...someone mentions how great the 4.0 AMC/Jeep Powertech I6 engine is I think of this.

This is the Toyota 1FZ-FE, and let me say that I'm not saying that the 4.0 isn't a great engine (it is) but given its 4.0 liters of displacement and that it makes its peak torque (225 ft-lbs) at 3000 rpms, I look at this chart at see that same torque figure (225 ft-lbs) is available at...oh...idle. Not bad for an extra 500 cc of displacement. I should also say that im not diminishing the greatness of the AMC engine, only that I feel a little sad that this engine never gets remember in the annuls of automotive greatness along side the AMC...by virtue of sheer number built I suspect.


The 1fz-fe wasn't produced for many years because the vehicle it was meant for just got too big and heavy for an I6 so it went to a V8 just 5 short years after is was introduced (though it continued to be produced in other markets until 2005 and in forklifts in carburated and LPG forms to this day). It is generally regarded (aside from an issue with the head gasket) as the most durable gasoline engine ever built. Given that mine is on mile 240,000 and running like a top and many are doing 300,000+ without issues (or re-build) I'd say they may be right. It was designed to be rebuilt 3 times (with bore work, more without) and many people who tear them down, even at 300,000, to do the head gasket (an issue with 90's materials) find that the bottom end is in perfect condition, and not in need of work at all.

If you want to read more on the engineering and history of this amazing engine, there is a good writeup here


The only downside to this engine is that its saddled exclusively to an SUV with permanent 4wd that weighs, stock, more than 5000 lbs vs the XJ which got 2wd and weighed ~3200 lbs. The jeep has better performance to be sure, but most of that was the weight. I'm still blown away with the idea that at ~1200 rpm (where my torque converter starts really holding) I'm producing more torque than the amazing 4.0 powertech did at its peak.

You feel it when you are off-roading or carrying a load. I've discovered it really doesn't matter how much weight you put in the truck, it will get the same mileage and drive the same. I've loaded mine up with ~1500 lbs and still got the best mileage I can hope to get on the freeway, and couldn't tell (aside from braking) that I was even carrying extra weight.

Torque: its not how fast you can do it, its how much you can take with you.


Also - I know I'm totally overplaying the cruiser hand of mine. Don't care. Okay, I do, I will try and ease off.