Swap 4.0 Litre from '91 Cherokee to '04 TJ Rubicon?

[Tinkerer]

I wondered whether the blocks would be the same so that I could take the '91, part it, keep the motor and make it a stroker, then swap it into the TJ, then do the same to the existing motor to have a spare or sell the stroker.  I'm looking at adding forced induction to the unit as well down the line.  I just want to have enough jam to daily drive this on hills etc. without barely keeping 80KPH full throttle in a 110 zone (Edit: My fan clutch was locked up, I have more jam now with my electric, but it still could use some assistance. P285 75R16 == 33" tires and factory gearing etc.)

Is buiilding one cheaper than buying one pre-built or ??   Some of them probably want a core I would guess.

[BlackYJ]

I just want to have enough jam to daily drive this on hills etc. without barely keeping 80KPH full throttle in a 110 zone

Are you still running the stock gears?  You have 32s right?  That does not seem right.  I have 4.10s with 33s in my YJ and I usually can hold 95-100 on decent hills on the highway

[The Machinist]

I went with a cold air intake, bored out throttle body, throttle body spacer and a stage one jet chip, made a noticeable differance.  I run 373 gears on 33's, my cherokee used to get hot on big hills and wouldn't go in to overdrive on the highway.   This combination worked pretty good, no more heating issues on hills and I can usually coast down the highway unless there is a strong head wind.  Going to put on a cat back soon to finish it off, this may be a cheaper alternative.  Strokers are expensive, cheaper to change you're gears in your axles and less wear on the drive train.

[Bnine]

You wont like that swap Pat. It is "possible" but a lot of fabrication, short cutting, and jerry rigging are required.

My stroker was a 98 block, 95 head, all running a 03 serp system, intake, exhaust and ignition.

Most of the issues.

Coil packs. No hold down boses. I used plumbers all around from valve cover to block bolts.

Idler pulley. No boss in older heads. Drilled and tapped for that.

Water pump. Different bolt patterns, and different pulley mounts. I have an 03 pulley mount, pressed on to a 98 waterpump to maintain the 03 serp system.

Alternator. Block is missing 2 bosses for the alternator bracket. I fabricated a mount that makes up for one, and deleted the other. My alt bracket uses 3 instead of 4 bolts.


So, can you do it, yep. But I wouldnt recommend it.

I've since gone to a hesco head just to address a few of those issues.

Hope that helps.

[The Machinist]

IMO, more torque/hp = more wear on your drivetrain.  If you have that extra power to push you up those hills and down the highway you are getting more wear/km because it is putting more stress on your drive train.  Another thought is if you put bigger tires on but do not change your gears in your axles you will rarely use your overdrive in your automatic transmission, which will put a lot more wear on the engine and tranny. 

[Bnine]

That goes either way, but most commonly underpowered will wear things faster. Unless you are abusive with the new found power.

Underpowered results in overworking the motor due to frequent down shifting, additional shock loading on the drivetrain, and increased heat in the transmission due to gear hunting.

Jeeps are famous for being slightly under powered from factory due to their weight, and shape. A few modifications for offroading and an increase in tire sizes results in a severly under powered rig. The 2.5 litres being the worst of the bunch.

[Bnine]

Golen has late model engines Pat, but to be honest, you can do the same thing they are doing with a simply cam swap.

Swap to a low rpm super torqy cam will dramatically increase that low end grunt, and add some power up top.

The biggest failing with late model jeeps and making power is the restrictive heads, and more importantly, the cam profiles that are designed to choke exhaust, therefore run the head hot, which in turn reduces emissions.

Opening those things up will make a very dramatic difference in your late model 4.0

To put that cam in your jeep it also requires a valve spring swap, and an old style cam retaining bolt and pin. All available through hesco if you are interested.

Oh, and if you really want to open it up, the aluminum head from hesco will make a significant difference as well.

I have done a lot through hesco in the last couple years. They treat me really good there. If you ever need anything, let me know. I can probably save you a few $$$.

[BlackYJ]

What I was referring to was that for the same engine/trans/tcase etc. and only a gear change to get back the "power", your engine/trans/tcase have to spin that much higher rpm for each KPH and that many more times per 100KM, so I'd expect more wear.  On the other hand, they don't have to produce as much torque at the output yokes/driveshafts to put the same torque to the axle shafts. 

The amount of extra revolutions I would think would be a non-issue unless you put in 5.13s with your tires, as long as you keep the jeep properly serviced.   Don't be afraid of a little higher rpms especially if it puts you in a more efficient range for the engine.  My old 4 banger loved to cruise on that highway at about 2500-2700 rpm.

[Rubi03 jef]

i am having the same problem . mine feels like im driving a 2.5 any little incline forces me to downshift to 4th

on the flat its good . but im barely making 300km per tank
can this be exaust or cat  filled with S#!T    

i want to be able to drive 100km and get 400- 450 a tank  any thing i can do

intake
exaust
cam
chip

please help

[Bnine]

A plugged cat (which is common) will pull power out of the jeep, but it will also most typically restrict your RPM.

Jeff, the next time you are over we can go through some engine tech if you are looking for a few more ponies.

[Rubi03 jef]

A plugged cat (which is common) will pull power out of the jeep, but it will also most typically restrict your RPM.

Jeff, the next time you are over we can go through some engine tech if you are looking for a few more ponies.

sounds good bnine    that would be appreciated .

[Rubi03 jef]

I thought something was wrong with mine!   Sounds like we both need to do some digging. This tank if I went down into the red would have been 500KM plus, but I still think this thing can do better... for 4.0 litres of displacement, it seems a bit restricted.   The biggest thing was learning to drive for economy, which the ScanGaugeII helped with a LOT.  It is said in various industries "If you don't measure it, you can't control it" and the overall "average economy" gauge doesn't measure with enough frequency to do anywhere near as much good.

I was thinking along those lines too.... wondering if getting stuck in mudholes etc. , despite the engine running, pushing exhaust out whether it bunged up the muffler or worse, got as far as the cats!

how are you getting almost 500km a tank .. i would be soooooo happy if i were getting over 400 . tips on your new driving