sherpa
Quote:
Originally Posted by Ibuildembig View Post
I agree with your logic but 800 pounds is nothing when you start modding one.
You got that right! I wonder how much weight I've already added with my rocker guards, f&r bumpers, steering box and diff skid plates, etc... and I'm not done modding yet (of course).
06-07-2011 09:28 AM
jkaufman_95
Quote:
Originally Posted by Ibuildembig

I agree with your logic but 800 pounds is nothing when you start modding one. I would bet that my dads YJ that I just built weighs as much or more than my sis's stock 11 rubi 4door. Might have to run to the scales and have a look see
I agree. The weight adds up. I just run over to the grain elevator and weigh it at night haha
06-07-2011 09:25 AM
Ibuildembig
Quote:
Originally Posted by Sherpa View Post
I've seen a number of people complain about how a 3.8L Wrangler doesn't get any better fuel economy than a 4.0L Wrangler, despite Chrysler's (correct) claim that the 3.8L is a more efficient engine. What people are always forgetting, though, is that a 4dr JK weighs about 800 pounds more than a TJ. That is a very significant difference. If you swapped a 4.0L into a 4dr JK, it would get worse mileage than with the stock 3.8L engine. Similarly, if you threw an 800 lb chunk of lead in the back seat of a TJ, its fuel mileage would plummet.
I agree with your logic but 800 pounds is nothing when you start modding one. I would bet that my dads YJ that I just built weighs as much or more than my sis's stock 11 rubi 4door. Might have to run to the scales and have a look see
06-07-2011 06:26 AM
daggo66
Quote:
Originally Posted by Irongrave View Post
I've run both the 4.0 is a better motor hands down. Simple effective nearly bullet proof I've pushed 2 close the 200k mark with just oil changes and spark plugs and a sensor here or there. our WK with the 3.8 has been in the shop already for a few minor motor related issues and its a lot harder to work on.
Are you sure? I thought the WK had the 4.0 V6, same as the Pacifica.
06-07-2011 01:07 AM
Northwest4x4 Sorry to bash anyone who bought a JK wasn't trying to start drama was just saying it how it is...

To the guy who posted this check out this writeup of the 2006 rubicon vs 2007 rubicon it's a good write-up if you are seriously considering the differances.

Richard’s Ramblings » 2006 vs 2007 Jeep Rubicon…
06-07-2011 01:02 AM
Northwest4x4 4.0's are a legendary motor. Better than the 3.8. Any straight six platform is bombproof look at the 4.0, Cummins series straight six that competes with v8 diesels, the old Ford 300 Inline six, all were amazing motors i'm sure there are more but those are the ones I have experienced in my life.

I hate the new jeep's they are pretty much 4x4 minivans, hell same motor they use in there minivans. The 4 door's aren't a jeep more like a suv jeep like the cherokee haha, if you do decide to get a 07-newer at least get the 2 door JK It's the last of the "real jeep LOOK" on the outside atleast, The Tj 4.0's were the last "REAL Jeep."
06-07-2011 12:05 AM
Matcheen This agrument sucks! Isn't everybody tired of it? What about the 4.2? Put a Motorcraft carb in it and...lmfao
06-06-2011 11:31 PM
Kevin I have an 08 JK4-dr Sahara (V-6) and a 98 TJ 4.0. Both Auto's. Just drove the TJ to leave it at the cabin for the summer and @65-70 mph I got a little better than 15 mpg. My Sahara will give me 19 or better on cruise @ those speeds. I have no complaints on the operation of either of them although I just expect them to turn on and if I'm going off-roading they do what's expected of them......So far!
06-06-2011 09:20 PM
Irongrave I've run both the 4.0 is a better motor hands down. Simple effective nearly bullet proof I've pushed 2 close the 200k mark with just oil changes and spark plugs and a sensor here or there. our WK with the 3.8 has been in the shop already for a few minor motor related issues and its a lot harder to work on.
06-06-2011 08:59 PM
Sherpa
Quote:
Originally Posted by Ibuildembig View Post
my sis's 3.8 is no better [at fuel economy] than any of our other 4.0's so I dont get that...hmmmm
I've seen a number of people complain about how a 3.8L Wrangler doesn't get any better fuel economy than a 4.0L Wrangler, despite Chrysler's (correct) claim that the 3.8L is a more efficient engine. What people are always forgetting, though, is that a 4dr JK weighs about 800 pounds more than a TJ. That is a very significant difference. If you swapped a 4.0L into a 4dr JK, it would get worse mileage than with the stock 3.8L engine. Similarly, if you threw an 800 lb chunk of lead in the back seat of a TJ, its fuel mileage would plummet.

