'5006, that's pretty damned cool!


So, exactly how are those primaries set up on the exhaust? I was look at that pix and can't figure how you have 3 into 1 there. In fact, it looks like I am seeing 7 (!) primaries somehow.


Did you ever see this setup: 3x4:1 it's bizarre, but it you follow those pipes closely from the pix and look at the firing order, you can see why they did it.


Burns Stainless LLC - 6-Cylinder and 12-Cylinder Exhaust Design


Loved the sound of those Matras, too.


Cool, nice work!

 

Ronbros I'd like too kmow where your pulling the 96mm bore out of? Your a** maybe? ? Last I checked its 90.mm bore so if you get a decompression plate with extended liners a billet or steel forged crank it will reach 91mm bore and 91 mm stroke . And ! In you were too machine your own decomp plates you would be able too match the coolant ports too the head you'll allow more surface area too be around the cylinder and no more blown head gaskets even under boost . And yes I have full acess to a cnc machine

 

I have 96mm bore in the stroker I built the liners come from rob beere racing

 

Defo 3 to 2 into 1, yep see what you mean about working it out, I'll see if I have a better pic.

 

got to thinking, i'm saying you cant build a Jag v12 with 96mm bore and a 96mm stroke unless you got 50K or more to spend!

at some point all seems like and effort in futility.

BUT, sometimes you gotta get out and move around, back(2-3)yrs i was at a PRI show in Orlando Fl.
at the GM space(almost fell over) was an LS V12 engine, now that would be interesting, already comes with a 100mm bore, stroke i donno.

i thought it was two blocks and heads WELDED, no they were cast in Germany, and the guy said they(GM) had a Cadillac LS V16,(16 cylinders), already up and running.

question; why not get one and put it in a Jag with Jag stickers on the covers,hehe most woudnt know anyway, guy said it made 750hp(v12,v16 1000hp) no problem, and with its modern lube and power systems, dependable and great variety of heads, many parts over the counter,like pistons,rings, bearings, valves , etc .

if i could afford things my best choice for a 12 cylinder engine would be a used AUDI V12 diesel comes from factory with twin turbos,direct injection, makes an easy 600hp but with a massive 800lbs ft torque, and again dependable and economicle MPG.

and figures show the Audi is lighter than a Jag V12.

do you think a 96-96 Jag would be dependable at full output?

for kicks,google LS V12and LS V16, a guy in Seattle is welding 2 blocks and heads together, like icsa says LS engineering is some of the best for money.

 

hey 5006, love your new car, makes my think back around 88-91 Rolex daytona sports car races , bought a tee shirt,still got it.

 

Hello I need your help or advice.
Briefly about my car: XJS 1993 V12 6L, transmission is 4speed 4L 80E, differential is 2.88. wheels is 275x45R18. ECU is stock 36cu
Produced increased throttle (flap from XJ8 4.0, throttle body), porting the intake manifold to 35 mm, set them in bell tube, also porting and head up to 35mm. Silencer also increased, almost cocurrent (why almost because very loud), 74mm from exhaust manifold to end.
Yes, of course the engine began to accelerate significantly better, become more responsive to the gas pedal, but there is not 7 seconds to 60mph at best 9 seconds. From 0 to 20mp h acceleration kind of bouncy, further as if the attenuation begins acceleration dynamics.
Motor spins up to 7500 rpm, and all this on the first gear up to 70mph, fuel pressure steadily from 2.5 to 3.0 bar. So what do I do next? Velocity measurements were made with GPS and simply stopwatch.

 

xjsv12,

Fitting larger throttle bodies, and port-matching your heads, as you have done, is always a great way to uncover extra power by allowing your engine to breathe better. Your larger, free flowing exhaust is another goldmine for additional horsepower. However, doing so has also moved your torque curve higher up in the rpm range, which is much better suited to top speed, than for 0-60 runs, or stop-light drag racing. Increasing the airflow through your motor also created a lean condition which may be outside the pre-progammed parameters of your stock ECU, thereby starving your motor for fuel. This may partly account for "bouncy" low speed acceleration that you have been experiencing. Improper throttle linkage adjustment may also be a culprit for this condition when the butterflies are first opening up, as this is when proper adjustment and synchronization are most important.

