[Flipside]

By dyna: in line 6`es run 7 main bearings, V`s only 5?

Yep, more bearings in the I6 = more strength. Also, the crankshaft has more mass - makes it harder to stall, but also harder to spin up.

BTW - ever notice that most commercial / industrial motors are In lines? Nuff said.

[abstractjeep]

Originally Posted by Flipside

BTW - ever notice that most commercial / industrial motors are In lines? Nuff said.

not only them, but also higher-end car manufacturers like BMW and Mercedes like to use inlines in their cars. They are a very reliable and strong design.

[monger]

I6 is the most balanced engine design. not sure of the physics behind it all, but the firing order of an I6 makes it the "smoothest"

[Jerry Bransford]

Originally Posted by SecondTJ

the 3.8 produces more hp and torque overall, but the I6 has more low end grunt.

Translated, that just says the I6 still has more low-end torque where it is most useful in a Jeep. The V6 only produces its greater torque at far higher RPMs than are useful for most low-speed offroading applications. Jeep is real careful to avoid showing torque curves comparing the two engines side-by-side. Here they are though, notice how much flatter the torque curve is for the I6 down to 1200 RPMs and how they don't even show the torque for the V6 below 2200 RPMs. The curve indicates to me that the torque falls off dramatically on the V6 at RPMs below 2200 RPMs, unlike the I6!

[BlueFlame]

Originally Posted by SecondTJ

the 3.8 produces more hp and torque overall, but the I6 has more low end grunt.

Gas mileage? they are same practically, the V6 gets slightly better mileager.

for 5-speed I6= 16/19, 6-speed V6= 17/19

Yeah, you have to look at the graphs of the torque and hp curves.
The 3.8 doesn't produce nearly as much of either across as broad a range, hence in real world driving it feels (and is) less powerful. This will usually be true comparing any I6 to a comparable V-anything. I6 is inherently a torque maker.

(edit) way ta go Jerry! (that'll teach me to reply before finishing the thread...) Another good example is the old Dakota V6 compared to say the Toyota 3,0 V6. 170hp v 150hp but it the real world the Yota motor pulled harder and was much more satifying to drive. Why? broad power - more down low where it gets used.

But I really don't understand why the new V6 doesn't get better mileage, one would think that would be the main reason they went with the newer designed engine. Perhaps those curves explain it - it's a bit underpowered in the application, and has to use more fuel to move the jeep unless you rev the heck out of it, but then that takes more fuel too...

[Jeepinty]

Originally Posted by Jerry Bransford

Translated, that just says the I6 still has more low-end torque where it is most useful in a Jeep. The V6 only produces its greater torque at far higher RPMs than are useful for most low-speed offroading applications. Jeep is real careful to avoid showing torque curves comparing the two engines side-by-side. Here they are though...

BINGO

[The_'ster]

Originally Posted by BlueFlame

But I really don't understand why the new V6 doesn't get better mileage, one would think that would be the main reason they went with the newer designed engine. Perhaps those curves explain it - it's a bit underpowered in the application, and has to use more fuel to move the jeep unless you rev the heck out of it, but then that takes more fuel too...

It cost too much to keep the tooling and keep making the 4.0 for just one vehicle, when they can put the v6 in all sorts of vehicles and reduce cost of manufacturing.

[SecondTJ]

Originally Posted by BlueFlame

Yeah, you have to look at the graphs of the torque and hp curves.
The 3.8 doesn't produce nearly as much of either across as broad a range, hence in real world driving it feels (and is) less powerful. This will usually be true comparing any I6 to a comparable V-anything. I6 is inherently a torque maker.

But I really don't understand why the new V6 doesn't get better mileage, one

Yea i know, the I6 produces 85% of its torque at idle, thats damn impressive. And thats a great graph Jerry!

I think the JK weighing an extra 300 lbs also has something to do with the gas mileage

[mdm]

Originally Posted by The_'ster

It cost too much to keep the tooling and keep making the 4.0 for just one vehicle, when they can put the v6 in all sorts of vehicles and reduce cost of manufacturing.

The reason behind dropping the I6 for the US market is emissions requirements. They have gone as far as they can with the I6. It is my understanding that the I6 will still be installed in export models.

[jonzer12]

Too much empahsis is being placed on the fact that toque is built by the inline configuration. Bore, Stroke and Cam have a far greater impact. It would be incorrect to state the 4L has more torque solely due to the fact that it is an inline motor vs "V". You can engineer a V6 for a very flat torque curve. Don't forget also that not all "V" motors use the same degree of cylinder bank. The character of a motor can be changed dramatically simply by changing the camshaft(s)

[jkirkku]

Serious power became an option in 1987 when Jeep dumped the 2.8 V6 and put a stout, 4.0-liter, inline six-cylinder engine of Jeep's design on the option list. K

-From A cherokee website

So for the smart comments.... thats 19 years in a jeep which is almost 20 which is what I said! I said Jeep not wrangler.

And as far as the difference, that site tells you that if they are exactly the same specs wise they will perform the same. These engines don't have the same specs except the 6 cylinders. This v-6 has a lot of potential (not just because it's v over I) because it's new and could possibly get good after market support(especially if its that similar to other DC V6s'. But let's be honest, the majority of us on here havent put cams or a stroker kit, or anything like that on our motors. So in this case the I-6 is better to start with. But I do agree that it is possible to build a v6 to be useful offroad.

[beryl]

Originally Posted by dyna

Ditto, I dont want no stinking mini van engine in my jeep.

x2 hahahaha

[dieselcrackel]

I will take my inline 6 anyday of the week..... Too bad D.C. couldn't put those slant 6 cylinders they made years ago in a jeep . That was another die hard engine. Seems to me all manufactures eventually screw with a good thing!

[lupien]

One more thing is that the I6 is a narrower engine then the V6. That means the there is less weight on the sides of the Jeep which helps reduce body roll or even fliping over.

[ChrisMan]

Talk about great answers to my question, thanks!