I see XJS v12s on local craigslist here as low as $1500cnd (not running) but...not running is often 1 sensor and a jerrycan of fresh gas, oh and a walmart battery.

If I had silly money I'd convert the V12 to diesel and pipe in a Ford 6.7L (Garrett?) Twin compressor turbo. I think someone here did the math once and said a combo of HE heads with flat-head pistons did 23:1 compression? Sounds like diesel territory to me.

or other way around but the gist of it was the parts from both could in combination produce high compression, the sort needed to get those diesel coal cannons firing.

 

That’s why it took from 1966- 1971 to develop a bigger version. Sir Lyons was looking at competing with 7-8 liters of American V8’s as his goal. There were cast iron blocks made but they were something like 130 pounds heavier than the Aluminum version. But the first versions of them still were quad cammed. The Heron head brought the weight, size, and cost down.

Compare what Ford spent developing their 427 to last 24 hours to what Jaguar spent with Group 44. or even look at Huffaker Racing and Group 44 with the XKE did on modest budgets. Effectively defeating the Decades of Corvette development.
Read JaguarV12 Race Cars by IanBamsey & Joe Saward. 1986 publication.
The engines themselves were remarkably reliable.
I won’t bore you with race by race details but a Distributor jack shaft failed on one. and valve springs would heat soak badly during pit stops of the Walkinshaw Group A cars ( cast iron exhaust manifolds) until better quality valve springs were used. ( incidentally Isky sells the same spring )

Overheating at Daytona you mentioned was due to a hole in the radiator from stones. Another year damage to the front bodywork reduced ducting to the radiator.
It’s true that Group 44 had trouble at LeMans but that was due to the French pump gasoline they were mandated to use. Group 44 had been using 110 octane racing gas previously.

Group 44 was going to 8000 RPM in the trans-Am / IMSA but reduced it to 7000 RPM for 24 hour races.
Engine power of the V12 had to overcome a 350 pound weight handicap (3150#’s)Jaguar had compared to Corvette weight of 2800 pounds. The second version with its acid dipped body panels was only 3050 pounds and the final tube frame version at last got down to below 2800 pounds to be ballasted up to race weight.

 

This thread went from on topic, to slightly the same direction these threads go, to now it's all still extremely relevant. I'm loving it!

 

To be fair to my $500 cost I should add the $800. I spent in trailer rental and fuel for a 4000+ mile round trip. Except I also made the trip to pick up some MG parts and spend vacation time with my best friend.

 

here is Nice V12 engine twin turbo, 4 cam direct

injection, ETC.
stock makes 500HP, 750lbs torque, just a slight reprogram of ECU, HP up 800, torque over 1000lbs!
that way dont have to take the engine apart!

 

IVAN you are right ALL this talk and NO action ,is getting old!

 

Well I do know that with 15lbs a 6 liter on pump gas will only probably put out about 600hp, pretty sad. But at least it'll be super torquey and not have to rev up a lot! Maybe with 102 octane and some sharp tuning possibly get to maybe 800hp? If not at least 700hp. But what it comes down to, is this, me doing it. Right now I'm just wrestling with what to do for engine management, either piggyback like a aem, or just rawdogging the eeprom and hopefully someone can find me a definition file or map. https://frsport.com/aem-electronics-...QaAq-AEALw_wcB

 

Use a self learning computer to get close and then under various driving conditions you can get closer. The truth is there is a massive amount of time in the program on modern cars. Idle quality A/C on, off at various temps, various atmospheric conditions etc will consume many many hours and then later be affected by other modifications.
And that’s totally ignoring smog laws and various fuels selected.
My pickup I can burn anything from 87 octane to 100 plus octane. It will read and adjust timing etc accordingly. The fun part is to run normal fuel down to the last few miles and switch to E85. Using regular 87 octane that big heavy 4WD truck is brisk and will out accelerate the Jaguar V12 by an embarrassing amount. But E85 actually smokes the tires.

The point is unless you are willing to do or pay someone else to do the boring development work your numbers are purely theoretical. Newer engines with modern development will beat our beloved V12 ( and cost less doing it)

 

Some engines are easily modified this is not one of them.
V12 twin turbo sounds cool as f&*k but cannot be done on a shoestring budget and would most likely be embarrassed at the red light grand prix.
Everybody here wishes it was different.

