Or as I should've called it.....What the hell have I gotten myself into again...


So, since I bought a car that needed a motor (spun bearing) and it had 117K miles on it I decided to get a replacement rather than grind the crank and get new bearings due to the known possible nikasil issues and due to the fact that I have no clue what was done to it before and no idea how it ran before it died.

Inspired by AVOS' thread:

https://www.jaguarforums.com/forum/g...k-4-2-a-23763/

I started to dig through the forums and search for a 4.2 motor.

I got lucky and picked up a 4.2 gem with 70K miles on it for $1100 bucks shipped. Pretty much complete but after a cabin fire so valve-covers and electronics are toast.

Well, what complicates things is that I'm totally new to Jaguars and again I don't even know what to expect from the car once it's done. So I'll probably be asking someone local (chicagoland) for a ride in a stocker to make sure my swap went right once it's done.

So so far I took the majority of the top end off and started comparing things. I'll post a ton of pics soon as I'm trying to document...where everything goes...and I'll try to post some comments as I go and as I edit the thread.

Again thanks to AVOS for answering my questions and providing a rough outline as to what needs to be done and sharing his knowledge.

Also thanks to Count Iblis as he also provided a lot of good info.

Hopefully the guys will not be shy to chime in here and help me along,,,, as I will definitely need help

 

Adam:
As I am sure you have figured out by now, the XJR swap is much more straightforward than a NA in that you do not have to deal with the VVT system- including how it seals to the valve covers and ports to the oil pump. Be sure to remember that as you give advice to others. I, for one, am looking forward to see your documentation. I am waiting for an excuse to put a 4.2 in either of my early XJRs.

 

Very good point! I forgot to reiterate that this is a SC motor swap. I figured that since I said XJR people would know.

 

Just picking up on a point Ross made, the VVT and oil galleries can be totally removed and plugged without much trouble. If the parts are available, it's not much of a job. The other point was an excuse to upgrade to 4.2....it has many benefits the way you've lined the job up. I trust and hope you'll find the performance of a 12 year old, 1.8 ton English saloon very favorable, it's no Porsche TT, but it should stay with any 911 up to an S4......no idle joke.

 

OK, so this is how far I got yesterday.


The 4.0 Pile


The 4.2 pile seems much smaller and I think there is way less plumbing in the 4.2. It also came apart easier as the 4.0 has some sneaky bolts.

One thing that wasn't mentioned before that I noticed is that the engine mount brackets look different and have to be swapped.





This is a pic of the two superchargers side by side. The new is up top and the old on the bottom. The top one seems to have Teflon coated rotors.


Here's the back shot. Old on the left and new on the right. People say they are not interchangeable and I do see the differences, however I don't see how one couldn't make the new one work in the old setup as it only appears to need a shim where the rotor bearings are in the back.

I do however think that the older version may flow better as the opening seems more unrestricted.


(4.2 on the left and 4.0 on the right)
Another thing I noticed is that the elbow in the 4.2 has a smaller exit, just like the supercharger and also the radius of the elbow seems crimped. I'm positive that the 4.0 one flows better.



Here they are looking at them from the top.





The 4.2 heads seem like they have plenty of beef for the retaping operation.





One thing however is that the old 4.0
heads are nicely transitioned in the head from the intake/injector runner. However as yuou can see on this picture they have much smaller openings than the 4.2. The black piece is the gasket off the 4.2 over the 4.0 ports.





This shows the same gasket over the 4.0 runner.

Now I'm not sure if I should port these out to match the heads or not?


I'm also thinking about smoothing out the intake ports on the 4.2 heads, however I really don't want to take them off the engine. I asked AVOS and he said that it wouldn't be that big of a significant gain



Any Advice? Seems like there is a few more guys here familiar with the swaps.

I'm stuck at this point and now I'll be looking into drilling the heads and tapping them. Hopefully I'll get it done tomorrow.


Also, the 4.2 has totally different knock sensors than the 4.0. I was wondering if they have the same parameters however AVOS said he wouldn't risk it as the ECU might be calibrated for the differently. Does anyone know for sure?

 

Before you start on the intake manifolds, have you read my update on the fuel rail/injectors in the 1st post?
Quick Reference: Swap your 4.0 block with a 4.2


My take on porting is that 1st of all I think you need to understand what you are doing to know if what you are doing is going to make a positive difference (it could also go the negative way). Sending the heads of to have it done by someone that knows what to do and has the equipment, is an expensive operation, and here I said that the benefits are small compared to the costs.

The 4.2 supercharger is quieter in operation due to the helical gears, has stronger bearings for more longevity, and has a special abrasive coating on the lobes that will ensures less leakage, so will be slightly more efficient. This was one on the first mods I did many moons ago, and easiest is to just drill out 2/3 mm of the 4.0 intake elbow where the bearings of the supercharger stick out, and use the 4.2 gasket. So wouldn’t just rule out to use that one…
I do think their operation is the same of the newer knocksensors (so in principle you can use them, no DTC to be expected), but as said, I don't know if the repsonse from the 4.2 (also used in the AJ27 engines) knock sensors are the same as your old ones. As long as no one can confirm that it's the same, I think it is risky to use them, as their function is so important.

 

Hey Avos, thanks for chiming in. I'll look at the supercharger and maybe will decide to use it. Have you opened up the intake on it to march the old elbow?

