Why did the 4.0 inline 6 go away?
- Thread starter Midwest
- Start date
My understanding and I could be wrong was that they couldn't get it to meet EPA regulations any longer. But again I could be mistaken on that.
To heavy, to hard on gas and to reliable. I think they were feeling some pressure from government mandated MPG standards across there whole product line.
JeepinJaye
Member
I wonder that all the time. It's the reason I didn't buy one of the newer ones. I took my 92 XJ with the 4.0 to 408,000km (about 253,000 miles) without issue. It actually still runs, and the only reason I upgraded was to get my dream vehicle. My 04 TJ also has the 4.0L I6 in it.
Likely due to the Energy Independence and Security Act of 2007. Not absolutely sure, just a guess
Tighter emissions, crash regulations, and the cost of a production line producing an engine that only one model used anymore killed off the 4.0L.
I couldn't wait to post . I have a place in my heart for these engines.
The 4.0 , previously the 4.2 and then the 258 before , was a great engine in it's era.
Unfortunately , that era ended about 1983.
In the carbereuted era , it stood head and shoulders above most engines because of it's durability . In the land of the blind , the one eyed man is King.
The 4.0 is heavy , lazy , produces terrible numbers for its displacement , and sucks gas . On the positive side , it does all that for nearly forever .
As it continued to last and last , both 4 cylinder and v6 technology made strides and could easily out perform it . When the dust settled , the 4.0 inline 6 outlived its own necessity.
At the same time , it is a very
hard to stall, smooth , manageable engine that does little wrong off road .....and survives fine on the road when the drive train is geared correctly .
My question is not why did it not stay in production ...but really , why wasn't it updated , lightened , turbo/supercharged and developed into a lighter and more powerful engine with the same inherent reliability . The Cummins Diesel was, and many others .
To me , that is the sad ending of the "great little engine that not only could" but also did . Those engines have been a lot of places , and made a lot of smiles....and still do.
The 4.0 , previously the 4.2 and then the 258 before , was a great engine in it's era.
Unfortunately , that era ended about 1983.
In the carbereuted era , it stood head and shoulders above most engines because of it's durability . In the land of the blind , the one eyed man is King.
The 4.0 is heavy , lazy , produces terrible numbers for its displacement , and sucks gas . On the positive side , it does all that for nearly forever .
As it continued to last and last , both 4 cylinder and v6 technology made strides and could easily out perform it . When the dust settled , the 4.0 inline 6 outlived its own necessity.
At the same time , it is a very
hard to stall, smooth , manageable engine that does little wrong off road .....and survives fine on the road when the drive train is geared correctly .
My question is not why did it not stay in production ...but really , why wasn't it updated , lightened , turbo/supercharged and developed into a lighter and more powerful engine with the same inherent reliability . The Cummins Diesel was, and many others .
To me , that is the sad ending of the "great little engine that not only could" but also did . Those engines have been a lot of places , and made a lot of smiles....and still do.
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Same here and hope to see it ...FCA needs to increase displacement if they want some fast market share ..owners are screaming for it .
The inline 6 configuration in the Chevy Trailblazer s would have been about what the 4.0 should have evolved to . +-293 hp.
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Couldn't meet EPA regulations. Not to mention it's been around since 1965, so it was long overdue for something new. Most engines don't last more than 10 years before a clean sheet design.
The longevity of the power plant really speaks volumes...it and the iron Duke probably stayed in production about as long as any gas burning American engine ever has.
The real irony about the Jeep story is just the fact that these vehicles survived in the marketplace and they were always one or two decades behind the technology curve... even the 4.0 into TJ that we all love is not near as advanced as engines designed 1990 and beyond .
The engine had been updated and fuel injected, but really and truly it never produced dramatically better numbers.
Luckily the good things about the engine weren't lost along the way either.
It's it's truly an odd animal.. in one sense I'm proud to own it because I know it's going to be there and in another sense it frustrates me because I know it's not what could be in vehicle .
I want to cite that going off-road increases the leaning toward a more durable power plant but really when you look at everything made in the last 20+ years... Engine durability has greatly increased.
I remember when an engine was junk at a hundred thousand miles and that was the era that the inline-6 really shined.
The real irony about the Jeep story is just the fact that these vehicles survived in the marketplace and they were always one or two decades behind the technology curve... even the 4.0 into TJ that we all love is not near as advanced as engines designed 1990 and beyond .
The engine had been updated and fuel injected, but really and truly it never produced dramatically better numbers.
Luckily the good things about the engine weren't lost along the way either.
It's it's truly an odd animal.. in one sense I'm proud to own it because I know it's going to be there and in another sense it frustrates me because I know it's not what could be in vehicle .
I want to cite that going off-road increases the leaning toward a more durable power plant but really when you look at everything made in the last 20+ years... Engine durability has greatly increased.
I remember when an engine was junk at a hundred thousand miles and that was the era that the inline-6 really shined.
Americans want high rev hp over low rpm torque because they stomp on it at stop lights and when merging or driving on interstates. Off road driving isn't a concern. Our 63' Chevy pickup had an inline 6 that went on and on and on. My grandpa would load the back full of calves from the sale barn using the cattle racks in the bed and it coupled with a lower geared 4 speed, pulled the loads just fine. Back in the late 90s when these Jeeps were made you needed a bigger V8 to exceed torque numbers in the useful ranges. Making fuel mileage go to crap(ier).
