wanderer-rrorc
Explorer
I had a 2dr with the auto,....guttless...soft-top soft doors...
the 4dr with the 6spd...love it!!!
the 4dr with the 6spd...love it!!!
Why the JK 3.8L V6 sucks.....the video!!
- Thread starter Cole
- Start date
Pskhaat
2005 Expedition Trophy Champion
Variable cam's pretty difficult without block re-design. Though I agree it is a dated design I'm not all that confident the 4.0 couldn't be engineered out the gate to meet emissions.
Objectively, the V6 could be rated with some very similar characteristics, and the supply chain could be simplified. Not bad or good, just my speculation as to the decisions made, but I speculate much better at GM and Ford than old Chrysler.
:cheers:
Root Moose
Expedition Leader
I think the 4.0 could have had more life in it if it utilized a cross-flow head.
Changing the head pretty much means a full re-engineer again.
Changing the head pretty much means a full re-engineer again.
TheMike
Adventurer
Since this thread made me want to film a comparative video, I'm putting it here.
WHO: my family and I returning from EJS
WHAT: my 6.1 JK pulling a totally packed and loaded Chaser trailer
WHEN: 4/3/10
WHERE: Dillon to the Eisenhower tunnel.
WHY: because it was done with the 3.8.
Remember, it was busy traffic, snowing, and I was HEAVY (8000lbs)! Here is the setup as I pulled into the house.
THE VIDEO:
http://www.youtube.com/watch?v=YFKSj4LPlOs&feature=youtube_gdata
WHO: my family and I returning from EJS
WHAT: my 6.1 JK pulling a totally packed and loaded Chaser trailer
WHEN: 4/3/10
WHERE: Dillon to the Eisenhower tunnel.
WHY: because it was done with the 3.8.
Remember, it was busy traffic, snowing, and I was HEAVY (8000lbs)! Here is the setup as I pulled into the house.
THE VIDEO:
http://www.youtube.com/watch?v=YFKSj4LPlOs&feature=youtube_gdata
greenhorn
Adventurer
Since this thread made me want to film a comparative video, I'm putting it here.
WHO: my family and I returning from EJS
WHAT: my 6.1 JK pulling a totally packed and loaded Chaser trailer
WHEN: 4/3/10
WHERE: Dillon to the Eisenhower tunnel.
WHY: because it was done with the 3.8.
Remember, it was busy traffic, snowing, and I was HEAVY (8000lbs)! Here is the setup as I pulled into the house.
THE VIDEO:
http://www.youtube.com/watch?v=YFKSj4LPlOs&feature=youtube_gdata
Nice rig, Thanks for the video. A couple of questions from a Hemi JK dreamer. What axle ratio are you using? I under stand that you are hauling quite a load, but I was surprised to see the RPM's that high. Your using the 5 speed auto, correct? Did you have to run it out of OD the whole trip, then downshift to 3rd on the hills? Also the temp seems high for on the highway in 30 degree weather. What is normal for the hemi? does it normally run in the 240's? Thanks.
alosix
Expedition Leader
(Hoping the owner can chime in ,but here's my take)
The 545RFE is a 5 speed tranny, but IIRC tow mode only lets you into the 3rd gear (the 1-1 gear) as it has 2 OD gears in it. That would account for the RPM's he's seeing if using it that way and its geared for decent driving without the trailer on sorta flat ground.
As for temp. I'd like to hear that answer as well. Been hard for me to find the 'happy temp' for a workign Hemi. The one on my 725 gives me the willies sometimes as it will like to run 230-240. I normally back off and let it rest at that point, but I'm beginning to think this engine does like to run nice and warm.
Jason
TheMike
Adventurer
I knew someone would catch the temps 
Funny thing. This was my first trip of any consequence with the completed rig pulling the trailer. I found out that pulling the trailer up any substantial grade (long ones) it did run hot. FYI: the computer shuts down the AC when it gets up in the upper 240's. Anywho, I saw and spoke with Dan from Burnsville (provider of my self installed Hemi kit) about the temps. Right off the bat he volunteered his new and improved (40% better) radiator to replace the one that cane from the kit. No, it's not normal to get that hot. The 6.1 normally runs between 200-220. I believe it comes and is designed for a 210 thermostat.
Aside from getting a bigger/different design radiator, I have a few things that cancontribute to those higher high speed temps. Don't forget I was pulling 2200 lbs at over 9000 feet and rapidly climbing in elevation (and driving hard).
1) big light out front DOES affect the forced air flow getting naturally through the cooling system. The BOR kit is different than the AEV in the fact that the computer funs the fan based on temps versus the "all the time on" fan setup with AEV. I dont know of the computer's handeling of the fan at speeds.
