what are some of the difficulties if any if you what to put a 4.2 in a 5.0 car or viceversa----------thanks

 

Almost too many to count. The Engine ECUs of modern cars are too interconnected with the rest of modules in the car and they're all dependent on eachother - it's not like in the 1990s when you just needed to provide the ECU with power and the engine would run.

If we accept the above, and also the fact that a 4.2 engine won't run with a 5.0 ECU or vice versa, then the idea of running a 5.0 in a 4.2 car or vice versa would require so much work (complete removal of most if not all of the wiring loom and modules of the donor vehicle - and it still might have issues with new wiring in the car) it's basically a non-starter.

If you have a 4.2 and you want a 5.0 engine, sell the car and buy one with a 5.0 already in it. It will be cheaper overall, guaranteed.

If you have a 5.0 and are wondering about replacing a failed engine with a cheaper 4.2 engine - don't.

 

Theyre not even close other than the number of cylinders

 

You will most probably have to invest in an aftermarket, custom, programable ECU unit... whatever way you might go. Properly expensive stuff...

This is very common in the "custom market"... Do-able, but you better have the money for it.

Also you need to modify the body... Add new mounting points for engine and transmission...

 

its not that hard,as someone said. Replace engine, gearbox, mostly all engine and most normal and ring optical wiring together with variuos ECU(instrument cluster, security ecus, climate, suspension, GSM, infotainment modules, 3 bsi-fuseboxes etc) propshaft coul be needed to replace depending on VIN. the good news that current wires are still ok in some cases and just need repin then with diferent plugs, so no need to lay new wires from zero. seats should be replaced as they have diferent logic and control. 4.2 is very durable engine and really worth to replace those direct injecton engines , just abit of labour,patience. of course SDD and both facelift and prefacelift schematics is needed. I would say job for 2-3 weeks depending on speed you are used to work. good luck.

 

 

Anyone asking this sort of question in this way is almost certain not to have the skills needed and also to have very little idea of the vast cost if paying an expert tech to do it.

Just buy the car you want with the engine already in it.

 

You get a lot more stupid questions on this XF forum than just about any other forum I have been on.

 

Then you should be very thankful that your experience with forums is limited enough that this is the bottom of your barrel. Go spend some time on some JDM forums and then report back

Also, it's pretty unfair to class the original question as "stupid". He wanted to know what the difficulties were in swapping engines, both of which were sold in the same car. Not like he asked how long he could safely run his car without coolant for, or something.

 

No kidding. At the point that the mk2 Toyota Supras had fully depreciated we had just started a forum in 2003 and were overrun with teenagers asking all sorts of unbelievable things, quite often after they had already done something stupid WITHOUT first posting a question. They pretty much destroyed most of the remaining cars by about 2010 and now thankfully, decent examples have appreciated out of the price range of the young wannabe drifters. The CS forum has quieted down now to just a handful of remaining long term owners, serious collectors and a few brave souls attempting restorations. The XF tho is now on the downward spiral so we're bound to start getting questions like this as prices plummet, particularly salvage values. By contrast, the most serious forum I've been on is the National Corvette Restorers Society (NCRS) but it costs an annual fee to join which keeps out all the riffraff except me.

 

 

thanks for all the responses .very interesting .have 1 more question .what are the difficulties in putting a supercharger from a 4.2 on a normally aspirated engine. thanks again in advance-----------------------ps here in Atlanta there is a man who put a Lincoln ls motor in a 2007 xk ..and it does run albeit with a lot of lights and warnings

 

again no problem . just change inlet air section, injectors and dual pressure fuel pump from 4.2sc engine ecu need to be reprogrammed (throthle coul be recalibrated or changed to 4.2sc- they cost pennies on ebay) other way is use 4.2SC ecu but it will be tricky to "inject" in 4.2 NA electronic system as part of the car data is on engine ecu and central /rear junction box(conflict)

trickiest part is that aditional thicker head gasket is needed to reduce compression,otherwise engine will detonate on anything above 3000rpm. unless you use special fuel. fiting LPG as fuel also will help. not sure how much it will prevent on detanton- depends on LPG mixture(varies in countiries)

pistons are slight diferent on 4.2sc but i believe original pistons will work fine. basicaly plug'n'play. if you will push car harder after mod I recomend isntal 4.2sc torque converter which is diferent (uprated) to handle more nM and more HP diferential propshafts are perfectly fine. good luck. let us know progres and update with photos. let me know if you have aditional questions.

 

forgot charger cooling aditional radiator, pump and 10-12 hoses is needed. if you use old 4.2NA just plug pump to any live ignition on and put 20A fuse. 4.2s works this ways also it daoes not varies with engine load ,simply on all time..

 

@mark campbell ...

Anything is possible. Question is what is your end result? A car that drives on the road or some sort of a track car?
The swap of the engine or engine components is relatively easy. The most complicated part is making sure the engine and transmission sits properly in the engine bay and is not out of balance. You need brackets to make the new engine fits in the "new" bay.
However...

If this is for a street car, the problem is making all the computer bits work together and not have a Christmas tree lit on your dashboard at all times.
That will be the huge cost... to the point where it makes so much more sense to get the body with the engine that you want already in it!

If this is for a track car... then who cares?
Do the swap, make engine and transmission work and Bob's your uncle as they say it. The only complicated part is to make engine and transmission work together. You can find pretty decent aftermarket options to piggy back on the ECU to get it going. The Christmas lights will just make the car more race like anyway .

 

thanks again for the advise--the sc info is for my friend in mi.--he'll be happy bought the answer from here

 

>thanks again for the advise--the sc info is for my friend in mi.--he'll be happy bought the answer from here
Ya, after owning three Jaguars and being active on this list since ~2009 I think the only successful modern inter-Jaguar engine swaps I've heard about were between X-Types, S-Types, and the old Lincoln LS (which really was a Jaguar under the skin...) and only for the Ford Duratec 3.0 V6.
Everything else seems far too specialized.
================================================== =
You dreamed of a big star -
He played a mean guitar -
He loved to drive his Jaguar...

So welcome to the machine

 

just put a 6.0ls engine and a 4l80e like everyone else does and be done $1000 complete with harness and ecu.
I think most of this is all sarcasm. mine certainly is and the electronics and all the modules get a ton of info from the engine control module. and it controls fan speed, ac and hundreds of other functions. If the idea is to not spend so much money because the engine needs to be replaced, a 4.2 is a totally different engine and like I said before only really shares the same number of cylinders. The 5.0 NA puts out close to what the SC 4.2 did. big strides in development to get hp numbers seen by a sc earlier engine. And the 5.0SC, I have seen several taken to 700hp

 

4.2's liter engines came in 3 compressions 7,8 and 9.0 to1, a thicker head gasket that can drop enough compression to let you go from NA to a SC AND stop detonation is something I'd like to see work? since that's usually done WITH A DISH OR DOME in the PISTONS!