So dont know what to do. (1984 xj6 stock 4.2)

the other day I was driving and the car felt funny.. should have figured something was wrong then but i kept going... needless to say not 2 hours later i hear something snap and smoke begins coming out of my hood. check levels in both engine and tranny and theyre both empty.. bone dry.. i get a tow home top up fluids and leave it on axle stands to make sure nothing leaks.
a few hours pass and everything seems ok so i put her down turn her over and not 2 seconds after i put it in reverse i hear and feel countless bangs,snaps and grinding... look under and fluids are spewing from the engine tranny and diff... i take the valve covers off and the cylinder heads and the internals are pretty much gone... i dont even want to look at the tranny or diff because i have a feeling it could be even worse... now the body and interior are 9/10, i cant scrap the car just because of this. so my questions are as follows, i have a rebuilt mopar slant6 turbo in my garage. how stong are the stock engine mounting points on the car? this engine produces 400 whp and i dont want it to drop randomly... as for the diff should i just get a new one or a whole rear axle? id like to replace the stock dual spring set up with koni coilovers for a less boaty ride. also id like to convert the car to standard, does the drivers footwell allow for this? i know the brake pedal is beefy so id get a smaller one but even so would it be alot of work putting this in?


additional info
-i do have a welder and know how to use it
-i have done 2 engine swaps before, both inline 4's for my friends hondas and acuras
-and i do have most of the tools needed for large jobs such as tranny and engine stands, and such

 

How in H did tranny and engine go dry? If so, I amazed that the thing fired up again and drove the tranny to the point of making awful noises. you wouldn't be kidding us to the end of an engine and trans change, would you. Hmmm!!!

What do you have for a transmission to go with that slant six?

Yes, these cars were once available with manual transmissions. so pedal boxes can be found. or, the auto pedal box can be adapted to add a clutch pedal that you fab or find a suitable one to adapt.

The front cross member is beefy and can handle any engine mounts that you fabricate. Not limited to, but including hot BBC's.

The rear IRS is more than capable of that kinda power. Some traction control would be needed. Again, can and has been done, in many a way.

As to stiffening the ride? it is hardly mushy as is? but, a sway bar would do that.

The rear is a true coil over suspension. As anything else, it can be modified.

Heck, even the derelict VW based dune buggy in my drive has added coil overs in addition to it's torsion bar suspension!! I gotta see if it's badly neglected four will turn over. Run is another thing!

My XJ is a wuzza six. Not 400 HP, but tons of torque and quite spritely on it's Cadillac LT1 transplant. ,

Carl

 

thanks for the reply Carl,
and i have no idea what happened... my dad had the car for 2 weeks and he said nothing was wrong, once i pull it ill get a better idea as to what went wrong.
but as to the tranny, i have 2 sitting in my garage, a 4 speed manual from a questionable past and a i have no idea what from a somethingerother 70's musclecar still trying to figure it out..

but i dont know if either of these will work, when i rebuilt the slant i found a 420something cam to replace the 225 and with some fab it works. the engine itself puts out around 510ish at the crank last time i had it in a car it did 402 wheel but the tranny was a ghetto mod and the diff was on its last leg. with a proper tranny and diff i think it would be closer to the mid 400's

 

If I were you, I'd consider a regular small block Chevy conversion, or if you have a little money to throw at it, a Chevy LS1 conversion. They are very well documented and there's a lot of support available if things don't go quite right.

The engine mount points on the subframe are plenty strong. They will easily take an engine that puts down the torque required to make 400 whp.

I've never seen Koni coilovers for the SIII XJ sedans. Koni does make shocks and struts which are supposed to be really good, but you may want to consider ordering a set of stiffer springs to go with them. I used aftermarket King lowering springs and KYB shocks. This took a lot of the float out of the ride, but there's still some there. I would have went with the Koni's but they were three times the cost, and I just didn't have the money at the time.

The differential question is tough - how do you know it's shot? It's a pretty stout unit. Usually age takes its tool in the form or worn seals and seized brakes, not so much wear.

 

thing is im not sure its shot im just afraid to look... ill start taking things apart in the coming weeks but i hope its as you say a seal or something simple.. i was looking into an ls1 or a small block but thing is i already threw about 5 grand into this engine (slant 6) and i like the sound and the reliability of it. not to mention the garrett gtx4202r turbo i bought new and the custom manifolds i had to make... id rather put this in and spend my time making it work rather than spend more money on another engine

 

Yeah - your going to need to make the call on the engine first. Sounds to me like you have. You just need to make it work. Its pretty amazing to me that this very european car can actually take on such a variety of powerplants. As you have seen in this forum alone - a well done conversion works in an older Jag. It only depends on your time, money, and focus to make it all come together. I have not done a conversion with my Series III. I am considering it - for the future. I was able to source a used engine from Dave B. I rebuilt my trans, and final drive, and I am working on putting it all back together now. The general path to follow I assume is with conversion kits that you can purchase. If you use the engine in the garage, with your own transmission - I am not sure you will need much of anything to covert it besides what you already know you will need. You can purchase a complete pedal box - complete with clutch pedal right now on E-bay. Engine mount, trans mount, driveshafts will need to be modified. You should have plenty of room. Personally, I would stick with a Jag final drive and just modify the spring/shock combo to your liking. And - that is not cheap by the way... They sell KONI adjustable shocks for the Jag for almost 200 each when I was looking - and you need (4) total. Either way, if you think you have to replace the final drive - I would call Dave B. I saw at least three of them in his back yard!

Dave Bogerman - Everyday XJ.Com

 

Sunchip, My friend has his whole car for sale if you want to put in a EFI V12 and freshly rebuilt TH400 still with warranty. It 's an 88' that has over 80,000 mi and runs and drives pretty good. It's not a beater, but has some scrapes, chips, interrior blemishes etc and I'd put it at around $3000 worth easily. He don't want to just park it because of the crappy fuels they selling us now. He feels it needs to be continiously driven, and I feel the same way. His headlight switch isn't working correctly too. Maybe this car is a little newer, and be a lot cheaper to bring up to 100% rather than yours is right now?