Jeep: give us a new power plant!

[Jonny A]

We ran down to San Diego on New Year's Day to see grandkids, my wife has a lead foot with the proper motivation. The Grapevine is lots of long pulls uphill, and 80-85 MPH pretty much the whole way. Traffic was MOVING that day, what little of it there was, we were constantly being passed by faster traffic. 6 hr trip in 4.5 hrs with a stop for lunch.

17.8 MPG calculated.

JTR 8spd with 35's and corrected speedo.

I get same if not slightly better mpg on my 35" JTR. I-95 up through Maine and the New Hampshire White Mountains. Pentastar operates as I hoped, no problems.

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[JoeDoc]

Sooo, I was driving around and caught a glimps of this Scrambler FOR SALE around the corner from my home in Chagrin Falls Ohio a couple years back. I couldn’t help but stop when I noticed the owner putting the sign in the window. If anyone can claim this truck I would love to talk to you again. Please send me a PM. 5.7 Vortec!
???

 

[JoeDoc]

I never could blow up the picture enough to be able to get the phone number off of the photo

 

[dcmdon]

Very cool.

 

[Firestarter]

uh, this says 150hp and 245 ft lbs. https://www.jeeptech.com/engine/amc304.html

You also have to note that engine power ratings are measured different now than then.

you are also comparing a far more capable machine. Even the entry level gladiator has a more capable drivetrain, so that’s 4,650 lbs not 5,050.

Also, the JT has a far better transmission which is able to keep the engine in a higher power producing rpm. The JT has way deeper gearing, so it doesn’t need a lot of torque to move its fat butt. Congrats if you have a stock CJ, but once they have armor, larger tires, better suspension, and actual people riding in it they become heavier.

https://www.jeepforum.com/forum/f8/how-much-does-your-cj-7-weigh-455976/#/topics/455976

as you can see, they are around 4K lbs on the trail vs a 5.5k lbs gladiator.

this also doesn’t take into account that a new engine will have a flatter torque curve from better ignition, fuel metering, and camshaft technology.

I still can't get over the fact that my 1978 CJ-7 had much better power to weight than the current Pentastar Gladiator, and that power came on so much earlier in the power band - where it is usable. The 3.5 NA V6 in the 3rd Gen Tacoma gets the same critique as the Pentastar, as do most other engines in the mid-size truck segment

2021 Gladiator with 3.6 NA V6 Pentastar: 285 hp at 6400 rpms, 260 lb/ft at 4400 rpms (Source: Jeep).
Curb weight for Rubicon: 5,050 pounds (Source: Jeep).

1978 CJ-7 with 4.2 NA I6: 200 hp at 4400 rpms, 280 lb/ft at 2200 rpms (Source: Wikipedia).
Curb weight: 2,770 pounds (Source: Automobile Catalogue).

Yeah, all the current mid-size truck engines have more hp than Jeep's 1978 I6, but that CJ-7 was a much lighter vehicle, so the power to weight was actually much better in the CJ:

2021 Gladiator Rubicon: 17.7 pounds of vehicle weight per horse power.
1978 CJ-7: 13.9 pounds of vehicle weight per horse power.

2021 Gladiator Rubicon: 19.4 pounds of vehicle weight per unit of torque.
1978 CJ-7: 9.9 pounds of vehicle weight per unit of torque.

In order to get the same power to weight ratio we had in 1978 in the CJ-7, Jeep needs to put an engine in the Gladiator Rubicon that makes 363 hp, and 510 lb/ft of torque!

Conclusion: We need a better power plant in the Gladiator, but one that is relatively affordable (let's say $3,000 over the price of the Pentastar).

 

[Challenger85]

I mean I wouldn’t be mad if Jeep put a 6.4 in there. The 5.7 is nice but the 6.4 is heaven.

 

[ShadowsPapa]

uh, this says 150hp and 245 ft lbs. https://www.jeeptech.com/engine/amc304.html

You also have to note that engine power ratings are measured different now than then.

you are also comparing a far more capable machine. Even the entry level gladiator has a more capable drivetrain, so that’s 4,650 lbs not 5,050.

Also, the JT has a far better transmission which is able to keep the engine in a higher power producing rpm. The JT has way deeper gearing, so it doesn’t need a lot of torque to move its fat butt.

He said the 4.2 which is the 258, not the 304. The 258 has better grunt or low RPM torque than a 304, IMO.

