This time for sure: 2012 Wrangler gets Pentastar V6, 5 speed auto

[Super mud]

Screw this I'll just stroke my 4.0 and bump up the compression then be hanging with the Hemi in the 350lb ft range lol.
Actually after looking at those graphs the 3.8 suprisingly makes torque soon. Though some simple mods on the detuned 4.0 would crap on the 3.8s torque curve.
Also I would have to agree the 4.0 at 3k does sound like it's reving to the moon but alot of xj guys feel it revs fine and gear their rigs to the upper rpm ranges. Also I think it may have to do with the perception from the sound deadening and isolation the motor you get in a jk. But v6s will rev easier and higher. My v6 explorer friend freaked when he saw my tach around 1200rpm while cruising up a hill.
This makes me want to go test drive a jk now

 

[JPK]

Years ago I had a couple of the smaller square Cherokees in succession, which I think are the XJ's, and I have to say that the 4.0 in those Jeeps didn't sound like it was going to blow past 3k rpms like the TJ/LJ's 4.0 does. Different cam and/or intake?

For a complete JK experience, I'd suggest a test drive an '11 with the 3.8 and a '12 with the Pentastar 3.6. The '12 will hit the dealer showrooms in a month or two. The 3.6 looks like it will be a substantial improvement but the five speed is an equally or more important improvement, imo. Also try a manual vs. the auto... I'm looking forward to the test drives myself.

On stroking the 4.0 to 4.6l or 4.7l, I've heard first and second hand reports which are all but opposite regarding the end results. One fellow I know loves his Golen 4.6l and tells me that it transformed his LJ. Others say, "not worth the trouble or expense." I wonder if the differring reports might be the results of one pleased-with-the-results fellow doing all of the suggested modifications, like injectors, etc, and another not-so-pleased fellow only doing the minimal and skipping the exhaust and injector mods.

I have an LJ as well as a JKU. The LJ's ride compared to the JKU doesn't warrant the stroker, imo. But if I replaced my OME suspension with an AEV/Nth Degree long arm, then maybe - but that ain't happinin.

JPK

 

[Hawkz]

One thought on the 4.0, I recently installed an Airaid cold air intake on my 2003 TJ and it made a huge difference. It feels more powerful, I am getting better mpg and the engine seems smoother at higher rpms. This is seat of the pants, except the mpg, but it is something to consider. The stock air box inlet is very restrictive by design to keep water out, but I'm sure it affects air flow as well. I'm not a fan of deep water, so I'm not worried about using the cold air intake. The intake is still above the fender, so it isn't going to be sucking water from down low. I considered a snorkle but didn't like any until I saw the new River Raider setup...

The stock XJ air box may have better air flow...

 

[Metcalf]

The new auto is NOT the 545 that is used behind the hemi. The 'new' auto is the W5A580. The gear ratios are...

3.59, 2.19, 1.41, 1.00, 0.83

Note the DEEP 1st gear....
Note the close 5th overdrive....

The axle gearing on most of the Pentastar applications so far has been VERY tall with this new auto. The GC has 3.07 gears stock with a 30.5" tall tire.

The gearing for the wrangler is going to change a LOT with the new auto.

The Rubicon package now lists 4.10's as an OPTION with the automatic. If the math works out, 4.10 gears with the pentastar/5spd auto combo might work out well for 35-37" tires with the new short overdrive. I would be hesitant to run this gearing, but it would be 'free' to try in the Rubicon.

 

[jomobco]

Incorrect. That's exactly what I want. Called "torque rise."



Which brings us back to the beginning of this topic. Not trying to be obtuse here, I just like my engines with old-school truck characteristics.

You want a diesel. Or at least you're describing one.

 

[jomobco]

The new auto is NOT the 545 that is used behind the hemi. The 'new' auto is the W5A580. The gear ratios are...

3.59, 2.19, 1.41, 1.00, 0.83

Note the DEEP 1st gear....
Note the close 5th overdrive....

The axle gearing on most of the Pentastar applications so far has been VERY tall with this new auto. The GC has 3.07 gears stock with a 30.5" tall tire.

The gearing for the wrangler is going to change a LOT with the new auto.

The Rubicon package now lists 4.10's as an OPTION with the automatic. If the math works out, 4.10 gears with the pentastar/5spd auto combo might work out well for 35-37" tires with the new short overdrive. I would be hesitant to run this gearing, but it would be 'free' to try in the Rubicon.

