Usually for Glorious Garbage, I’m highlighting some embarrassing and yet fascinating car, something that encompasses both the glory and the garbage of the automotive world. This is one of the most majestic classifications anything in the automotive world can hope for, and deciding what makes it in or not is a job I take very seriously. Somberly, even. This time, though, it’s not a whole car we’ll be talking about, just the heart of one. The engine. Specifically the Jaguar AJ126 V6 engine.
This engine has had some pretty flashy homes, from the Jaguar F-Type to the Jaguars XJ, XE, XF, and F-Pace and the Land Rover Discovery and some Range Rovers, like the Range Rover Sport HSE. These engines were almost always offered in cars that also could be had with the bigger 5-liter V8, and there’s a reason for that, and that reason is what makes the AJ126 V6 such an amazing Glorious Garbage candidate: it used the same block as the V8.
I don’t mean a cut-down block like so many other V6 engines that were derived from V8s, like the Chevy 90° V6 engine, derived from the Chevy V8 small block, but with the numbers three and six cylinders removed. As in removed removed, with the block physically reduced in size.
Jaguar, though, didn’t bother to actually remove the unneeded cylinders, and instead just got rid of the pistons inside them, blanked off the holes, modified the crankshaft, made smaller, 3-cylinder-per-side heads, and then probably knocked off early to the pub. The result was a V6 engine that, seemingly by magic, takes up exactly as much room as a V8!
Here, have a look:
And it’s heavy, too! But not just normal engine-heavy: needlessly heavy, thanks to that big-ass chunk of metal hanging off the back of the engine, doing precisely, as the British say, fuck-all.
Because the block is the same size as the V8, the crankshaft has to be the same length, meaning that on that last un-needed journal is a balancing weight instead. The crankshaft also has split pins so each connecting rod can be separated, letting the spark plug firing happen at 120° of rotation. Remember, this block was designed for a 90° V8, and not the ideal 60° that’s preferred for a V6, so, you know, they had to get clever.
The bore is reduced on the V6 to 84.5 mm from the V8’s 92.5 mm, giving a displacement of just about 3 liters, compared to the V8’s five. The V6, with its supercharger nestled in the generous valley of that 90° vee, makes a respectable 380 horsepower.
Now, what I love about this engine is that it seems to be a near-universal source of bafflement to people, who are genuinely conflicted about how to feel about it. I am quite late to this party, and by no means the only one to find these compromises confusing. Videos have been made about it!
At first glance, it just seems lazy. They just blanked off the end two cylinders? Why would they do that? What possible advantages would you get in the car? None, right? More dead weight, more space taken up for no reason, compromises made for how the engine actually runs – what’s the advantage here?
And then you start thinking about money, because this is a British carmaker, after all, and they have a long and beautiful history of pound-pinching, and you realize that a same-size block means the same engine mount points, and that means you don’t have to re-crash test the V6 version of the car, and then things start to make a lot more sense.
I’ve even driven a car with this engine before, and driven it pretty hard, on a track, back in 2014 when I attended the F-Type’s launch event. That event let me drive, back-to-back, the V8 and V6 versions of the car, and at the time I was unaware of the peculiarity of the V6, which, I should note, was so disguised under plastic engine covers you couldn’t see the oddly short heads or anything like that, and during those drives I found I preferred the handling of the V6, due to the less weight up front. Now I know there could have been even less weight there! But you know what? I bet it wasn’t that much extra weight, probably 50 pounds or so.
But, significantly, I didn’t really notice anything negative – I liked the V6! It’s not a bad engine by any means, at least not in the context that Jaguar used it. If you were, say, to use it in a car that had no V8 option, it would get significantly stupider, because all the reasons that make this engine make sense would disappear pretty quickly, leaving you with an engine that was heavier than it needed to be, more complicated than it needed to be, and used more materials than it needed to.
Part of me just loves the eh-fuck-it engineering that went into this engine; don’t need the extra two cylinders? Just board them up! It’s like putting drywall over a bathroom door because you haven’t cleaned it in two years and it’s just not worth bothering now. It’s both half-assed and yet also pretty clever, given the circumstances. In short, it’s glorious garbage, I think in the best possible sense of the phrase.
Why not keep going? Let’s blank out half of the cylinders for a 4-cylinder turbo model.
Using the same bore and stroke, you’d have a 2L 4-cylinder. At the same horsepower per liter as the 6-cyl, it would be a 254-hp power plant. Not bad!
I’ll take my check now, JLR. You’re welcome.
Back in 2002 Jaguar had a prototype X-type with a 3L super charger based on the AJ30. The output was ~340hp and came with a manual and OZ wheels painted in British racing green. It was also left hand drive.
I had the wonderful experience to have a drive in it after I put snow tires on it. It was in Canada in the middle of winter. Project was cancelled 2 days after I drove it.
There is something vaguely Soviet about this solution.
No, this is definitely British. Positive grounds, driving wrong side of the road, and a myriad of other oddities.
Says the only country still using inches.
About how many stone does the engine weigh?
I can work with inches, if I have to, but measuring weight in pounds is so weird.