Having said all that, the single biggest reason the 4.0L was discontinued was the fact that it wasn't clean enough to meet new Federal emissions mandates. Chrysler looked at cleaning it up, but the cost of doing so was prohibitive... especially when they already had a current engine of similar power output that was sufficiently clean.

Don't forget one other interesting tidbit in support of the 3.8L V6: the fact that Chrysler used it instead of the 3.7L V6 which was/is used in other RWD applications and even other 4WD Jeeps. It would have made more sense from a marketing standpoint to simply switch from the 4.0L I6 to the 3.7L V6, but Chrysler choose not to do so since the 3.7L V6 does not make as much low-end torque as the 4.0L did. The 3.8L, however, does.
06-06-2011 08:48 PM
Sherpa
Quote:
Originally Posted by Ibuildembig View Post
my bet is that it was such a proven motor they had to dump it because they were not selling parts.
They weren't selling parts? You're saying Chrysler dumped the 4.0L engine because it didn't have enough designed-in failure points? That is the funniest thing I have read all year.

06-06-2011 08:17 PM
KBR97
Quote:
Originally Posted by MTH View Post
It's funny, there's folks here that claim the opposite--that they have both (or had one and now another) and they prefer the 3.8. My brother drives a 4.0 and loves driving my dad's 3.8, which he prefers in every respect.
Yeah, I think unless your actually driving both regularly on a day to day basis you can't properly compare. The opinion will usually be biased in some way or another. Whatever feels good at the moment.
I bet your brother loves driving your dads 3.8 because its something "new", it feels fresh, different.
06-06-2011 06:14 PM
MTH
Quote:
Originally Posted by KBR97 View Post
4.0
I like the lower end power the 4.0 has compared to the higher revving 3.8.
I have both, and I have been driving both regularly. The 3.8 is a decent little engine, besides a lot of them have oil burning issues, mine included. I dont think it has any business in a Jeep Wrangler though.
It's funny, there's folks here that claim the opposite--that they have both (or had one and now another) and they prefer the 3.8. My brother drives a 4.0 and loves driving my dad's 3.8, which he prefers in every respect. I'm not sure what I'd prefer given that I really haven't had the opportunity to drive the 4.0 much.

Well OP, there you have it. Drive'em both and see what you want to do. As long as you're happy with it, you'll be in good company.
06-06-2011 05:21 PM
6InARowMakesItGo
Quote:
Originally Posted by MississippiGrizz View Post
I am looking at buying my first jeep. Any advantage of going with the older 4.0L versus the newer 3.8L engine? I have heard how dpendable the 4.0 is but I assume they would have improved it with the 3.8L.
Also, has handling, safety, etc improved with the newer models? I am looking at years 2003-2009.
Thanks for any input.
by the way what kind of price range are you looking at as that can make a difference in what you look for.
06-06-2011 05:17 PM
KBR97 4.0
I like the lower end power the 4.0 has compared to the higher revving 3.8.
I have both, and I have been driving both regularly. The 3.8 is a decent little engine, besides a lot of them have oil burning issues, mine included. I dont think it has any business in a Jeep Wrangler though.

My opinion on the 3.8 is that Jeep/chrysler needed something...anything to put in the new JK's and figured what the hell, lets throw this turd in there and wait till the pentastar or something better is ready to be introduced. It was something just to get them buy for a few years. This is not a fact at all...just something I was thinking once.
06-06-2011 05:16 PM
6InARowMakesItGo
Quote:
Originally Posted by MTH View Post
Okay . . . flaked out on you guys for a little while there. I see everyone's been busy.

All I'm saying about the dynos is a simple law of averages type analysis, nothing deep. Overall, the 3.8 dynos out there look about the same, as do the 4.0 dynos. Sure they vary some, but, overall, just about every 4.0 dyno is within a few digits of every other 4.0 dyno. Same for the 3.8.

So, if you put your mind to it, you could average each group and come with an "average" dyno pull for each engine. Just doing that roughly in my head based on the dynos I've seen, I don't see much more low end "usable torque" in the 4.0.