Gear Ratios: 545RFE versus A580 for comparison with what the hemi trucks run
1st 3.00:1 / 3.59
2nd 1.67:1 / 2.19
2nd Prime 1.50:1 / 1.41
3rd 1.00:1 / 1.41
4th 0.75:1 / 1.0
5th 0.67:1 / .83

I see your point. What's stock on the rubi auto 3.73? And what is an X or Sahara gearing? Time to do some calculations with 35's/37's and highway RPM's and see where it sits. Also I'd look at where peak torque numbers come in on the 3.6. I'm gonna drive one of these when they come out. I'm dying to know how the extra gear and the new motor effect the 4 door. :roost:

 

[Pskhaat]

You want a diesel. Or at least you're describing one.

 

[Metcalf]

Gear Ratios: 545RFE versus A580 for comparison with what the hemi trucks run
1st 3.00:1 / 3.59
2nd 1.67:1 / 2.19
2nd Prime 1.50:1 / 1.41
3rd 1.00:1 / 1.41
4th 0.75:1 / 1.0
5th 0.67:1 / .83

I see your point. What's stock on the rubi auto 3.73? And what is an X or Sahara gearing? Time to do some calculations with 35's/37's and highway RPM's and see where it sits. Also I'd look at where peak torque numbers come in on the 3.6. I'm gonna drive one of these when they come out. I'm dying to know how the extra gear and the new motor effect the 4 door. :roost:

From what I understand the Rubicon auto will come stock with 3.73 or taller gears. The 4.10 gears are a no cost option.

The option sheet shows 3.73 gears as an option for other models, so I think they some with 3.4X or 3.2X gears stock.

Working the math from the stock gearing on the grand cherokee with this engine trans combo, the optional 4.10 gears should be pretty decent for 35s ( or maybe even 37s! ). The final drive gearing places a 4.10/5spd auto combo right between the old 4spd auto with 4.88s/5.13s.

Will this be the diesel or the hemi most people really want....NO. Will this be a pretty dang decent 2door engine/transmission...PROBABLY. I hope they totally didn't mess up the automatic programming. The new automatic has some promise for sure.

Also of interest. The new 5spd auto has such a deep 1st gear that with a 2.72 t-case it is almost as low as the old 4spd auto with 4:1 transfer case. I kinda wish they would offer a 2.72 t-case in the Rubicon with 4.10 gears. I think that would be a GREAT off the shelf factory combo for 35" tires. I think it would be a lot more flexible than the 4:1 in the transfer case. With a 2.72 low you would still have a VERY decent crawl ratio with the new deep 1st gear auto, but be able to do something like 50-60mph in low range depending on tire size. The new 6400rpm redline helps that also!

 

[Stumpalump]

I got a company van with that motor in it last month. It's stronger than the old V6 but it makes it's power with a variable speed cam. It runs ok untill you hit about 4000 RPM then you feel the cam kick in and it goes. Basically for normal driving it still bogs and downshifts untill you wind it out and get the cams to move. Don't expect a miracle out of it because it's still a V-6. In the light caravan it goes like a bat out of hell but then again the old V-6 pushed those light vans real nice as well. In a 4 door jacked up JK....You still will be wanting a V-8.

 

[The Swiss]

I spent the last two days with a Dodge Charger with the Pentastar engine as rental car. This engine seams to be a kind of a mixed bag.

• Nope, it does not feel very powerful. No spectacular acceleration; no raw power; no chirping tires (obviously with the Nannie disabled). Kinda disappointing
• However, the vehicle is quick, you hit 80mph in absolutely no time. The engine accelerates and does it's job very discretely.
• Fuel mileage appears to be good. According to the dash display, I ended up with 29.3 mpg, which might be a "real" 26 mpg. Not bad for the way I was driving it.

I think I will go to the Jeep Dealership to take a Grand Cherokee for a spin to see how the Pentastar performs there.

 

[ExpoMike]

So there must be something definitely coming in the 2011 Wrangers. I just saw a TV ad last night that had Wrangler Unlimited Rubicon down to under $33,000! They even said they had 5 at that price. I was amazed as I hadn't seen one really under $38,000 on any lots in the area. Sounds like they are clearing out inventory for an upcoming change.

Be interesting to see if this new engine change will make a difference in the complaints of no power.

 

[JPR4LFE]

I am in the market for a used Unlimited, but I am holding out until the new engine comes out. I guess we will know shortly, but how likely is it that the price of an 07 may come down if this new engine is all its cracked up to be? Any predicitons? It also seems that some of the owners of early Jk's could be ready for an upgrade and I would guess a new engine would be a perfect excuse!

 

[The Swiss]

Placed my order for a 2012 JKU Rubicon this morning :wings:

 

[Carolyn]

A few dealers around the country have 1. Or 2. Several members of a Jeep Forum have taken possession, and quite a few are taking delivery within the week...

Meanwhile, I'm quite happy driving my '11 :sombrero: