Tim, doing what you are after is not as simple as one may think. By forcing more air into the engine, you are causing the cylinder pressures to rise. While this is good for squeezing more air/fuel into the cylinder, it can lead to pre-detonation (diesel effect due to pressures changing too fast). So, simply adding a turbo to the motor is not going to be the best idea. While I am by no means an expert on the 4.0L motor, I think you are going to find the compression of this engine to be too high for your use (motor I believe is up around 10:1, for a turbo, you are really looking for about 8.5:1). So, this is going to involve a complete engine tear down (which would be recommended for a modification like this else the engine is going to give out shortly there after due to the changing stresses in the engine). This also can be made more or less difficult based on the year of engine. You don't state the year of your car, so, that might be some vital information to those that know the blocks and their finer details.

I'm not going to question why you are wanting to do this, but I also want to stress that there are a lot more purists when it comes to Jags than most other brands. So, don't be surprised if you get a lot of negative feedback from doing this modification. This will be especially true if you try to show the car off in a car show, especially one focused around Jags. I have seen it happen. Please don't take this as a "DON'T". But, understand what you are getting yourself into.

 

I agree.

Besides, it's SO easy to go out and buy an XJR/6. Supercharged rather than turbo'd....but all the bugs have been worked out :-)

Cheers
DD

 

Yea why would you put a turbo in a classic like the x300?!!! Makes no sense! go get an xjr and problem solved!

 

Yup, that's the idea

 

I know this is an old thread, but I just joined and would like to see what timlibala has come up with I kind of have this same idea, but basically it seems like the easiest thing to do is get an xjr engine/ecm/fuel pump/pressure regulator/transmission and if one is going that far, they might as well just throw in the intake manifold with the intercooler built in and the supercharger. Maybe buying a wrecked, complete xjr would be the best course of action. I'm contemplating this work because I only paid $1800 for my VDP, I am a DIYer and have no problem fixing it up the way I want to.

 

Othatoneguyo
Having heavily modifed my XJR6 by fitting an Eaton M112 supercharger from an XJRV8, I am all too familiar with the reaction of some purists who don't think that anyone should modify these cars. However, having worked for Jaguar on the development of the XJR6, I know that the AJ16 engines have a huge amount of potential for performance upgrades, if done properly. With modern turbochargers it would be possible to increase the perfoamnce of an AJ16 well beyond the levels achieved by a std XJR6 engine. An inline 6 cylinder engine with 7 main crank bearing is architecturally one of the best base engines to upgrade. The Jaguar AJ16 engine has very large 76.2mm main bearings 22.5mm wide with Vandervell VP2C tri-metallic shells. The main bearing panels are solid with no bay-to-bay breathing holes to cause stress concentrations. The block uses iron liners, which whilst not the optimujm solution for heat rejection are more durable than parent metal bores. The big end bearings are 53mm diameter and also 22.5mm wide. The std crank is a 12 weight forged steel design. Despite its large 51mm throw it achieves reasonable pin to mainbearing overlap by virtue of its very large main bearings, so i think the crank should be strong enough. 6 cylinder engines are ideally suited to twin turbocharging as with modest period cams like the std 242deg cams , there is negligible overlap between exhaust event on the cylinders feeding each turbocharger. This avoid the "cylinder stuffing" issues which affect I4, I5 and cruciform crank V8s. All-in-all this is a very good basis from which to start a major engine performance upgrade. However, in my view it would be essential to drop the compression ratio from the std 10.0:1 of a naturally aspirated AJ16 engine. If you started with a supercharged engine then you would have an 8.5:1 CR. However, if you were aiming for say 500bhp them I would recommend custom pistons with a 8.0:1 CR. Obviously this would be a major project but I think the engine could be developed to produce 500bhp. I already run my engine at torque values, which if achieved at 5700rpm would produce 500bhp. A pair of well matched turbocharger would be able to provide sufficient airflow to achieve 500bhp. For anyone who questions that such a power output would be posisbel from a 4.0L 6 cylinder engine, I would refer you to the 3.8L VR38DETT engine fitted to the Nissan GTR or the 3.8L Porsche Turbo 997.

 

Thank you XJRengineer.

I have no doubt about the capabilities of the aj16 engine. If I were to go through with my plans, my goal would be 400-450hp with the twin turbo. Just a couple more things, though. Can you tell me where I might find aftermarket or just performance parts for this engine? Camshaft, forged pistons, etc... or would I have to go to a machine shop to have custom ground camshafts and pistons made? And would the factory intake manifold with the built in intercooler be enough to cool off the hotter air from the turbos, or would aftermarket be better?