By contrast, if we compared the average 3.8 dyno numbers to those produced by a good diesel engine, do you think we'd see a large swing in low end torque? Of course. And while it would be true that the 3.8 dynos and the diesel dynos were not done under precisely the same atmospheric conditions etc., the swing would be so broad that it would nevertheless be safe to conclude that the diesel in fact produces much more torque.

Based on the dynos I've seen, I feel comfortable concluding that the two engines put out similar amounts of low end torque. Based on engine design, I'd expect the 4.0 probably has more and I've seen dynos showing it, but I've never seen a dyno showing the type of large discrepancy one would think exists to warrant zillions of forum posts on the topic of superior "usable torque."

Is that some sort of rock solid analysis that affirmatively establishes exact numbers? Of course not. It's just a generality. But it does indicate that, regardless of the specific conditions (atmosphere etc.), the two engines are reasonably close. In my view, they're close enough that it doesn't really make sense to go on and on about more "usable torque" in the 4.0, similar to how it doesn't make sense to rave about the 3.8 having more "usable horsepower." If the difference was really wide and broad, then we would see a consistently larger spread in dyno after dyno--as would be the case if we ran either engine against a good diesel.

And finally . . . I am NOT claiming the 3.8 is some kind of fabulous, great engine. It's a good engine. Reliable and easily/cheaply repaired. Though I do think Jeep goofed on the throttle and gearing, which (I would argue) is what produces the "butt dyno" effect that leads folks to assert that the 4.0 has more "usable torque." But everything I've seen indicates that it's mostly an illusion.
yep i totally understand all your points but i'm still not convinced. i guess we will just have to agree to disagree and that's ok.
06-06-2011 05:08 PM
MTH Okay . . . flaked out on you guys for a little while there. I see everyone's been busy.

All I'm saying about the dynos is a simple law of averages type analysis, nothing deep. Overall, the 3.8 dynos out there look about the same, as do the 4.0 dynos. Sure they vary some, but, overall, just about every 4.0 dyno is within a few digits of every other 4.0 dyno. Same for the 3.8.

So, if you put your mind to it, you could average each group and come with an "average" dyno pull for each engine. Just doing that roughly in my head based on the dynos I've seen, I don't see much more low end "usable torque" in the 4.0.

By contrast, if we compared the average 3.8 dyno numbers to those produced by a good diesel engine, do you think we'd see a large swing in low end torque? Of course. And while it would be true that the 3.8 dynos and the diesel dynos were not done under precisely the same atmospheric conditions etc., the swing would be so broad that it would nevertheless be safe to conclude that the diesel in fact produces much more torque.

Based on the dynos I've seen, I feel comfortable concluding that the two engines put out similar amounts of low end torque. Based on engine design, I'd expect the 4.0 probably has more and I've seen dynos showing it, but I've never seen a dyno showing the type of large discrepancy one would think exists to warrant zillions of forum posts on the topic of superior "usable torque."

Is that some sort of rock solid analysis that affirmatively establishes exact numbers? Of course not. It's just a generality. But it does indicate that, regardless of the specific conditions (atmosphere etc.), the two engines are reasonably close. In my view, they're close enough that it doesn't really make sense to go on and on about more "usable torque" in the 4.0, similar to how it doesn't make sense to rave about the 3.8 having more "usable horsepower." If the difference was really wide and broad, then we would see a consistently larger spread in dyno after dyno--as would be the case if we ran either engine against a good diesel.

And finally . . . I am NOT claiming the 3.8 is some kind of fabulous, great engine. It's a good engine. Reliable and easily/cheaply repaired. Though I do think Jeep goofed on the throttle and gearing, which (I would argue) is what produces the "butt dyno" effect that leads folks to assert that the 4.0 has more "usable torque." But everything I've seen indicates that it's mostly an illusion.
06-06-2011 03:53 PM
6InARowMakesItGo
Quote:
Originally Posted by Ibuildembig View Post
my sis's 3.8 is no better than any of our other 4.0's so I dont get that...hmmmm
well it don't really know. i'm only guessing. i just figured it was because the new emissions and mpg regulations. wether it worked or not i guess is a different story.
06-06-2011 03:43 PM
Ibuildembig my sis's 3.8 is no better than any of our other 4.0's so I dont get that...hmmmm
06-06-2011 03:36 PM
6InARowMakesItGo
Quote:
Originally Posted by LaTuFu View Post
The same reason they dumped the 4.0L after years in the fleet. They came up with something different.
Quote:
Originally Posted by Ibuildembig View Post
Doubtful...my bet is that it was such a proven motor they had to dump it because they were not selling parts. Since dodge didnt design it anyway, they had to use one of their own engines.
it was the fuel mileage. that's my take on it anyway.
06-06-2011 03:32 PM
Ibuildembig
Quote:
Originally Posted by LaTuFu View Post
The same reason they dumped the 4.0L after years in the fleet. They came up with something different.
Doubtful...my bet is that it was such a proven motor they had to dump it because they were not selling parts. Since dodge didnt design it anyway, they had to use one of their own engines.
06-06-2011 03:31 PM
SirGeorgeKillian
Quote:
Originally Posted by LaTuFu View Post
The same reason they dumped the 4.0L after years in the fleet. They came up with something different.

