.... This wastes a lot of fuel and kills my economy, but then again, it's a 50 year old engine design, you should expect much.
its a balance between tourque and fuel economy. gotta find the middle ground somewhere.
It's definitely a balance thing. That 50 yr old technology was, on my TJ and in stock form, capable of 23-24mpg. TJD60's was getting 24-25mpg. For a 4.0L engine that's not bad at all considering some of the new vehicles get this mileage or even slightly better but in an under 2.0L package and a light unibody car. I don't buy this "outdated engine technology" mindset at all. The older TJs were more economical than the newer (2000+) TJs and Rubicons. And with a regular distributor. Go figure. I believe the 4.0L engine to be quite economical in its class and even better than some smaller class engines. People modify vehicles, make them heavier, harder to roll down the road and then blame "old technology". The new manufacturing "standards" also amuse me. Make the vehicle heavier, slower and then wonder why the economy suffers. So let's throw more electronic gizmos in the mix to fix this. Making it even heavier and more complicated and less efficient as soon as one of those componenets is in less than 100% shape. Shame.
Its not so much that its outdated tech milan, its that its old tech. But its old tried and true stuff that still works, which IMO, makes it far from outdated.
The 4.0 has seen very few changes over the past 50 years.
Yes there are some older 4.0's that get slightly better milage, but there are also some key differences in those motors.
Those same older 4.0's are not the ones making 195hp and 240lbs of torque.
Most importantly, they arent making these numbers at the same rpm the older version made similar numbers.
I have not driven many older 4.0's that my 03 wouldnt walk all over, in stock form, or how it is now. But the cost of the changed cam timming, additional torque and hp is milage of course.
The 4.0 is still 100lbs heavier then a cast iron small block v8. As much as 300lbs heavier then the new aluminum versions that are out there.
There is no variable valve timming available for 4 litres.
There are no stock 4 litres comming out with aluminum heads, aliminum blocks, or rollerized valve trains. Mustangs have been rollerized since 84 or earlier.
The things mentioned above are becomming standard in a lot of engines, meaning the current tech used on 4 litres is still very basic and old school.
With the exception of an upgraded head around 1993, and the removel of the distributer in 02, there has been little to no change technology wise in the 4 litre for 50 years. Unless you count the addition of more and more computerized ignition timming and cat converters to decrease emission new tech. Which I dont as those things are external add ons.
If you spec out a crane cam for a 4 litre, have a look at cranes listing.
"AMC 4 litre, 1965 - presesnt"
Not even a sb chevy can do that, since they changed a lot of the bearing journals and what not after 69.
Like the saying goes, you cant get blood from a stone.
Without drastic changes to the ignition timming, valve train and timming, internal component compositions, etc etc etc, the 4.0 will pretty much stay the way it is. Not great on fuel but durable, reliable, and a very healthy lowend torque motor.
thats my 2 cents anyways.
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