Shaun. I think this project is awesome. Please keep us posted as it progresses.

 

Shaun,

Thanks for posting an update. I'm trying to imagine how all that plumbing will be routed in the already tight XJS engine compartment, and grill area. I'm certain you'll figure it out with patience and planning, if you haven't already.

The thing(s) I'm really curious about are the pistons. I see your reasoning in the piston profiles, but, I've always heard that cast pistons and rods won't hold up to turbo duty, and, that only forged components will stand up to high boost pressures. While the crank is forged, Jaguar, in their infinite wisdom, decided to go with cast pistons and rods, for some reason. Having to swap those internal components (whether for lower compression, or for strength) is what makes turbocharging this engine so expensive, and such a pain in the a$$. Are you going to use the stock cast pistons & rods, or, will you use forged versions of the pre-HE (or 6.0) pistons & rods?

Also, your photos don't show where the air charge will enter the plenum. Is it on the back, or will the plumbing arrangement determine the location?

Looks good!

Please keep us posted, as I don't know of anyone who has gone beyond the planning stage for quad turbos on a Jag V12. It'll be great to see a working version of what so many Jag enthusiasts (myself included) have dreamed about.

 

Hi..
yes you are partly correct on the air intake.
It will enter roughly between 4th and 5th intake on each side.
the reason its not in yet is i need to set the injectors and fuel rail to determine the maximum clearance.
air intake will be facing directly forward and over the rocker covers.
these will be bolt on and off to allow access to injectors and fuel rail.
the mounting plates for these have been the latest thing made.
not that they look any thing at the moment.
4 matching plates with tapped holes for allen key bolts made out of machine grade alloy (to cope with threads) but untill the injectors are in position i cant cut out the air intake and mount the plates onto the plenum.
i refused to pay $15.00 per injector boss for a scrappy bit of alloy (x12)
when a lathe was on order. (arrived today) now reorganizing my shed (not that it ever is) to make it fit and have room to weld, swing the cat and dance around the jag when i drop something on my toe.
Also keep in mind with the jag that nearly all the bolt on components will be 1996/7 GM Aircon compressor,altanator,powersteer pump,
logic for this is serpentine belt. and smaller units.
power steer pump is remote reserve tank meaning it will fit under LH turbo and get tank away from heat (behind headlight) the serpentine belt should gain me approx 5 to 6 inches at the front of the motor for piping and radiator.

 

many people under estimate the strength of the V12 components.
GM rods (cast) with smaller big ends handle boost quite well.
Keep in mind the jag engine was designed for 10,000 rpm runs in its original form. This hi RPM causes more stress than boost will at 5000 RPM or even 7000 RPM.
non of the bottom end was ever derated from this.. it was the top end that stopped this in production form. the flat top pistons are not the best option as the top ring land is fairly close to the top but even so they will handle boost up to about 500 HP.
Most turbo piston failure is air fuel mixture not boost its self . yes forged is better but it is NOT the be all end all. look at what the rice burner get, get out of there stock components now spread that over 3 sets of pistons and the jag is looking better every day.
i have a few friends that are designers/inventors in there own right (one is getting royaltys from landrover) and once my system was explained to them slapped me upside the head and said i am aiming to low in my estimate of 1000 HP. one rang me back after a week of thinking it over and said 1600 HP or he wants to know why not.( I think he is on drugs) as fuel delivery becomes a huge issue after 800 HP.
But yes there is a definate likely hood of me melting down a V12 motor.
but if our boys here in perth can get 700 plus HP out of a 3.8 litre v6 with stock bottom end the surely a humble JAG can get 1000 HP out of a V12.
Shaun

 

only time will tell,(course lots of money), but if you are spending on tig and machinery, means you are serious!
i think you enjoy building it,maybe more than will driving it!


those Buicks and other GM V6s, turbod may make serious power but they can be fragile, blown a couple into the next county, finally put an LS3 into the buick, no more worries.


all and all, i do like my V12 , seems to be a pretty rugged motor, but i aint boosting it, done many turbod/supercharged engines ,and learned a lot!

tuning is the most important part of the equation!

 

Amen to the comment on tuning.
tune the baby til she sings then keep tuning cos you ain't done yet...lol

 

added info; the guys that raced Jag V12s when pushed to ther limits 1984-87, had cracked or broken main bearing caps, cast iron, so ended up custom making steel caps, one guy made the caps from hi-level bronze!

slightly flexible, to reduce cracking!

i would imagine 1000hp would put some stress on cast iron main bearing caps!! ??

of course you could make a one piece girdle lower end assembly!! WHAT?

