1983 XJS v12 to Cummins build
 

Hey all. I made an account with the facebook button but didn't like my name being my username. So here i am again!

I recently bought a 1983 XJS for $250. It has minor rust issues and i can see grass through the rear seat floor, and the engine and trans are completely gone. But thats fine! Because i didnt want them anyway.

My goal is going to be long and hard to achieve. I'm trying to cram a 5.9 cummins into it along with a manual conversion not using OEM jaguar parts.

Anyway, here's some pictures to start. I'm still debating on which cummins i want (theres a 1st gen near me but i have a friend who can help me out getting a p pumped engine). Gotta aquire the trans and driveline parts too. Gonna keep the exterior mostly stock but i might throw a big ass wing on it for fun



Only progress so far -

-got AAA to tow it to my house lolol
-started removing ski slope and dash board
-removed washer and coolant bottle along with radiator/condenser/AC lines

Might be picking up the engine next paycheck.

Cumming 5.9? A deisel? Are you planning to tow things with it? Do what ever turns you on... but a LT1 / T56 conversion would be more fitting with the sporting nature of the chassis. Probably cheaper too and one day some else might even consider buying it.

Awesome! Is that still an I6 or already a V8 engine? We don't get Cummins engines in our vehicles here...

that Cummins 1st edition 5.9L reach Max RPM of 3200rpm ,govenor limited.

you will need TWO overdrive gears.

not be fun running full pedal at 65 MPH.

There are ways to change the redline in the cummins among with other mods. I plan on making ~350 rwhp and 700 lbft when im done.

Many people have done LS / LT1 swaps in these cars. I'm trying to be just a little different :)

Anyway, found myself an engine!

im excitedto get this

my guy is gonna trade me the engine and trans for 800$ and a scrap ford explorer :)

I am interested in how you approach the upgrade to your suspension. That Cummins weighs tons compared to the aluminum block of the 6 or 12. I will be watching!! just PLEASE no Peterbuilt exhaust on it coming thru the aft roof!

The engine is only 400 lbs heavier than the v12 that came factory. it shouldn't require too much extra work

So I'm completely ignorant regarding Cummins engines. It's a name I thought was associated with tractors, heavy trucks, and industrial purposes.

What are the performance characteristics like, and how much effort will it take to match the character of the XJS, or are you going for something totally different?

I'm genuinely curious regarding your reasoning for the powertrain, although I think we may have been masterfully trolled here, fellas :D

Pud is an improvement on your real name? LOL

As long as you document the project here thoroughly (tons of pics!) and avoid that damn spoiler and a leaper at the end, you'll make some friends here.

Good Luck!

I'm very skeptical this project will ever move under its own power. I see many red flags and I reckon a person with the experience and technical skill to pull this off would probably know better and focus their resources elsewhere.

As an ASE certified Master Truck Technician. I see a couple real problems, hood clearance, as the 5.9 is a lot taller then the V12. You are also going to encounter a definite problem with the front sump oil pan, as the front cradle/crossmember of the Jag is the total support for all the front suspension. If you cut the cradle up you will weaken it, and have to rebuild it. With a lot of attention paid as to the structural strength, as that Cummin's is damn heavy, about 1100 lbs, or as you stated 400 pounds more then the V12. You will have to watch your ground clearance as well. The Jag already sits fairly low, and when you redo your front cradle you will have to extend it downward to strengthen it??? and dropping 400 more pounds on the front end you may need some roller skates to get over pavement cracks LOL. It's a very ambitious project and I wish you luck. I was trying to remember if I had ever seen a 5.9 with a rear sump oil pan? That might be an option???
I'am also doing one a little unorthodox. I have an 89 XJS and I'am in the process of dropping a Ford 460 in it. The 460 weights the same as the V12 about 700 lbs. The Ford 460 also has a front sump oil pan, so I also have the issue of the front cradle/ crossmember. So I'm speaking from experience. Fortunately my 460 is no where near as tall as the 5.9. My next dilemma is the width with headers, and the steering shaft. Good Luck with your's.
89 Jacobra

I see a straight axel in your future. Maybe a gasser. Lol

my idea for a Diesel Jag is a completly different plan!

probably never happen tho, money and time!!

PUD, you are really on to something that should be a lot of fun! I remember when I was a kid, one of the magazines.. I think it was Popular Mechanics had an article on a guy that took a Triumph Spitfire, removed the block and put a Kabota 18HP tractor motor in. fairly straightforward swap with a little fabrication. Why? because he wanted to! He got killer mileage, a little slow though. I know.. we are not talking about 500-800 ftb/lbs torque.. your project is on a super-scale! Good luck and keep us posted!

Thanks for the positive imput guys.
Removed the stock front sway bar from the car today to make room for the oil pan from the 5.9.

I should be getting the engine tomorrow if all goes well!

Right now the jag has these ghetto ass chevy engine mounts in it from the last hillbilly that had it. They pulled their motor before they sold the shell to me but left the conversion mounts. I'm going to add some plating to the chevy mounts and move the mounting area of the cummins forward about 3 inches to put the oil sump between the front radiator support and subframe where it shouldn't have any issues. I removed the sway link to make room. I'm not going for a crazy lap timer if anyone hadn't guessed so im not too worried about the front bar missing. One of the contributing factors to the cummins' height is also that some motors have a pipe from the turbo to the intake that raises the engine height by almost 4 inches. I'm rotating the turbo and adding an intercooler to avoid that issue and gain some wiggle room. I had considered the rear sump idea but the power steering rack is on the back of the subframe and i did not want to risk damaging that in the process, and the front sump gives me more engine to firewall clearance.

More updates to come.

xjs has engine bay does not have a lot of vertical clearance, i would bet a 5.9 is going to have the valve covers sticking threw the hood. also a extra 400lbs is a lot. of weight to add on the nose of the car. also front sump the engine is going to be way far forward. i don't see this working at all,

So many downers here.
But my day was uplifting!


https://cimg6.ibsrv.net/gimg/www.jag...edf4de2e52.jpg

https://cimg7.ibsrv.net/gimg/www.jag...5415c77194.jpg

https://cimg8.ibsrv.net/gimg/www.jag...7939e22684.jpg


https://cimg0.ibsrv.net/gimg/www.jag...4b55d26221.jpg

https://cimg1.ibsrv.net/gimg/www.jag...233746e9b0.jpg

https://cimg2.ibsrv.net/gimg/www.jag...ddf93c007b.jpg

Major props to white shirt dude! he helped torch off the weird torque converter adapter and transmission adapter that was in the truck.

Also major props to my dad and my friend Jeff for their help in disconnecting it from the truck.

Engine needs some minor work, gonna do all the gaskets i can before i install it, wire wheel off as much rust as possible. spit shine it hopefully

This build is going to work damnit!

That'll slide right in to the XJS... with a little cutting those motor mounts tabs around the bell housing will sit nicely on the frame, just weld it...no mount required. See if you can find another one for the boot for 50/50 weight distribution and then it'll be 12 cylinder again.

i would try setting that engine in the engine bay before you bother repainting and refreshing it up. don't have to get it mounted but just dangle it in there on a hoist and get a good look at how things are going to mesh.

This made me howl :D Doesn't sound like what you're doing is much of an improvement! Kudos for having the testicular fortitude to attempt it though - keep the pics coming. This is going to be one legendary XJS.

@89 Jacobra - is there a website with engine and engine bay dimensions? I've been entertaining the idea of an XJS lump, but with another V12.