Jeep 4.0 I-6 in a BII?

[Jason]

I'm having trouble seeing that the Jeep 4.0 can be much different than a pushrod Ford 4.0. They have nearly the same bore/stroke. They have the same peak torque which means they are getting the same force out of the fuel. The Jeep lists it peak at 4,000 and the ford at 3,000 for the year I'm looking at. The Ford 4.0 makes 200ft# at 1,000rpm--no way that Jeep motor is going to do any better. The Jeep makes 30 more HP, but does it at a higher rpm--both show 125psi MEP at max power and 140psi at max torque. They appear to be the same engine--one in a row one in a V. I can't think of a bigger waste of time and effort.

I didn't look at the transmission ratios on the Jeep. Since everyone has a better first gear than a Ford, I wouldn't be suprised to find the perceived difference there.

Or a difference in the exhaust, intake, valve train or many of the other things that affect power output and fuel consumption. I never got more than 14 mpg out of a Jeep 4.0. I rarely get below 16 in my Ranger driving it the same way and having more weight to move around.

 

[Sevensecondsuv]

Sounds like as much work as a 300 straight six swap without the insane amount of off-idle torque of a 300. Not to mention a 300 will usually last 3x longer than any other engine under the same circumstances.

Don't get me wrong, I like the 4.0 I6. I've had several friends with them in jeeps. They pull pretty hard (most likely just the gears and 1000 lb advantage over my explorer). But they are thirsty suckers. Didn't seem to matter what vehicle they were in, YJ's, XJ's, ZJ's, WJ's - They all struggled to get 15 regardless of how nice you drove.

 

[Beanmachine7000]

Yeah, like I said my buddy's Jeep I drove felt like it had tons of torque, but I've never driven a 4.0 Ranger so I couldn't really say which way is best... And about the 300, My grandpa used to have a F-150 with that thing and it was a monster... He used to pull a cattle trailer full (6-8 head of cattle), that thing would out-pull anything short of a semi truck, lol... I'd like to drop one of those in my BII also. So many choices!! It all really depends on what I find, if I find a full Jeep drivetrain with a manual tranny, I'll probably do that, but if I can only find an engine I'll probably end up going with the Ford 4.0... who knows... I'm still looking for my engine, lol...

 

[Sevensecondsuv]

Well it's easier to put a 351 in than a 300, so don't get to thinking a 300 is good idea...

 

[Beanmachine7000]

Haha... Yeah I'm not even going to try that, and I think that the Jeep is out of the question too... It's looking like I'm going to have to finish this before the end of summer (I go away to school the end of August) and I think the Jeep will just be too much trouble... So, it's probably either going to be a 4.0 (if I can find one) or rebuild the old 2.9... So any one have any suggestions? I'm sure everyone is gonna be for swapping in the 4.0, but I'm kinda looking to save money now since I now have college to get ready for and moving out and all...