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  1. #1
    JK Enthusiast Elickzer's Avatar
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    Beverly Hills, MI
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    Default 4.0 vs 3.8 vs 3.6

    3.6-liter V6 Variable Valve Timing Pentastar™ engine produces 290 horsepower at 6,400 rpm and 260 lb-ft of torque at 4,800 rpm.

    3.8-Liter V6 Sequential Multi-Port Injection engine has 202 horsepower at 5,000 rpm and 237 lb-ft of torque at 4,000 rpm .

    4.0-Liter I6 MPI 190 Horsepower at 4,600 rpm and 235 lb-ft of torque at 3,200 rpm.

    I went for a test drive in the 2011 Grand Cherokee 3.6, and I was not that impressed with the engine. So I did a little research and I do not think the 3.6 is the answer we have all been looking for. Sure it should get a little better mileage but the extra torque comes at a price, yet another 1400 and 800 rpm respectively. Really exactly how important is the horse power number being 290 at 6,400 rpm!!!

    I for one have just sold my 09 2-Door JK and I am getting a 4-Door. Either a '10 or an '11 depending on if I can find what I want. I am sure I am going to add a Ripp Super charger and be done with it. I was toying with the idea of a Hemi but 20 large is just to much to spend. After my test drive the the Grand Cherokee, which btw is amazing inside, I just don't see the engine helping a JK enough.

    Just my 2 cents. What are your thoughts?
    Last edited by Elickzer; 08-07-2010 at 07:58 PM.

  2. #2
    JK Enthusiast ARinmyJK's Avatar
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    Default

    Pentastar, smentastar. I have no intention of giving up my '08 Unlimited for another Jeep with anything short of a diesel. I do intend on getting RIPP'ed, headed, and snork'ed . Mostly likely come April.
    We must acknowledge, once and for all, that the purpose of diplomacy is to prolong a crisis
    -- Mr. Spock "The Mark of Gideon"

  3. #3
    JK Newbie oeser's Avatar
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    Default

    I think you might be right. The Pentastar doesn't seem like a big improvement and might even be a step in the wrong direction. A diesel or v8 would be sweeeet.
    2010 Black Rubi Unl., 3.5" AEV Premium lift, 5.13 gears, 18" XD RockStars, 35x12.5 Nitto Trail Grapplers, Magnaflow exhaust, K&N filter, Factory 3rd row, a bunch of other extras, Perm-a-grin on my face!!

  4. #4
    JK Super Freak
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    Default

    trouble with most of these new engines is that they are higher and higher revving.. I personally wonder about longevity of engines that need to rev so high to get their peak power / torque band...

    I think in the wrangler world people may have to look at how we regear in the future as to get higher revs for the trail...

    personally I'd like to see a transmission with a .50 overdrive ratio (similar to the T56).. and then people could start out stock with say 4.10's.. rubi would go 4.56, etc .. this way getting the torque needed for Off-roading while still maintaining the lower RPM economy for the road trip..

    we dont need to see those high end numbers.. we need to see a DYNO chart for a stock version of each of those engines to see what they do at 1500 RPM not 6000 RPM.

    the V V T has the potential to help out on the lower end depending on how chrysler programs it... or someone else in the aftermarket programs it..

    -Christopher
    Current:
    13 2 dr sport S pwr,connect,sirius,6 spd!!
    Memories:
    76 Cherokee - Rusty (sold)
    97 TJ Sahara - Rocked, Sanded, Mudded, Snowed, Sunk
    00 TJ Sport - Mudded, Snowed, rolled in a snow drift no damage
    02 TJ Sport - Mudded a little (sold)
    06 TJ Golden eagle - Mudded a tad not enough cargo room
    08 JK 4 dr X red rock - Never Wheeled
    09 JK X 4 door Blk 6 spd all the toys!
    10 JK Silver Sport 2 door auto,tint,sirius,infinity,pwr ,U-con,Ipod,remote start

  5. #5
    JK Freak Ario56's Avatar
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    Default

