POLL: You MUST lump your XJS V12
 

1: 2003+ Mercedes V12 Twin Turbo
2: 2003+ BMW V12
3. Toyota Century V12
4. Other (explain your choice)

Title says it all. Hypothetical situation. You must LUMP (Less Upkeep More Power) your beloved Jaguar XJS V12. What do you choose, and why?

Me, I go Mercedes. Proven powertrain with insane amounts of power. Have you driven a CL600? If you get bored with that, a $1200 tune gives you stupid numbers. They are common as Hondas here, so no problem getting work done at an indie, and they FEEL right.

Thoughts? Am I missing something else?

Jaguar 3.0 V6 diesel from the current XF (UK market). 520 ft-lbs at 1600 rpm, and 300 hp has all the refinement and power you expect from a Jaguar and most people would never know it's a diesel, it behaves like a gas engine.

I have driven one in the UK and averaged 47 mpg in mixed driving, on instant fuel economy on the motorway on cruise at 70 mph I was bouncing between 85-95 mpg. It just sipped fuel!

Best of all, it's still a Jaguar engine.

I would actually go the wankel route. Rather easy to get it in. Use a 3 rotor (or 4) Eunos Cosmo engine. TwIn or triple turbos and that would all fit in the engine bay. Power figures would be around 4 digits...

It's actually still a PSA 204 HDI FAP with some tuning by Jaguar...

Interesting choice - would have to be dirt cheap to make me consider it over a Benz with the requisite # of cylinders though - are they?

Daim, how's that power delivery? Been in two rotaries - 1 was a friend's mom's from the 70s or EARLY 80s when we were in junior high school LOL - and the other was an RX8. Both really peaky.

Not suitable for an XJS I would say, being a relatively heavy car. Not sure how turbocharging affects that. I can imagine, but haven't felt one. Bet it doesn't feel better than a V12 in this chassis though.

Happy to be shown different.

A normally aspirated wankel lacks torque so it needs the guts reved out of it. Add a turbo or two and you get that missing torque and actually get a lot more than you need. They can easily achieve more power with less worries... Hence why they were banned from Formula 1 racing!

I've driven a couple... A 2007 RX-8 and a 1987 RX-7 Turbo. The RX-8 ran smoother but the RX-7 was a lot faster than the V12 in the XJ-S.

The Turbo had a VERY smooth but steap torque curved which would reach a platteau really early and hold it for a long time. Kind of like the situation, where Jaguar V12 produces 90% of it's torque from idle up...

I also was allowed to start an Eunos Cosmo... The only 3 rotor wankel made as a production engine. Basically it is a 9 cylinder but runs as smoother as a V12 (proper V16!). This was awesome!

As the wankel is a rather easy engine to work with, you can basically, with some workshop tools, extend the engines. Some people have home built some 4 rotor wankel and currently a bloke is build ing a car around a 7 rotor wankel. Without turbos and with a displacement of somewhere around 4.5l (equivilent) it has the engine tester power output of like 1200 hp... Without turbos.

AJ16 supercharged 6 cylinder engine from an X300.
or
Aston Martin V12. One must stay English, at the very least!

I had completely forgotten about Aston Martin - I bet there are a few rotting somewhere just begging for a new life...

It was jointly developed by Jaguar and PSA. Shall we say offered as a factory engine by Jaguar?

No idea of price. Neither the diesel or the MB V12 are a realistic choice simply due to the integrated nature of the engine and transmission management in modern cars. It's simply not possible to separate out the engine management without the rest of the cars systems being present.

Custom ECU's are a possibility, but they never match the OEM drivability, power and emissions and it's a tremendous amount of work to try and recreate the fuelling and spark curves, not to mention variable valve timing management and turbos/supercharging.

That sounds better :)

Doesn't mean it is a bad engine... ;)

Exactly the reason why I would do a Wankel... No VVT to worry about, standalone ECUs help the engine perform as it should and ignition can be achieved via a normal dizzy or a simple aftermarket coil setup...

It was actually developed by Ford and PSA and manufactured by Ford.

https://en.wikipedia.org/wiki/Ford_A...D.2FTDV6.2FHDi

Convert it to front-wheel drive and put a Prius motor in there. *duck* *hide* :icon_duck:

When looking for a project/classic car, I only considered three options: Mercedes and Datsun. I mean that's before I found my neglected kitty...

I chose the Ford 460 for the shear simplicity of it. Simple electronic ignition, two simple 500 cfm Ford 2 barrels and with an overdrive trans, I should have low to mid 20's for mileage. Gobbs of Hp, and torque, and turn key driveability. No hassles, no overheating, Ac, and all the creature comforts wrapped up in a beautiful XJS. What could be better???

:icon_munching:i aint gonna touch this one!!!!

but here goes, Flint knows my choice for conversion, BUT it would be expensive!!. and WAY over the top for performance and better fuel MPG.

but from a practical money point plus good MPG, the Ford /PSA is an excellent choice.

i all ready know what transmission would be priced well, made in USA.

you would use the Ford factory ECU, to run the engine, and there are many trans. TCUs to use ,USA.

rotary just be many headaches, been there done them , at least 6 of rotaries.

rotary great for light weight vehicle, in a heavy car ,noway do it, fuel MPG would reqiure two pockets of money,, HE-HE.

Question wasn't regarding fuel economy Ron ;) The Jaguar V12 is no miracle on the dinosaur juice either ;)

I didn't know about the Ford involvement. Makes sense for them to make it though.