Thank you for your time. As of right now, all this is rhetorical since I just bought my x300 and don't have any money to put into it yet.

 

There is virtually no market for performance parts for these engines. AJ6 Engineering (UK) is the only company that I know of that used to procue aftermarket parts for AJ6 engines. I'm not sure if they make anything for AJ16 engines. The std 242 period cams wouldn't be ideal, but would probably do or you could try getting them reground. You could try the cast 8.5:1 pistons from an AJ16 SC engine. If yo machied the bowl deeper to drop the CR to say 8:1, I think the crown thickness would be marginal.

If you ever go ahead with this project, then contact me directly, as I may get a custom set of 8:1 pistons made myself.

The intercooler isn't bad given the package constraints. You will have plenty of other things to change, so if you want to limit the costs I would carry on using it, but fit a higher flow rate inercooler water pump.

Good luck with your project

 

Thank you for the info. I have a lot of research to do before I commit to this project. One thing I'd like to find out is if there is another manufacturer that has a forged piston that can be milled to plug the cylinders. Even if I have to bore the block a bit. I already know a machine shop in town that says they can custom grind any cam, so that would be the easy part.

 

I had custom forged pistons made for my stroker Essex V6 (going from 3.0 to 3.8) made last year
I am also using of the shelf 5.7 inch h beam rods CRS5700B3D 4340 Steel H Beam Rods - Small Block Chevy | CRS5700 | Johnson's-Quality-Machine.com
The pistons I used came from arias AriasPistons.com

When I finish doing up the Capri I am going to build a Suffolk SS100 replica I will be building a hot 4.2 to go in it going to stroke and bore it as well easy way to make power reliably

 

Nice! Thank you. I bookmarked the Arias Pistons website. Would you mind telling me how much your pistons cost you?

 

using a 0.060" head gasket drops the cr from 10 to 9.4
then i could run 8 psi on the x300 and get about 360 hp.

but, if i take the head out to change gasket, i might mill the combustion chamber deeper.see any problem taking 0.40" to 0.60" from the top of the cc?
then i could get the cr down to 9 or even 8.5 and output up, over 400hp

simpler would be to change the pistons and use xjr pistons. would they fit ok?

 

The pistons where not cheap $1200 AU
The guy that is building my Essex engine is really in the know on these engines he even makes parts for the UK specialists like Ric wood and Burton's

The pistons for my Essex where also 180thou oversize with the stroked crank took it from 3.0 litre to 3.8 litre just trying to get some bigger Webber carbs now as the standard triple 40 dcnf,s are a bit small trying to get some 44,s but they are extremely rare


if you look at my post re the XJR tornado they bored it to 4.2 litre no substitute for capacity
Paramount is still in business although if you order the pistons through them you will need a chair to catch you when you faint from price they quoted me 2500 UK pounds for headers for an aj16 engine
I actually sell my ready to install 304 grade aj16 headers for $1700au without shipping and their headers don't have fittings for oxygen sensors

If you could get hold of there piston design it would save money you could take it to Arias as for turboing the car I would more likely fit a pro-charger S/C these are a centrifugal type when I fitted one to a 99 Lincoln navigator it made 550HP at all 4 wheels

 

By my calculation, a 1.5mm (0.060") thicker gasket adds 9.7cc and would drop a 10:1 CR 4 litre 6 cylinder engine to 9.0:1

You can fit AJ16 SC pistons (if you can find any - they are NLA from Jaguar) into an NA engine to give a nominal 8.5:1 CR but I would suggest it would be easier just to swap the whole "long engine".

 

HEY GUYS, heads up!

i dont know who timibala is but he is using my garage and 1975 XJ12c for his stuff, me thinks he is a scam!

 

Now when I click on his garage I get my own car as well I think the site has been compromised

Any moderators watching check this out please

 

He's no longer registered with the forum, that's why he shows up as a Guest & you can't see how many posts he made.

When a poster is a Guest, you see your own Garage in place of his.

It's been mentioned a few times here on the forum now. Any posts by a de-registered member i.e. Guest shows up your own Garage. It's normal...

 

i think i assumed in my cr calcs that the existing gasket is .040 or 0.020 i do not remember exactly, but if you arr right then that's the way i'll go

 

Plus, I heard the xjr head was built a bit stronger as well. Ideally I would start out with a used/scrapyard xjr engine and go from there.