Jeep should have replace the 4.0L with an updated inline turbo charged 4 cylinder diesel and had a larger 6 cylinder diesel option.
The Vortec V-6 in that era had similar HP and Torque specs to the inline 4L, but I bet if you overlay the curves the torque curve on the I6 is higher torque at lower RPMs and flatter through the whole range. And the engines outlasted the 2000 era V6s. I noticed the torque vs hp difference coming from my 2008 Highlander V6 to the 2006 Jeep I6. It's slower off the block but it twists the Jeep noticeably.
It's basically the same reason anyone would put an inline diesel engine swap versus a V8 in a Jeep. Which has the most use off roading after you change out all the gearing in the drive train? If I was racing a Jeep I'd pick something way different than if I was rock crawling a Jeep. Jeep more than likely switched motors simply because they were purchased by another company that had motors they used in other cars.
Jeep should have replace the 4.0L with an updated inline turbo charged 4 cylinder diesel and had a larger 6 cylinder diesel option.
The Vortec V-6 in that era had similar HP and Torque specs to the inline 4L, but I bet if you overlay the curves the torque curve on the I6 is higher torque at lower RPMs and flatter through the whole range. And the engines outlasted the 2000 era V6s. I noticed the torque vs hp difference coming from my 2008 Highlander V6 to the 2006 Jeep I6. It's slower off the block but it twists the Jeep noticeably.
It's basically the same reason anyone would put an inline diesel engine swap versus a V8 in a Jeep. Which has the most use off roading after you change out all the gearing in the drive train? If I was racing a Jeep I'd pick something way different than if I was rock crawling a Jeep. Jeep more than likely switched motors simply because they were purchased by another company that had motors they used in other cars.
My thinking is the engine ultimately failed to meet compliance standards because it wasn't ever changed enough in order to meet those standards....
And I realize I'm probably talking over my head... But ultimately anything that isn't changed is going to fail to meet emission standards somewhere along the road unless it's an electric motor.
I think one thing that may hold true if you look at the automotive industry in general an inline 6 has been out of favor for a long time and that the people that look ahead of these things did not see any value in updating the power plant .. which can involve the cost of re design , testing , retooling and so much more .
It seems as if it ended up as something that works and no one just wanted to fool with changing it and they let it live out as long as it could.
at the same time I guarantee you they didn't plan ahead too good or they wouldn't have put the 3.8 in the JK Wrangler...how in the world that vehicle took off like it did with that engine is a testimony to the markets desire for a roomier , more comfortable Jeep .
And the 3.8 v6 kind of goes down as another engine that wasn't really all that great... but would hold up ... drinking oil ...and I don't know how many worn-out little caravans I've seen ... And older pre 2012 JK's are everywhere that still run ....they're just tired .
And I realize I'm probably talking over my head... But ultimately anything that isn't changed is going to fail to meet emission standards somewhere along the road unless it's an electric motor.
I think one thing that may hold true if you look at the automotive industry in general an inline 6 has been out of favor for a long time and that the people that look ahead of these things did not see any value in updating the power plant .. which can involve the cost of re design , testing , retooling and so much more .
It seems as if it ended up as something that works and no one just wanted to fool with changing it and they let it live out as long as it could.
at the same time I guarantee you they didn't plan ahead too good or they wouldn't have put the 3.8 in the JK Wrangler...how in the world that vehicle took off like it did with that engine is a testimony to the markets desire for a roomier , more comfortable Jeep .
And the 3.8 v6 kind of goes down as another engine that wasn't really all that great... but would hold up ... drinking oil ...and I don't know how many worn-out little caravans I've seen ... And older pre 2012 JK's are everywhere that still run ....they're just tired .
Imagine if Jeep would have done something like that 3L Chevy diesel. But instead would have basically merged the 2.5L and 4L engines into 2 different 3L engines that shared a common block and transmission. Then customers could pick from a 3L turbo charged diesel or a 3L supercharged gasoline engine. Jeep engineers would have had the initial choice of 4 or 6 cylinders to optimize the design around but pick one or the other and standardize the 2 lines on the same core engine block, frame, transmissions, gears, etc. to cut costs down.
Yeah, it was just an old design that could no longer be updated to meet current requirements (mpg, smog, NVH, etc.)
Actually the basic design dates back farther than '65: "Sometimes referred to as the 196 engine, this engine was originally designed by Nash and introduced in the 1941 Nash Ambassador 600 model."
https://en.wikipedia.org/wiki/AMC_straight-6_engine
It's really quite amazing that it lasted into 2006. Even the original SBC didn't have a lifespan that long.
See, there you go thinking! It's always baffled me that jeep offers a V8 in the Cherokee, a diesel in the Liberty,,, but the Wrangler gets no options at all? 2020 we will finally see a diesel option in the wrangler, but only in the Unlimited or Gladiator? Maybe they should hire you or me to go over there and pull their heads out of their asses for them? Shit, I'd do that for free!