2). I installed the biggest thermostaticly controlled cooler and fan setup I could find. It's automatically activated at a trans temp of 175 and the trans cooling is completely seperate to normal cooling. Meaning the stock trans cooler is part of the radiator. The Hemi conversion I run uses that stock trans cooling for just the power steering now with a independent trans cooler (hense the big one I put on in preperarion of normal higher engine temps and towing my Chaser)
forgive the pic but if you see all that stuff it can significantly block forced air flow at higher speeds:
I was concerned about cooling while offroading. No problems there. Temps stay right about 210-220 all the time idling, crawling, no matter.
When I did experience the 250 degree temps (scan guage reading and upper limit traditional temp gauge) just slowing down or stopping immediately remedied the situation. Fan alone cooling works perfectly.
Funny thing. This was my first trip of any consequence with the completed rig pulling the trailer. I found out that pulling the trailer up any substantial grade (long ones) it did run hot. FYI: the computer shuts down the AC when it gets up in the upper 240's. Anywho, I saw and spoke with Dan from Burnsville (provider of my self installed Hemi kit) about the temps. Right off the bat he volunteered his new and improved (40% better) radiator to replace the one that cane from the kit. No, it's not normal to get that hot. The 6.1 normally runs between 200-220. I believe it comes and is designed for a 210 thermostat.
Aside from getting a bigger/different design radiator, I have a few things that cancontribute to those higher high speed temps. Don't forget I was pulling 2200 lbs at over 9000 feet and rapidly climbing in elevation (and driving hard).
1) big light out front DOES affect the forced air flow getting naturally through the cooling system. The BOR kit is different than the AEV in the fact that the computer funs the fan based on temps versus the "all the time on" fan setup with AEV. I dont know of the computer's handeling of the fan at speeds.
2). I installed the biggest thermostaticly controlled cooler and fan setup I could find. It's automatically activated at a trans temp of 175 and the trans cooling is completely seperate to normal cooling. Meaning the stock trans cooler is part of the radiator. The Hemi conversion I run uses that stock trans cooling for just the power steering now with a independent trans cooler (hense the big one I put on in preperarion of normal higher engine temps and towing my Chaser)
forgive the pic but if you see all that stuff it can significantly block forced air flow at higher speeds:
I was concerned about cooling while offroading. No problems there. Temps stay right about 210-220 all the time idling, crawling, no matter.
When I did experience the 250 degree temps (scan guage reading and upper limit traditional temp gauge) just slowing down or stopping immediately remedied the situation. Fan alone cooling works perfectly.
TheMike
Adventurer
Oh yea, I played with OD on and off. No change in temps or mileage. Older type of transmissions it is important to tow with OD off. I dont think it matters much on new completely electronic transmissions. It will do what it needs to do for performane and functional protection.
I run 5:13 gears on 37's both JK and trailer. I wanted about 2500 prm at 75 so that's what I did and why.
I run 5:13 gears on 37's both JK and trailer. I wanted about 2500 prm at 75 so that's what I did and why.
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robert j. yates
Explorer
The big problem with the 4.0 and the TJ's OBDII is that there is no EGR. That required Jeep to do some rather significant dancing around with the cam and ignition profiles to get it to pass emissions. All of this not to mention that the JTec ECU programming is always pushing the Jeep to run at stoichiometric on the fuel maps which is why headers, CAI's and programmers really don't seem to work on the 4.0.
Its a tractor motor (I love mine which is why I built it up) but I think Jeep saw the writing on the wall and decided against investing anything more into it, either on the actual block and rotating assembly or OBDII/ECU side. I think the new Pentastar V6 will be a huge improvement over the minivan V6 currently in the JK (not to mention the 4.0) and its rightfully so that they invested their precious engineering resources into that motor.
TheMike
Adventurer
It's a Scan Gauge. It's a carry over from my LJ. Even though there are other digital setups out there it does almost everything I want it to do. The one exception is trans temp. That's a bummer and I wouldn't be suprised if that "programming" is made in the future.
Thunderbear
New member
I have limited sympathy for you, since I have a 4.0 with a 3spd, 3.07s and 33s.
Trifecta of death. 0-60 in 3 weeks flat. :yikes:
Trifecta of death. 0-60 in 3 weeks flat. :yikes:
alosix
Expedition Leader
I have limited sympathy for you, since I have a 4.0 with a 3spd, 3.07s and 33s.
Trifecta of death. 0-60 in 3 weeks flat. :yikes:
Man.. When mine was setup like that with 31s it was painful to drive. I couldn't imagine 33s.
I bet its fun to go down steep hills offroad.
Thunderbear
New member
I started with 31x11.50s, didn't notice anything. I drive slower than grandma anyway, so it's not a big deal to me, just the people behind me :bike_rider: When I had the Rusty's shocks on the back it was like riding a waterbed, slow and bouncing like mad.
It's been a long time since she's been off road. Last couple of times, she busted fuel lines.. twice. I'll eventually swap axles instead of regearing 35s.