There are two kind of countries.
Those that use metric, and those that forced former Nazis to put men on the Moon.
Learning new things today about Liberia and Myanmar
What size are the square drives on your ratchets and impacts? As far as I know metric versions do not exist. So everyone uses Imperial for something.
We use fractions of the metric inch.
If it works ok why not? I mean there’s a long history of companys taking bigger engines as a starting point for ones with a smaller cylinder count-though usually it feels more complete than this.
From my work experience, I can confidently say the diecasting tooling required to create engine blocks is eye-wateringly expensive, and the machines that run them these days are even more so.
If you can save a lot using shared tooling with different inserts to get different parts it’s a good idea to do so, but in this case it looks like an entirely new tool, as the back half of that block is reduced so much.
In that case, one could argue it’s lazy, but at the end of the day the V6 is not the performance option, so a few extra ounces of cast aluminum isn’t really the end of the world.
Also, its probably not as bad as it looks. If you cast anything with a huge thick section, it’ll slow down the rate at which you can produce stuff since it needs to be cooled in the tooling longer, and it will create porosity, resulting in more scrap.
I would bet a lot of money that if you looked up at that area from the perspective of the crank’s axis, you’d see they cored it out…. but not really to save weight, but to keep an even wall thickness so they don’t have issues in production.
Another thing to consider is the savings that cascades down the assembly line; factories only need to have ONE set of engine carts/assembly lines, because the engine mounts are the same, basically the entire assembly line doesn’t need to change at all in order to produce either engine, so they can adjust manufacturing of the V6 vs V8 vs real time demand to maximize profit.
There’s a lot of stuff to think about. End of the day, I am just happy jag is still around. For now.
I can understand the deleting cylinders without shortening the block, it’s a clever solution for a cash strapped company. What bothers me was the decision to delete cylinders instead of deleting the supercharger.
I’m sure the math was done on production and development costs. I still don’t like it.
If it works, is it really a dumb idea? I say no, especially in this case. It is a Jag. If you purchase a jag expecting efficient and well thought out design, then you are the dumb one. Jag’s have always been about the look.
I had no clue that this is how JLR did this…it somehow seems like a very British way to solve this problem. I don’t mean that in an offensive way, because I’m also on the fence regarding if this was a good idea or bad.
The timing chain design is still garbage, so, that bad design carries over haha.
“I Can’t Decide If This Jaguar V6 Made By Blanking Off Two Cylinders From A V8 Is Genius Or Just Lazy.”
It’s like buying a box “Hamburger Helper” and skipping the ground beef and serving your family just “Helper.”
(a riff on Randy Quaid’s line in National Lampoon’s Vacation)
I do kind of wonder if the extra space allows for counter balancers without the need for a separate shaft and chain system like the 4.3 GM v6’s needed in the end.
I suspect the main reasons for doing this were twofold… first… money. Doing it this way enables them to reuse a lot of the V8 parts and tooling… likely saving a ton of money. The 2nd reason for doing this is because with Ford divesting Jaguar and LR, they were losing/lost access to the Ford Duratech V6.
EDIT: And they also needed to develop a V6 as the V8, with the cost of fuel and CO2 emissions standards, made the V8 practically unsellable in places like the EU.
It’s the automotive equivalent of making a pair of cut-off jeans, but not cutting the pant legs all the way off, so you stick your legs through the holes, and leave the pant legs flapping behind you. Technically, they are shorts…
I don’t see anything wrong with doing this tbh.
This design solution offends me as an engineer.
On the one hand, ingenious use of materials at hand. On the other hand, you’re just asking for trouble later on because of all the changes you need to make.
One of the things I’ve always liked about this mill is the sound. In my experience V6s either sound amazing or terrible with very little in between. This one sounds incredible and in this day and age a supercharged 6 isn’t something to take for granted. Plus F Types depreciate like crazy and are, in fact, really great cars.
My aunt has one with the V6 and she absolutely loves it. In fact she’s planning on meeting me at a track day with it this summer. Right now you can get pretty decent F Types in the 30s and less than ideal examples in the 20s. It’s a ridiculous amount of car for that price if you can live without a manual, since they’re pretty rare.
But the auto is a ZF8 which is in contention for the best automatic gearbox of all time, so it’s not like you’re dealing with a slusher. I’ll also occasionally see the sedans and F Paces with this engine for tempting prices but I just don’t want to deal with JLR long term ownership in a daily.
Gee… why didn’t they just give you the V8… then deactivate the cylinders… kinda like those old school GM V8-6-4s… Couple that with world-renowned British Electronics, and you have yourselves a true winner (according to the repair shop’s accountant).
Eric tore one of these apart on his I Do Cars YouTube channel recently. His thought – and it seems like a pretty good one – was that this should mean that the V8 should drop right into the space, using all the same mounts. Figure out some electronics, and you’ve got a relatively easy swap if you’re so inclined.
Side note, I love that channel. Just taking random engines apart all the time, and his continual fight against dipstick tubes.
