The first time Ronbros mentioned this I looked on ebay and saw just an engine at $10k. No telling what the final bidding went up to. But yeah, it's an intriguing swap. I haven't seen one for sale since...

 

anything beyond the normal, would be expensive and rare.

but the final results would be so KOOL, and you could say no one else has one!

its all about the Ego.

like iv said before no one needs 12 cylinders(really).

 

Ron,

An Audi 6 liter V12 diesel sounds pretty expensive right off the bat. What vehicle did Audi put those in?

 

The Q7 got that engine... Polluting piece of VAG crud...

 

Keep up the good work!!! How can you not smile at the idea of a quad turbo xjs

 

I do!!

 

Audi Q7 SUV TDI, but says V12 on the front and rear, we get them in usa 3.0L V6 TDI, no comparison of performance. never said they are cheap,yno, you get what you pay for.

Utube some of them, some of them matching BMW M5 petrol, but way better mpg.

Diam , you think your V12 XJS is not a polluting engine? and your mpg aint all that good.

 

Flint , yah gotta agree, i like my Jag V12, but it would blow peoples minds,raising the hood
and a 500hp V12 diesel sittin there, twin turbos, twin intercoolers, direct chamber injection(most here dont even know what that means).

 

mike Audi did put the 6.0L V12 diesel in an Audi R8 coupe, Quattro drive,

they decided nobody needs that much road vehicle, worried about drive line warrenties, DUH, i imagine so!

 

Hi Shaun

Just wondering, I had a twin turbo Legacy GTB, this ran a similar sequential setup, made 15psi boost at 1500rpm but had massive turbo lag in the midrange when he second turbo valve opened. How will you overcome the spooling of the second turbo issue.

 

My XJ-S emitts CO and CO2. No NO, NOx, no soot, no ultra fine cancercausing particles... Oh, and MPG isn't everything. Considering I get a good 12l/100km in my XJ-S V12 noncat... That is less than say a younger Audi V8 (not A8 or so, the first Audi with V8 was the Audi V8) can do... So technically: there are a lot of worse cars out there than an XJ-S.

 

Warrjon, I don't think Shaun's turbos are sequential. Each one is fed directly from 3 cylinders. OP, feel free to correct me if I'm wrong. I have a marginal understanding of these things.

 

According to Allan Scott's book one problem TWR had with the XJS Group A was the heads lifting causing gaskets to blow.

Your larger head studs may fix this though.

 

I just made the assumption because he talks about compound boost, one turbo feeding into the other.

 

I would think that would be more up to a difference in torque, not size/strength. I have never looked at the specs, but being the the 70s and using studs, I expect the XJS uses a torque specification, is that true?

Correcting the problem would more than likely involve tightening to plastic deformation instead of elastic, in other words, torque to yield bolts.

 

compound turbos is NOT like sequentual.
with sequentual 1 turbo cuts out then second cuts in.
Creating lag in the change over phase.
With Compound all turbos run all the time.
small primaries bleed off to prevent overspool while feeding directly in the large
before exiting the car. large turbos feed boost directly into primaries to double boost pressures (sort of) so even at lower rpm you can still maintain even boost.

Just got back into the country after flying to SA for wedding then bali for holiday then UK for funeral so at this stage my funds are well in the red.
Got the repaired lathe motor in and wired backup. just need to reposition lathe back into its slot to commence work again.
Hope all is well with every one and jags not dieing ungracefully

 

Head studs stretch under normal conditions regardless of power, positive pressure (boost), just makes it worse. A stud such as ARP would need to be used in any motor that's making any sizable amount of boost.

The next issue to consider is the floating liners, not sure longevity would be on your side without evaluating the same under boost. I've lifted heads on approx. 25lbs of boost (proper head studs, etc.), evac'd an entire coolant res in the process too (that'll get your attention, thankfully was on a dyno). ;-)

As for the Legacy being laggy, am assuming your displacement was fairly low. The 5.3, if matched to the proper hot side, should be lag free, stepped turbos, even better.

Cheers,

Jeff

 

would be nice if someone on this site actually did turbo a JAG V12, just so we can see what works and what doesnt!

i.m retired and sold my machine/welding shop, so i doubt if it'll come to pass with me.

i got a ton of ideas! like 65yrs worth.

 

i was looking at a BMW with triple turbos on an in-line six,factory, somewhat complicated but says it wroks great, no lag and plenty of torque and power.

 

a few yrs back on this site, i tried talking about rear mounted twin turbos in the area where the mufflers used to be. most said noway wont work, much turbo lag.

i have done 4 vehicles with remote turbos, they all worked very well ,its all about sizing and tuning. easier than you think.

frees up a lot of under hood room, and big reduction of under hood HEAT, little short pipes out the rear off the turbos, sound nice no mufflers(turbos act as a muffler).

well google KIA 900 twin turbo, or LUX motorwerks(they did the mods).