As far as the injectors, the rails I got and one injector along with the harness and connectors were toast due to the fire so I'd have to buy a lot of parts to make it work. Also I'd have to use the new intercoolers if I wanted to use the newer injectors and runners as the bolt pattern looks different. I'll give it a second look thou.

As far as porting I'd just smooth out the edges on in the heads dividers and port batch the intake runners. I still haven't made up my mind on it yet. I do have the tools to do it.

With the the knock sensors I'll try to dig up test procedures for both models. That should give us an idea if they are the same.

 

Adam if you can do the matching of the ports go for it. I guess you know the adage though, can't put back what you take off....
There's been two schools of thought on polishing both induction and exhaust ports, combustion chamber and piston faces, creating less friction and cleaner gas flow. I think this works if tuning a carb engine where gas flow isn't forced.
The other is leaving a rough cast surface, this forms a boundary layer and improved air/fuel mixture pre-compression. Ideal in forced induction set-ups.
Opening the ports to match is good practice, but won't gain 30-40 extra horses a 2 litre cosworth rally engine on twin Weber carbs would gain because you've got a blower shoving the mixture in even if it doesn't like it!
The 4.2 knock sensors are the same as the AJ27, the ring type. I'd go with what Andre suggests and stick with the 26 versions for safety - unless you discover the rings' run similar voltages and outputs, you'd have to add the threaded post to the AJ 26 to carry the rings' - and they'd have to be located in the same spot as 27/33, for me too much to be concerned about.

 

I gotta dig up the parameters on the sensors and measure them up. The ring one's I can get for $27 and the stone age one's are $70....go figure...

 

Let the work begin on taping

 

I set the drill bit to be about 2mm longer than the bolt. In 5 spots out of 6 it goes through the head into the valley.

I torqued them to spec 22Nm and there is plenty of beef to hold it.

 

I know this is sort of ghetto engineering but I decided to do some "work" on the heads....
Gods of tuning will hate me for this

 

Other side done...


Cutout on the openings in the heads



Matching the cutout to the 4.2 runners



Tommorow's project: Matching the 4.0 runners to the 4.2 heads. Gotta stock up on some sanding rolls

 

looking good boss keep up the good work

 

I'm in Chicagoland and I've helped design the ports on these cylinder heads. I've never machined them myself, but have had the machine shop do it for me ( I HAVE machined BMW and Mopar heads myself). I would be happy to give you some advice if you want to meet up. The AJ27 heads are better for 4 litre and as designed for their application where as the AJ33 were a clusterfeck - you'll notice the ports are assymetric and the transition- as you said- is poor. This is becuase it was meant to have a flap that deactived a port to better part load burn- this was sold to us by a austrian consultancy. We were left with this system that didn't work, worse is that the flap was causing mechanical problems and we couldnt meet the target power of 300 bhp and 400. So at the last minute it was up to my dept to start hogging the ports out as a last ditch attempt to gain the power regardless of the effects on in cylinder charge motion.
The later heads are a good base for further modifying.I would use the AJ37 Aston ports (also optimised by me) as a template to port to. Be careful not to overport and reduce your port velocities- there are guidelines for this (I have a spread sheet). Porting does help even on a SC engine a bit, I cant quantify this now as my memory is fading- I'd have to dig out the simulation and test results

 

The knock sensors on the 4.2 are probably for either the 32 bit EMS system of perhaps even the torque based PAN PAG EmS system where as the AJ27 featured the 16 bit system. I dont know of the compatibility. I have a friend who does (and lives in Warwickshire) , but he pissed me off and I pissed him off and we no longer talk

 

Do you have any more info on the shape of the AJ37 ports? Templates, pics or dimensions?

I've removed the center divider and roughly smoothed it in. I didn't use a grinder as I didn't want to produce a fine dust and the bigger chunks I was able to vacuum out and stop from falling into ports. I figured that It can't hurt removing them even if it won't help much. I know resistance is what creates boost, but it's the airflow that gives you HP

Next thing I want to do is to open up the bottom of the ports on the runners to match the heads to further smooth out the transition.


Another thing I'd like to ask you about is the TB elbow. The AJ26 one appears to have a better radius than the AJ33 one. Which one flows better?

I'm not trying to squeeze every possible HP out of this car as I'm trying to build it into a fun daily driver on a budget and I'm also pressed for time but small things I'm willing to do along the way to make it a bit faster

 

They are basically a piezoelectric sensor that produces electricity when it vibrates. Just like a microphone. I will try to look up the part# that are on them and see if I can dig up a spec sheet.

 

I read what you posted about the AJ26 vs the AJ33 and it suprised me. I dont recall which flows better. It LOOKS like the older one does- perhaps the AJ33 was more package constrained. I DO seem to remember the later 5th gen M112 being an upgrade and a tad more efficienct than the earlier one.
I DO have rubber mouldings of the AJ37 ports and the AJ27 ones, but Ive moved so many times in the last few years I'm still trying to find them. I think theyre in the bottom of a box unfortunately, ill find them one of these days.
I would certainly knife edge the port splitter and smoothen the short side radius.

 

Good thread guys,

@Count, would the AM ports be good for replicating on a SC engine? Can you give it 10 minutes of your time to locate them????? the guy in Warks, he didn't sign off the crappy diff by any chance?!