And the Used Water Pump Cinematic Universe which keeps getting bigger every episode. 😉
What is his deal with dipstick tubes? I recently had my own battle with one. I despise the design on subaru.
They often are extremely hard to remove and he struggles mightily for the camera.
I believe the parent company has an entire line of business dedicated to this kind of work:
https://www.tcs.com/what-we-do/services/consulting/white-paper/strategic-cost-cutting-for-better-margins-management
“. . .during those drives I found I preferred the handling of the V6, due to the less weight up front.”
Ha, if nothing else the cheap laziness of creating a V6 with a sub-optimal angle, and then not even removing the unnecessary cylinders, was a good placebo test for product reviewers.
Anyway, if one wants a proper 60-degree V6 without the weight of unnecessary cylinders left in one of the worst places for excess weight, forget a trash Jaguar, the Camaro is still available this year.
Actually Jaguar did use the V6 without a V8 option. The XE and second gen XF never got the V8 as an option only the V6. As I understand it the V8 heads would not fit as there was not enough clearance but the shorter v6 heads would.
For the crazy and wonderful XE Project 8 Jaguar modified the firewall to make the V8 fit, but this was not feasible for mass production which is why there was never a proper C63/M3 rivalling XE.
Honestly I never think about the engineering compromises in my F Type V6. It sounds great and goes well enough for me. Also the twin central exhaust setup on the V6 looks better than the four battleship gun exhausts on the V8.
Thank you for enriching the everyday automotive landscape with that beautiful car. The F-Type is one of my all-time favorite designs!
Sort of related: when Ford announced its Fox 1.0 turbo triple they were very keen to bang on about how tiny the engine was, and even said the block would fit on a sheet of A4 paper (which it didn’t).
However, as that engine was a replacement for their 1.6 four cylinder engine it had to fit in the same cars. The front case casting was enormous, stretching over the gap where the missing cylinder would have been, so it could reach across the engine bay to connect to the engine mount.
With the added cost of the turbo I suspect it wasn’t cheaper to build either.
It is appropriate that they bragged about how it would fit on a modest sheet of paper as that is the only place it looked good.
Turbo downsizing only makes sense if all your customers drive exactly like the WLTP test cycle.
As a designer of fine engines for the gentry, and also of cheap engines for shitboxes, I suspect the guys responsible for this do not have the drawings framed in their office, and don’t have one of the castings as a centrepiece in their home.
If it were famously reliable I guess they would eventually become proud of this engine, but…
Yeah, probably not something to showcase, but I am sure there were plenty of atta-boys going around internally.
I’m sure the project managers got really excited about the cost savings.
Then left just before it went into production so they could use it as a example of a successful project before the risk of running a disaster.
I’m pretty sure the very first car modification article I read as I was getting into them was in Mother Earth News, not Hot Rod. It described how one would go about turning a v8 into a 4-cylinder. Early 70s during the Gas Crisis. I don’t remember the details now (how do you keep the carb from feeding the 4 dead cylinders?), but I did look it up again in the 90s, so it’s not just my imagination.
Remove the lifters and everything up to the valves. No airflow, no carb feeding dead cylinders. As a bonus, you get an “air spring” in each dead cylinder to help lessen the drag of the cylinders going up and down.
This is basically what GM’s displacement on demand system does, but they collapse the lifters by not allowing oil into the lifters.
That makes sense as my memory of the article from the 90s includes that of a picture of a head being disassembled. Thanks.
They actually ADD oil to ports on the sides of the lifters depressing a pin allowing the lifter to collapse (same as the 5.7 Hemi)
The ghost of British Leyland casts a long shadow over its children.
Sometimes it casts a long cylinder block over it’s V6s
Too literal. You ruined it. Mine was much more poetic.
You’re a creative, I’m an engineer. Ruining something artistic is what we do.
I need that on a bumper sticker.
The calcs show the adhesive will fail, I’m going to have to rivet that on to your bumper.
I’d be more concerned about the open deck block and 4 bolt heads. That’s what all the disaster engines of history used – like the Chevy Vega and the GM Fuel Pincher diesel – that lead to blown head gaskets.
The main reason was that they needed a smaller engine than the AJ133. The old Ford Duratec V6 was past its prime and they couldn’t afford to develop a clean sheet V6 (this was back when all JLR employees were working 10% extra hours without being paid due to the recession – I know, I was there) so this was seen as a cheap & simple solution.
As a fun aside, JLR also did a research project called Ultraboost with was a highly boosted 4-cylinder engine. That used one bank of the AJ133 V8…
Did they use one bank to boost the other?
Nope – just got rid of it completely. The crankcase was a V8 but the top was blocked off so no block or anything.
As an ex-JLR employee myself, this sounds about right.
” The old Ford Duratec V6 was past its prime ”
There was nothing wrong with the Ford Duratec V6… except for the fact that they were probably losing access to the design and any updates to the design given that Ford sold off Jaguar. Plus, that engine was being built at a Ford engine plant… and that situation wasn’t going to continue indefinitely after the sale.
And it wasn’t powerful enough, and it wouldn’t meet the future emissions regs.