DIY Improvement to Performance & Economy of AJ16 Engines

[davidr]

I knew it was too good to be true! Bloody thing didn't load the final image!

Thanks Paul and Vince for your offers of help but I've persevered and beaten it! The IT challenge that is - the bracket installation was quite straight-forward!!

[davidr]

So after all that what was the outcome?
Well it was too nice an afternoon not to drop the top and go out for a drive - after all, could be the last chance this year!!
I felt the difference straight away. It's not dramatic and it hasn't totally transformed my car but it has given it extra verve. Pootling along you don't feel much difference but maybe that's where the economy comes in - too early to tell yet.
When you put it in Sport mode and plant your foot then the kickdown comes in and there's definitely some extra pull. The engine feels stronger and pulls more eagerly.
I also fancied that there was a slightly harder edge to the exhaust note. It sounded a bit more like an E Type in that there was a bit of a rasp to it under full throttle.
So on the basis of a half hour blast around the lanes I'd say this was a success.

[Brakebuster]

cool

BB

[naki]

i think thats pretty much the gist of it. i have read loads of reviews of these brackets over the years, and everyone reports a noticeable change. its still just about the quickest and easier to fit 5% power/ economy upgrade you can buy for these

i have just ordered one for a 93 4.0 sovereign. which is the same bracket as AJ16 apparently.
need to wait for one for a pre 93 AJ6 though.

how about one for a 6.0 Andy?

[ptjs1]

naki,

Without wishing to question anything that Andy has told you, I'm confused as to why you can get a bracket now for a 4.0 XJ40 but not for a 4.0 AJ6 XJS. It's the same engine and would surely use the same bracket.

Are you sure that Andy doesn't think you've got an x300 4.0 Sovereign (which naturally does use an AJ16 engine) rather than an XJ40 4.0 Sovereign?

Paul

[naki]

naki,

Without wishing to question anything that Andy has told you, I'm confused as to why you can get a bracket now for a 4.0 XJ40 but not for a 4.0 AJ6 XJS. It's the same engine and would surely use the same bracket.

Are you sure that Andy doesn't think you've got an x300 4.0 Sovereign (which naturally does use an AJ16 engine) rather than an XJ40 4.0 Sovereign?

Paul

here is the info i received from him.

"We currently have brackets in stock that will fit an AJ6 engine in an XJ40 after VIN 667829".

so its relative to VIN range, not simply whether its AJ6 or not.

[AndyStodart]

The bracket that I specifically designedto replace EBC5017 on the AJ16 engines will also fit directly onto late AJ6 engines. In the case of XJ40 it is cars after VIN 667829. In the case of XJS it is engines after No. 161587 ( I haven't been able to relate it to a VIN, but the engine number is almost as easy to check anyway).

[ptjs1]

naki / Andy,

Tks very much for that. Something else for me to add to my knowledgebase!

I'm intrigued as to why they changed the brackets at these points. Particularly as the sensors themselves apparently changed design at different change points to the brackets.

It's also strange that Jaguar Classic Parts quote the bracket change point at a VIN number on the XJ40 but an engine number on the XJS. On the face of it, it seems incorrect to quote a VIN number as the engine build numbers do not follow strictly in order for the VINs for either XJS or XJ40. We know this from our own records. So a change at engine number seems more appropriate but, hey who knows what the Jaguar build records really mean!

In theory, an AJ6 4 litre engine number of 161587 approximates to an XJ40 VIN of about 664xxx so I wonder if an XJ40 after that and before 667829 really does have the old bracket? I'll see if we can find owners of XJS and XJ40 around these changepoints and have a look at their brackets.

Tks again Guys

Paul

[naki]

as always with jag parts. its confusing and full of exceptions to rules!
i really think around this era,. the parts departments/ designers/ suppliers were really trying o make themselves extra work!
XJ40 especially has an incredible number of parts changes across the production span.

[AndyStodart]

Having done some more research on crank sensor brackets, it appears that on early XJ40s up to engine number 108834 this part was EAC6001. I've never seen one of these parts, so I've not been able to make an equivalent part to give an extra 5 degrees of ignition advance. One of my revised designs of bracket is intended to replace EBC 1253 which was fitted to engine numbers 108835 to 161586. I make these brackets only when I have sufficient enquires. From engine number 161587 onwards the crank sensor bracket was EBC 5017, which was also fitted all AJ16 engines. I get most enquiries for this design of bracket, so always try to maintain a stock of these parts.





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[AndyStodart]

Recently I have been doing some more research to try to determine when Jaguar changed between different designs of crank sensor brackets, so that I can advise owners, whether I have designed an alternative bracket. It appears that Jaguar started fitting a bracket marked with the part number EBC1253 to 4.0L engines from engine number 108835. This part was fitted up to engine number 161586, which was about XJ40 VIN 667829. I have designed a replacement for EBC1253 which provides an extra 5 degrees of ignition advance. 4.0L AJ6 engines after number 161586 were fitted with a bracket with a part number EBC5017. This bracket was also fitted to all AJ16 engines. I have also designed an alternative to this bracket with an extra 5 degrees of ignition advance. These engine numbers and XJ40 VIN should only be used as a guide. The only way to be certain if a bracket is an EBC1253 or EBC5017 is to have a look at it. Hopefully this information will allow any XJ40 owners reading this to see, if they can fit one of my revised brackets. I might be persuaded to design revised brackets for 3.6L engines, but I would need one of the standard brackets from one of these engine, on which I could base my design. I would also need to know that there was sufficient design for such a bracket. I have had to disappoint a number of 3.6L XJ40 owners and 4.0L XJ40 owners with engines before 108835.

[ptjs1]

Andy,

I'm sure this will help owners. It also clarifies that owners should look at engine numbers not VIN numbers in determining the change points.

I think it would be really helpful if you could write a similar post on the same-named thread in the XJS section of the BB, to help the XJS owners?

Most owners should know the difference as to whether they have an AJ6 or AJ16 engine. However Jaguar seemed to want to confuse owners by starting the numbering of the last 6 digits of AJ16 engines with lower engine numbers than the last AJ6 engines. To clarify, AJ6 engine numbers end at 16xxxx but AJ16 engines then start at 100135. Confusing!

Also, do you know much about the different types of sensor? According to the Jaguar parts website, there are 2 different sensors used on 4.0 AJ6 engines but the changepoint doesn't tie up with the changepoint of the brackets. There are also 2 different sensors for the AJ16 engine, but I don't know if they are interchangeable as the bracket itself doesn't seem to change.

As always, Andy, thanks for your work on this.

Paul

[AndyStodart]

Dear All,
Contrary to my previous post it now appears that crank sensor bracket EBC1253 was fitted from 3.6L engine number 108835 to 4.0L engine number 161586. I can therefore provide a revised version of this bracket with an extra 5 degrees of ignition advance to any of these cars. Crank sensor bracket EBC5017 was fitted to all 4.0L and 3.2L AJ6 engines after 161587 and to all AJ16 engines. I can also provide a revised version of this bracket with an extra 5 degrees of ignition advance. I currently have stock of both designs of revised bracket, if anyone is interested.

[AndyStodart]

Anyone who attended my presentations at the JEC AJ6/AJ16 Engine technical seminar will know all about this modification. It is the easiest and most cost effective way of which I can think, to improve performance and fuel economy. I have now made over 450 of these brackets. The latest batch of parts (replacements for EBC5017) were finished this week. Anyone who wants one should contact helenstodart@gmail.com

[YoungX300]

I've had the mod since January this year: does exactly what Andy says, adds power and has increased my MPG by a bit at the same time, would certainly recommend.