Hi All
i am looking to work out the differences between the AJ26 and AJ28...

i have an N-A 4.0 V8 from an S-type that i am planning to strip, rebuild and add an XKR Supercharger...

i have test fitted the supercharger, and everything seems to fit perfectly...

i am binning the old dodgy water pump and going to an electric Davis-Craig EWP150 with controller.

i am also binning off the power steering, and AC. the Engine is going into my Lotus Excel, target is 450bhp with 900kgs dry weight.

any advice on places to buy stuff, and what the differences are in engines between the NA and supercharged and AJ26/AJ28 are appreciated.

i understand my AJ28 4.0 has variable valve timing which the supercharger cars didnt, so i would like to bin that off as well... i assume its just a cam change?
















also any jag parts suppliers near surrey/hants/west sussex borders? and what do i need other than removing the cats, and upgrading the pulleys to get to 450-500bhp?

i will be using an emerald ECU in wasted spark config for engine management.

having an adapter made to take a supra clutch onto the jag flywheel, and mate it to my Toyota W58 gearbox thats already in the car.

Many thanks!
Oz

 

can anyone tell me the engine differences in the N/A 4.0 V8 vs the Supercharged V8 in the S-type R...?

my understanding is the NA has variable valve timing? the supercharged doesn't?

can the NA be converted to the supercharged spec?

whats the compression difference? anyone retro fitted a supercharger to the NA lump?

My xkr supercharger fits the inlets and manifolds on my AJ28 (s-type) NA 4.0 perfectly...


thanks!
Oz

 

The 4.0 was never SC. The 4.2 is the one that is both NA & SC and no it can't be converted for a ton of reasons - sell and buy the SC (STR).

The STR got VVT after a while, to reduce emissions.

 

Ok, will just get some 4.2 heads and cams then...

I'm sure that I heard of a VVT deletion kit...

The emerald k6 can handle the VVT on the rover k-series so should be able to do it on the v8 too... It's also fully canbus compatible and I will be building the loom myself for the cooling and fuel system.

Do you know what parts differed from the 4.2na and 4.2 supercharged then?

Thanks!

 

Wasn't there a 4.0 supercharged xkr on the aj26?

 

Yes there was but not in the S Type.
I think you may have got a different answer if you had explained fully what you are planning.
I've copied your post here but think it might be better to move the whole thing to the XK8/R section or the XJ/R one

 

Thanks.

I posted separately here as the 4.0 na block I have came from a 2001 s-type that I rescued from a farmer who pretty much killed the rest of the car...

I wanted to work out the quirks of the s-type/aj28 lump vs the xkr's aj26 lump.

Any advice appreciated!

 

There's a thread in - er, one of the forums! - about (mechanical) engine differences.

(The 4.2 NA / SC is AJ34 / AJ34S (hmm, AJ33 anyone). I suspect you don't want to go into all the tweaks.)

The big issue is what PCM are you going to use? Not a simple issue if you wanted to use any of the jag ones.

Also... what gearbox...

You might be wise to read the various previous threads along similar lines as people tend to think this is easier than it is.

 

John, did you look at the first post? It's new since you were last here, copied from general tech, and gives a lot of background detail.

 

the 4.2SC has 9:1 compression, the 4.2 NA is 11:1.

 

Thanks. Being new hear how do I find said thread? Quick search hasn't found it...

Also I think the issue others have is trying to run the auto box or other jag systems with the engine that causes all sorts of canbus and check sum errors.
Doing the loom from scratch with a standalone ecu on an older non canbus car I think I will avoid most of the previous pitfalls. Also my best mate is a somewhat gifted roboticist and auto electrician, and I am a home automation control systems programmer and game developer.

Won't be quick, but should be doable!

 

To get the extra compression on the STR when under boost they had to change the engine. If you do similar boost to the NA you can expect to wreck it.

Whether it would happen soon or not... don't know. Are you OK if it happens soon?

Search on some obvious terms, maybe using google, should get you more threads.

(Good grief, where did those earlier posts come from!)

 

Yep I am fine with that. Will start boost at 0.7bar and work up

 

That's good then, I still think we are in the wrong place to get the best advice, I'm going to PM a couple of members who might be interested in your idea and see what happens.

 

Awesome thanks!

Any help is appreciated! I have quite a long way to go on the project so still collecting as much info as I can absorb!

 

Adding boost on a NA engine will almost instantly put it into detonation territory. How will you deal with that?

 

Plenty of NA motors take bolt on forced induction kits... Look at all the booster Civic Type R's, or Mx-5's (Miata's if you are American)...

You just compression test the engine first to make sure you are starting from a solid platform and start with a low boost... If it's a real issue and you don't detonate the engine then you put in a spacer between the head and the block if you want to lower compression.
Or port the head out and change valves and re-cut the valve seats...

I'm going with the start at low boost and hope it doesn't become a bomb approach

Once it's running, then I will worry about making bigger power and upping the boost later. Another v8 is pretty easy and cheap to source if I do blow this one

 

Well, you didn't answer my question so I'm not sure you've thought the issue through or understand the challenge.

Neither of the two other cars mentioned have plug and play supercharger kits suitable for high compression engines. Page after page of discussion recommends not supercharging an 11:1 engine.

 

See https://www.jaguarforums.com/forum/x...d-works-49685/

and

https://www.jaguarforums.com/forum/x...ed-xk8-127904/

 

I think we are being too negative, this is not someone wanting to supercharge an old S Type, the plan is to supercharge a NA 4.0 motor in a Lotus coupled to a manual box with a bespoke engine management system.
Ozzy_ UK has also said it's not the end of the world if it blows up.