If I were you, I would first check the throttle linkage adjustment, and correct it if necessary. I would also buy an air/fuel ratio gauge like this one to monitor your air/fuel mixture. If you find a problem in that area, I would consider sending my ECU to Roger Bywater of AJ6 Engineering AJ6 ENGINEERING, to have him calibrate and remap your ECU to match the modifications you've made to your intakes, cylinder heads, and exhaust.

Because you are interested in fast acceleration at low to moderate speeds, and better 0-60 times, you may also wish to swap your 2.88:1 differential for a 3.54:1 from an I-6 XJS. A manual transmission would also be an excellent modification, allowing you immediate access to your new torque curve.

Best of luck to you on your continued quest for speed, my friend

 

You are running real long legs there; so a 0-60mph will be slowish. Never heard of anyone who got 'real' improvements with an AJ6 system, all too old hat in my view. Try increasing fuel pressure with an adjustable pressure regulator if not already fitted. Better still get a lambda sensor and gauge fitted and see what it says on full throttle. Increase fuel pressure to compensate for any deficiencies. It will hurt fuel consumption but not as much as a burned piston will hurt your wallet. The real answer is a mapped ECU. lots about nowadays but so much cheaper still not that cheap when someone else fits and maps it for you. You play you pay.

 

Never heard of anyone who got 'real' improvements with an AJ6 system, all too old hat in my view.

Better still get a lambda sensor and gauge fitted and see what it says on full throttle.
You mean this:
Aem 30 4100 Digital Wideband Uego Controller Air Fuel Ratio Full Warranty | eBay

Or can simply measure the oxygen sensor with a multimeter?

 

best mod you could do is a lower rear axle ratio.

2.88 and overdrive is useless, unless you going for 200+ MPH and no acceleration.

and like any hi-performance vehicle,it always about the TUNE UP, and engine adjustments.

acceleration requires low rpm torque, not so much hi rpm hp!

most of your mods are directed toward hi end hp, what have you done to increase torque at the tires?

 

Thank you all. I'm on the right way.
Firstly. ECU is necessary to deceive! Will make measurements of lambda. Lower air and water temperature sensors . Will play with fuel pressure. And also with the tube MAP.
Secondly. Transmission already purchased and ready for fix. Low gear and TCU ordered from TCI.

 

ECT is not very sensetive.
first picks is normal mode. 90' (194F) air 57' (134F)
second is manualy droped to 77' (177F), No effect on the lambda.
if I fall below 77' , check engine is coming.

 

IAT is more sensitive.
Changes in air temperature greatly changed the engine even at the hearing.

 

I always went with KISS (Keep it simple stupid) Had a basic gauge and sensor, took the car to a strip and had someone floor it whilst I watched the gauge. if at any time the needle went into the red we would up the pressure by 1 or 2 psi and go again. On the Pre He we usually ended up with 33psi on a nice std engine and 37ish on a well worked one from memory. The 37 psi was good enough to win clubmans championships. No burned pistons but she would cough and splutter and kick out flames on the over run! Now older and wiser (and with more money) I would go mapped straight away, but not before moding the std rods to Group A spec + many other little bits. You dont even have to take the heads off. Drop the sump, take of a rod cap and weigh it (in grams as its easier) machine or linish 100 grams from the balance pad (or whatever you are happy with) then clean are replace, replace the bearings at the same time if you find wear; loose 100 grams from each cap in turn and you will have lost 1.2 kilos from the reciprocating weight. A nice light weight flywheel also works well or a smaller diameter converter. No increase in power but she will rev much nicer and accelerate much better.
+

 

'5006:


Would you post a pix of the mods you described for the rod caps to Group A spec? I certainly like a balanced reciprocating mass, but taking 100 grams from each rod end seems like a lot, and I'd want to be really careful of just where from and how this was done.

 

The factory rods are crazy heavy, I went with Manley sportsman rods when I built the stroker motor. Which way only 535ish grams a piece

 

Has the diff been replaced then? I thought all 6.0ltr cars with the GM4L80E box had a factory 3.54 differential.

A.

 

My XJS 1989, but the old 5.3 flew away and burned. I bought and modified 6.0. I like a 2.88 for the high speed and slow RPM. I will modify the gearbox.

 

Might have a stroker 92mm crank available if anyone is interested. Never fitted , all bearings std, requires a 5 mm spacer plate. PM me if interested.