 

thanks for sharing mate

this is gonna be awesome!

 

brought and installed new lathe.
machining up dummy injectors (to line up fuel rail as i weld injector ports in)
and i hear a POP and a huge cloud of smoke pours out of the back of the lathe.
so i pull the power investigate and come to the conclusion that the brand new motor has blown a winding or capacitor or something simular. so its move the lathe (650kg) to pull the motor to send to South Australia to wait for warranty repair.
And that guys is how my week has gone..
Hope yours is beter.

 

Damn - sorry to hear that. At least it's under warranty, but the delay still sucks.

 

just remembered this pic i have in pix,

Mike Moran king of turbo engines, 2200hp back in 2003, he's now at 3000hp!

he originally used 4 turbos, but went back to 2 large ones, was difficult to make consistent results,(tuning etc).

nothing much just an OLD BBC,chevy

 

Insane!

 

Yep
Large twin turbo's produce More Peak power than Quad config.
but you need to wind them up. 3000 HP. real nice but how much below 3500 RPM.
The V12 config that i am playing with should be at about 450/600 HP at 3500 RPM. the small turbo's that i have are good for 380 HP each (peak).
my goal is to drive this on the street. most likely only ever see 1000 hp on dyno (if lucky) i will be happy with 600/700 every day. my config can be wound up or down as i choose. well that my plan any way....lol
shaun

 

Sorry to hear about your misfortune. I'm sure that's not the kind of barbeque you were planning to have this past weekend. Hopefully the repair will be quick, and you'll be back in business shortly. They'll likely just switch it out for a new motor. A 1,400 pound lathe goes a few steps beyond anything a hobbyist would need. You must have pretty big plans for future projects.

 

my personal plan for 12 cylinder engine in an XJS;

would be an AUDI V12 diesel 6.L, factory stock comes with twin turbos, twin intercoolers, direct cylinder injection, using a BUILT GM 6L90E auto matic trans.

factory stock make 500HP 700ft lbs, at a leasurly 5500rpm, torque is over 500lbs at 2200rpm(stock).

they have a chip available that pushes up to 650HP and 800ft lbs(that should get the job done).

and with only in a 3900-4000lb XJS ,MPG in the low 30s cruising!

also engine weighs the same as V12 jag, trans maybe 25lbs more, and you dont even have to take the engine apart to work on any thing, it would
be all in the ancillaries

as usual i'm outta the box!

 

I have wondered whether Lamborghini has sneakily tried one of those in an Aventador.

 

ok....sounds good..how many around and what price in a breakers yard

 

or even a VW V10 Tdi...

 

did i mention the Audi V12 has DRY sump lube system,factory stock!

and the VW v10 could maybe a usable idea.

 

Hello Shaun,

I've owned some pretty hairy 20 valve (twin cam) turbo five cylinder Audi's (north of 30lbs of boost, 2.2L making 500-600 CHP, streetable 400-500 WHP). That involved lots of intake, exhaust and bottom end work (Audi's 5 cylinder race program was getting 1,000hp out of some development group B rally cars on a test bed basis running 2.2-2.5 liters), not to mention standalone engine management, drivetrain upgrades, etc, etc.

I would urge to spend some time on the timing chain design and bottom end bearings, as both are going to take one helluva brain damaging once on positive pressure (more so than forged vs. cast rods). Also, you may want to consider running just two ball bearing turbo's, something like a set of Garrett GT30R's. The 5.3 makes enough torque down low, that I suspect with proper head and valve upgrades (and intake plenum capacity), you'll be able to make some fairly silly numbers and have limited or manageable lag. One other thing to take into account being the pressure reduction in intercooler piping, as the longer the run, the more the lag, and the XJS doesn't exactly have a huge area up front for a proper sized front mount, while still catering to the car's already inherent overheat tendencies (i.e. blocking airflow to the rad). Check out how Jay Leno turbo'd his nut job Olds Tornado, the geometry of that setup may give you some ideas and simplify the "what goes where" questions.

Interesting project and I wish you the best of luck. I've also blown up some pretty neat stuff along the way too (as you said, tuning, monitoring ala stand alone, and fueling are key to basic longevity). There is so much aftermarket and knowledge out there, your project is 100% doable, just don't let the math on the paper drive reality, I tried that once, and my wife still gives me "the look".

Embarrassing all but the ridiculously built iron with a four door sedan was priceless. Being AWD, and able to lay four rubber tracts the size of Texas while the guy in the Vette's jaw feel off, was always a fun endeavor..

Cheers,

Jeff