    Why not a big powerful engine, with lots of torqe and HP, but also a multi-displacement engine (doesnt fire all cylinders while at highway speeds) to save gas while cruising?
    The idea of shutting cyinders down used to scare me. but i;ve talked to people with newer trucks and they say that if it wasnt for the light on the dash they'd never know it even turned on (or off, i guess)

    With all the engineers at chrysler and all the money we "gave" them.... cough... bailout... cough... They should be able to come up with something halfway decent.
    -What I lack in caring, I make up for with apathy.
    -I'll only drive black vehicles until they make something darker.
    -I'd rather be a "JK Newbie" forever than an "H2 enthusiast" for an hour

  6. #6
    JK Freak
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    Default

    Quote Originally Posted by JeepaRoo View Post
    personally I'd like to see a transmission with a .50 overdrive ratio (similar to the T56).. and then people could start out stock with say 4.10's.. rubi would go 4.56, etc .. this way getting the torque needed for Off-roading while still maintaining the lower RPM economy for the road trip..-Christopher
    As it is now we already have to re-gear these Jeeps lower to get acceptable highway use, not to get acceptable offroad use. The Rubi is already plenty low for offroad use with stock gears in the axles, because of the 4:1 transfer case. How low of gears do you want? With a .50 OD ratio you would need something like 8.13 gears to be able to ever drive your Jeep in high gear. I think that would be an even worse transmission than the auto transmission we have now. The current auto trans has a .69 OD ratio, which is already too deep of an overdrive. With 35" tires we need at least 5.38 gears to even begin to get into an acceptable RPM range on the highway. 5.86 or 6.17 gears would be even better, but nobody makes gears that low for our axles.

    I agree with the OP though, the 3.6 will have less "perceived torque" than the engine we have now, and will not feel any more powerful. Jeep needs to get off the pot, and put a V-8 in these Wranglers. Even if it were a high priced option it would be worthwhile. Ford charges an extra $3K for the 6.2 in their Raptor. I'll bet people would pay a similar premium for a 5.7 VVT Hemi in a Wrangler.
    Last edited by MOPWR2U; 08-08-2010 at 10:08 AM.
    2014 Wrangler Sport

  7. #7
    JK Enthusiast funwthmud's Avatar
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    Default

    Quote Originally Posted by JeepaRoo View Post
    personally I'd like to see a transmission with a .50 overdrive ratio (similar to the T56).. and then people could start out stock with say 4.10's.. rubi would go 4.56, etc .. this way getting the torque needed for Off-roading while still maintaining the lower RPM economy for the road trip..-Christopher
    I would also like to see a better tranny in the jk... I think if the had a 5 or 6 speed auto that was geared different then yes we can jump out with 4.56

    my neighbor just bought a tundra and it has a 6 speed w/ 4.30 gears and a 10k towing capacity.

    So if toyota can do it Jeep surely can

  8. #8
    JK Freak Pape's Avatar
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    I don't want to be rude, but how about waiting for the product to be released before complaining.
    My Friend: (pointing to a well restored Willis) want one ?
    Me: already got a 2009 one

  9. #9
    JK Super Freak JK-Tex's Avatar
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    Default

    I traded my JK for a 2010 Xterra Off Road and may be able to offer some insight here. The Nissan's engine is a beast and is, frankly, the engine I was always hoping for in the JK. It makes its power and torque at similar points in the power band, but it makes a whole lot more of each.

    I suspect Jeep will retune the Pentastar for the Wrangler. If they don't, I agree with others that the power peaks are worryingly high for a vehicle in this class, making the engine less of an improvement than it looks at first glance.

    3.8L JK:
    202 hp @ 5,200 rpm
    237 lb/ft @ 4,000 rpm

    4.0L Xterra:
    261 hp @ 5,600 rpm
    281 lb/ft @ 4,000 rpm

    2011 Grand Cherokee Pentastar:
    290 hp @ 6,400 rpm
    260 lb/ft @ 4,800 rpm

  10. #10
    JK Freak
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    Default

    I have a Jeep, and I'm satisfied with the manual 4.1 ratio

    I wheel with the JK, I didn't buy it for racing

  11. Default JK-Forum


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