Towing 5000 lbs with Max Tow Gladiator - Use Manual?

[Zachanadandy]

The 4.0L was rated at 190 HP.

I was able to bump up the one I had in my '96 ZJ Laredo to an estimated 210 HP by opening up the intake, free flow exhaust (cat included), a throttle body spacer that 'swirrled' the air coming in, and finally, I replaced the factory 19lb/hr single point injectors with 22 lb/hr multi-point injectors from a Mustang 5.0L (Bosch injectors were direct replacements). Not only could I spank a stock Mustang GT 5.0, but I also got MUCH better fuel economy like, 22 MPG running around and just over 27 MPG on the highway. (The Mustang I spanked was pissed when I told him it was a modified 4.0L I-6 in my ZJ and not a de-badged 5.2L V-8 )

The shame is that there is little we can do with the Pentastar to coax a few more ponies out of it, short of a supercharger which the lower end cannot handle, and will grenade on you.

The only other option is to see if you could get a stealership give you the RAM 1500 tune for the 3.6L Pentastar as it's rated for 306 HP.

190hp at the crank, ~150hp on every dyno I've ever seen. As far as the 3.6L, the livernoise E85 tune adds ~35hp and 55 ftlbs, nothing to scoff at, especially when e85 is nearly half the price of 87 currently. The 1996 gc with the 4.0L was a 10.8s 0-60 vehicle. Gaining 20hp would lower that .1-.3s at best. 10.5s 0-60 is still painfully slow by modern standards.

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[ChrisNLA]

Well since a friend left this 20' trailer with me to do some wiring, maybe I should put my tractor on it and do some testing myself. I havent loaded my Max Tow that heavy yet

 

[Blade1668]

The 4.0L redlines before 5k. The 150hp peaks at ~4250 and starts to roll off from there. Not only do you not need to spin it up like the 3.6L, there's nothing gained by going much over 4k. Conversely the 3.6L doesn't even make peak torque until ~4200rpm and peak power is at ~6200rpm. Fundamentally didn't engines. Of course with the extra hp, I'd bet the 3.6L is still making more power at 4k than the 4.0L. If you drive then both the same way you'd be disappointed in one or the other. The 3.6L doesn't like being loaded much below 2500 rpm. The 4.0L will still pull at 1500 rpm. Driven to it's strong suits (wind it out), the 3.6L is a much better engine in my opinion. Drive it like a straight 6 or an old school v8 and it's massively disappointing.

Personal opinions are different between different people. I'm quite familiar with 4.0 engines I currently have 4 Jeeps with them to include 2 of the high output versions. The Renix of pre 91 are a okay post are definitely better. (The H.O. pushed up to 192 H.P. in 91-92) then a slight de-tuning and changes to make lighter weight on some later 4.0s. I definitely surprised some on autoban in Germany with my Comanche being able to stretch it out and passing on hills. Tip
Otherwise my first vehicle was 350 w 4 barrel carb and second 429 w 4 barrel carb. Then a 400 2 barrel carb definitely a gas hogs. Many years of V-8's and inline 6 engines. . . Over 3/4 million miles on them of my multiple Jeeps. So I have a bit of experience with them. Low end not spooled up to redline to get power is familiar to me and preferably. My 05 Wrangler has hardly been to 4000 rpm in it's 21 years. On the 3.6 the winding them up is possibly part of the failures of the cam shafts issue. As that's the only place where they develop the power. At least when more than a few have came apart, when I was getting one of the "free oil changes" from my dealership they had a few 3.6 engines in the service department on pallets to send back. One had decided to let loose throwing part out the top end, not out of a Jeep but one other vehicle that used 3.6. I've actually seen and driven a old Ford straight 6 that had a rod depart from piston and still running with "new inspection port" in side. I've also got many miles driving M35a2 2.5 with inline 6 multi fuel engines. They have likely why I have preference for inline 6 engines overall. Not speed but torque and low end grunt.

 

[Zachanadandy]

Personal opinions are different between different people. I'm quite familiar with 4.0 engines I currently have 4 Jeeps with them to include 2 of the high output versions. The Renix of pre 91 are a okay post are definitely better. (The H.O. pushed up to 192 H.P. in 91-92) then a slight de-tuning and changes to make lighter weight on some later 4.0s. I definitely surprised some on autoban in Germany with my Comanche being able to stretch it out and passing on hills. Tip
Otherwise my first vehicle was 350 w 4 barrel carb and second 429 w 4 barrel carb. Then a 400 2 barrel carb definitely a gas hogs. Many years of V-8's and inline 6 engines. . . Over 3/4 million miles on them of my multiple Jeeps. So I have a bit of experience with them. Low end not spooled up to redline to get power is familiar to me and preferably. My 05 Wrangler has hardly been to 4000 rpm in it's 21 years. On the 3.6 the winding them up is possibly part of the failures of the cam shafts issue. As that's the only place where they develop the power. At least when more than a few have came apart, when I was getting one of the "free oil changes" from my dealership they had a few 3.6 engines in the service department on pallets to send back. One had decided to let loose throwing part out the top end, not out of a Jeep but one other vehicle that used 3.6. I've actually seen and driven a old Ford straight 6 that had a rod depart from piston and still running with "new inspection port" in side. I've also got many miles driving M35a2 2.5 with inline 6 multi fuel engines. They have likely why I have preference for inline 6 engines overall. Not speed but torque and low end grunt.

I'd argue that people trying to drive the 3.6L like it's a straight 6 is harder on it than running it up to the rpms It was designed to run, but that's just my opinion. We are passed 150k total miles between the 3 modern Jeeps we've owned without issues and they regularly see 6k rpms. The power rolls off on the 4.0L above 4200 rpms so there's no reason to run out any higher than that. The 3.6L is just getting to peak torque at that point. The Comanche was decently quick for its day with 0-60 in the 9s, but that's slow by modern standards. I'll take the 7.5s of the gladiator on 37s even if it does have to spin 6k to do it. Thanks to the 4.7-1 1st gear I've never found a scenario where the 3.6L couldn't get into the power band in a hurry on or off road. Not even towing 8k pounds. Would I prefer a v8? Hell yes. Do I want underpowered and low revving? Nope. Even the v8 would see 6k on the regular. The ~150hp was the wheel dyno rating for every stock 4.0L I've seen. The ~240hp wheel of the 3.6L is substantial by comparison. If you prefer to idle around and never even push the 4.0L into is peak power, that just proves you don't need much over 100hp to be happy. That's simply unacceptable to me. I've owned several 4.0L Jeeps, several v8 Jeeps (old wagoneers and an '01 WJ), several 3.6L, and a 2.0t. The 2.8L gm v6 in my old XJ was by far the worst, followed by the 4.0Ls. Especially at altitude. Dogs. The waggy 360 was a dog at high elevations too. The 4.7L v8 in the wj was good, but the 3.6L paired with the 8 speed is still better. The 2.0t was surprising, especially pulling grades at high elevations. I'll pass on the old school boat anchors, but you do you.

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