You gotta remember that at the corporate level there are bigger factors that decide what engine gets picked than which one is the "better" engine....
06-06-2011 03:29 PM
6InARowMakesItGo
Quote:
Originally Posted by El Gringo View Post
I'm pretty sure that everyday driving is more important than dynos. If you don't live on the dyno, then you are out driving around and that's where the numbers matter.
if you don't want to talk about the dynos then you don't have to, but i'm enjoying discussing with MTH about it.
06-06-2011 03:28 PM
LaTuFu The same reason they dumped the 4.0L after years in the fleet. They came up with something different.
06-06-2011 03:27 PM
El Gringo
Quote:
Originally Posted by 6inarowmakesitgo View Post
i just re read my last post and confused myself. what i mean is jeeps aren't powerful enough to notice the big differences in dynos. a 5hp difference in two jeep dynos will be amplified when a much more powerful car is dynoed. that is why two tests can be misleading.
Yes, I will agree with this. In a jeep it does not make a whole lot difference. percentage or otherwise, they aren't aerodynamic enough and not built to such tight tolerances. I would assume no one bought their jeep because 'it was so fast!'
06-06-2011 03:25 PM
El Gringo
Quote:
Originally Posted by 6inarowmakesitgo View Post
no its not if your talking about comparing dynos. in fact its very relivant. we're not talking about everyday driving, we're talking about dynos.
I'm pretty sure that everyday driving is more important than dynos. If you don't live on the dyno, then you are out driving around and that's where the numbers matter.
06-06-2011 03:22 PM
6InARowMakesItGo
Quote:
Originally Posted by El Gringo View Post
So all jeeps are driven in the same exact conditions (barometric pressure, altitude, temperature, humidity, engine temp, trans temp, intake temp, oil quality etc.)? If not, than this argument is completely null.
no its not if your talking about comparing dynos. in fact its very relivant. we're not talking about everyday driving, we're talking about dynos.
06-06-2011 03:20 PM
6InARowMakesItGo i just re read my last post and confused myself. what i mean is jeeps aren't powerful enough to notice the big differences in dynos. a 5hp difference in two jeep dynos will be amplified when a much more powerful car is dynoed. that is why two tests can be misleading.
06-06-2011 03:20 PM
Ibuildembig Here's something to chew on.....if the 3.8 is such a good engine, how come dodge is dumping it this year after 5 years in a wrangler?
06-06-2011 03:18 PM
El Gringo
Quote:
Originally Posted by 6inarowmakesitgo View Post
so let me see if i can wrap my head around what you're saying.

if jeep A makes 150hp on dyno A on day A at location A

and jeep B makes 145hp on dyno B on day B at location B

assuming they were set up the same, like same engine, trans, gears, everything.

do you assume two muscle cars will do the same thing?

example

camaro A makes 600hp on dyno A on day A at location A

and camaro B makes 595hp on dyno B on day B at location B
the above is all a question i ask to understand your thought on how dynos work.


but this is not how it works. it will be a percentage less on dyno B vs A. altitude, humidity and alot of other factors go into what a dyno result wil be. thats why it has to be on the same day on the same dyno in the same place. it may not be much but it's enough to say that the results aren't certain. i do see what you mean and im really just starting conversation. i don't think there is anything wrong with the 3.8 or that its weak. i don't think the 4.0 is some invincible all powerful engine. but the fact that i have a 4.0 and you have a 3.8 makes both of out opinions bias.
So all jeeps are driven in the same exact conditions (barometric pressure, altitude, temperature, humidity, engine temp, trans temp, intake temp, oil quality etc.)? If not, than this argument is completely null.
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