 

People think diesel=slow which is false. Even my mostly stock 6.0L f350 can crank out 600hp with free flow intake and a very creative 'race' tune. Mind you the cost is rapid OEM part failures.

Then theres the professionals:

 

Tuning obstacle solved, I will be using stock ecu, I have found support for tuning. I will use a denso definition file which will define most of the maps and then do the rest of the work with the help of very supportive winOLS users. Should I create separate thread for updates on tuning or add here?

 

I think that should be worthy of its own file. I already have my own ECU a Mega Squirt which is familiar to most “tuners” here in the US. The nice thing about mega squirt is it’s self learning so I can get it running once all the sensor inputs are properly connected.

There is a clever trick to gain modern advantages like digital instead of analog inputs. Goes back to when GM was looking at buying Jaguar.
With production machinery dated from WW2 and often purchased 2nd hand the only thing worth while GM saw was the new AJ6 engine. Which GM acquired prior to Ford’s last minute purchase.

GM took it and that formed the bases for the Atlas engine used in their SUV’s like Trail Blazer, Envoy, etc. Since that engine was based on the V12 a lot of parts will work with slight modification.

that’s an easy source for bigger injectors.

 

Seperate thread so it can be sticky'd once finished! Sounds like an opportunity to sell a finished software upgrade after its all said and done?

 

Software? There is no software in most of the Jaguars computers. They are analog not digital. Just resisters, transistors, and Timing circuits. Unless you are handy with a soldering Iron, you have to pull everything and start over.
That’s why it’s so hard.

If you want 500+ horsepower Jag spend about what you’ll spend trying to get that from a V12 and buy an XKR. It will have better handling, brakes, a lot more power and less weight. plus you can stick a key in the ignition and get instant satisfaction.

I love the V12, I’ll build another V12 race car. But I’ll throw a supercharger up on top, weld the carb manifolds together ( turned around) mount a Holley dominator on top. And have some cheap fun.

 

Turbo's... for what? Where are we going? Drag racing.... A Tesla or anything with a warmed-up LS will win and embarrass. Road racing... the Miata will win and embarrass ?

It's the experience. The best upgrade for the XJS by far is a V12 with a 6 speed manual. A modern 6 speed auto might be nice too if one prefers not to pedal and stir. An then... no silencers. The aurally unencumbered V12 is still pleasant, and the extra gears and pedal makes for a unique and great GT experience.

Adding Turbos up's the complexity and decreases the serviceability and reliability drastically.
6 Speed swap does just the opposite.

 

Isn't the problem with new automatics the fact that nobody makes aftermarket ECUs for them?

 

Kind of... but it's solvable. A 0411 early LS PCM can be programmed to control a 4l80e or 4l60e with just an RPM and TPS signal. Same for the 6L80e via an aftermarket solution. Both solutions are about a 1000$ investment for the controller and harness alone...but very doable for the motivated.

It starts to get complicated... becasue you can now get complete but higher mileage LS drop outs with engine, trans harness, pedals for 3 to 5k. Modern LS's are super smooth and powerful. I have driven both a LS with a 6 speed auto and I have in my possession a 6.0L V12 with a 6 speed manual. Both are AMAZING but one is just another LS swap.

 

Complicated is painful. I'd invest in a plug n' play solution with a single solid transmission+brackets+wiring Much like the guy from Finland? Or was it Norway doing a plugin aftermarket V12 ECU for the Jags.

Something like a Ford truck transmission or whatever the mustang has which has usage across the board with ample aftermarket support..doesn't have to be Ford btw.

 

Press X to doubt.

The Atlas doesn’t look anything like the AJ6. Only thing they have in common is that they’re very lazy twin cam straight sixes.

 

More mis-information. Jag ECM's have software starting in 1980. So for Just 3 years, 76 to 79 the all the engine computers were analogue. The VAST majority of ECM have software. From 81 to 1995 the XJS's fueling was digital and based on software. Yes it's hard to get at that software but a soldering iron isnt going to help.