The JT transmission is nice but the programming does not keep the engine in the power-producing range. The opposite - it keeps shifting up and dropping RPM into the mid teens. I have to force it to stay in the mid-2,000 rpm area. I only WISH these stuck into the higher RPM and thus higher power band. Instead you have to romp it or shift manually to keep it there. Mine actually upshifts on hills, then has to downshift again after it fails to accelerate.

 

[ACAD_Cowboy]

The 258 from a giddy up go aspect was a wonderful jeep engine. My CJ came with the 151 and that was a living nightmare of screaming high rpm action to get anything done. When the 151/5 speed came out and the 258/T176 went in, the dana 300 and 4.10lsd my CJ7 suddenly felt weightless and effortless in terms of dynamic feel, the balance of power was right on.

 

[JoeDoc]

I mean I wouldn’t be mad if Jeep put a 6.4 in there. The 5.7 is nice but the 6.4 is heaven.

https://www.moparonlineparts.com/ca...performance-parts.html?part_name=crate engine

 

[Challenger85]

https://www.moparonlineparts.com/cat/2021-jeep-gladiator-mopar-performance-parts.html?part_name=crate engine

That is sweet. But you’d need a new tranny too wouldn’t you? The HP70 or 75? I think thats what my challenger had.

 

[Dryfly24]

So two complaints and that makes the diesel a bad option ? How many complain about how everything works and it does what it is supposed to do. You never hear from the ones who have no problems and love it. But then again I don’t troll around for stuff either

Actually I was just gonna post that as long as the engine/tranny combo is reliable, I am perfectly happy with what I have. There’s plenty of power to suit me. I prefer reliability to a big power house motor any day. I’m not planning on towing anything. I just want it to get me there and back every time.

 

[WXman]

LOL at this thread.

A JL or JT with ANY engine option available will dust a CJ like a coffee table. It's not even a contest. Not even close.

And, today's Jeep doesn't have a carb to fight with on cold mornings or when off-camber in the woods.

I miss the engines of the 1980s exactly zero.

 

[Dryfly24]

How in the world do you get 20mpg going up any type of grade? With 4.10s I could barely hold 8th gear here in Texas and above 75mph the fuel economy just dropped to 15. That was driving back from Roswell on relatively flat highway.

With 35s I've dropped down even further and I definitely do not have a lead foot. Typically I've always gotten better than advertised mpg but the Jeep is not having it. I get better fuel efficiency in my full size Navigator loaded up.

I live in Las Cruces. Drove it back from Rosenburg, TX last month and averaged right around 19 mpg on 35’s. Since I’ve had it I’ve averaged anywhere from 20 to 17 mpg depending on how hard I was flogging it and what I’m carrying. Getting ready to go on a multi state western trip at the end of the week. Fully expecting it to do better than that dog of a Tacoma I was driving before on 33’s.

 

[dcmdon]

LOL at this thread.

A JL or JT with ANY engine option available will dust a CJ like a coffee table. It's not even a contest. Not even close.

And, today's Jeep doesn't have a carb to fight with on cold mornings or when off-camber in the woods.

I miss the engines of the 1980s exactly zero.

You said it better than I could.

The 1984 Corvette made 205 hp.

Enough said.

It was a terrible era on another topic. The fashionable female dress was more covered up than any time since the 1940s. Remember the huge loose Beneton sweaters?

 

[ACAD_Cowboy]

LOL at this thread.

A JL or JT with ANY engine option available will dust a CJ like a coffee table. It's not even a contest. Not even close.

And, today's Jeep doesn't have a carb to fight with on cold mornings or when off-camber in the woods.

I miss the engines of the 1980s exactly zero.

Come on, you know you miss the smell of starting fluid at -10, the way that starter cable is just about to become transparent from the heat. Admit it, in some weird way you miss sticky secondaries that flood open after hanging up, making even the most mundane drive anywhere feel like outlaw drags.

The only reason my CJ had any scoot was it weighed very little, 2 seats, no top, missing a lot of body metal, heater was removed, no AC, no crash safety... engine was the heaviest part. It was loud, hot/cold, drafty and stank of gasoline and gear oil. No one ever wanted to ride in it and even the troopers stayed away, one told me one day he'd be afraid to look to close; run out of citation slips before running out of citations. We laughed!

You said it better than I could.

The 1984 Corvette made 205 hp.

Enough said.

It was a terrible era on another topic. The fashionable female dress was more covered up than any time since the 1940s. Remember the huge loose Beneton sweaters?

High waisted mom jeans, you remember the ones; buttoned just about to the collar.

The 90's were a rough time as well, body suits under skirts and tops, combat boots laced to the knee, all the bracelets and hair bands, all covered in a trench coat and the guys looked just like the gals making night interception missions iffy.

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