I just got my AJ6 engineering goodies last night and excited to start up my xjs for the first time.

How much horsepower and torque do you think my xjs has:

1990 XJ-S V12 USA spec

6.0 V12 from 94 US spec XJ12
4l80e 4 speed trans from 94 xj12 (will be running the TCI EZ-TCU
Aj6 engineering TT exhaust with silencer substitute pipes
AJ6 engineering Super Enhanced CU16 ECU modified for 6.0 and TT exhaust
Swain Tech coated and ported exhaust manifolds (did not cut open)
Air Injection Pump deleted
Dual Electric Fans

I also have the FasterJags Growler Air Intakes but haven't decided yet if I want to run those or use the stock with a K&N filter.

I am thinking 304hp stock for 6.0 plus 35 for TT exhaust plus 10 for exhaust manifold (Alan Scott mod) + 10 for air injection and dual electric fans. This would be 360hp total at the crank. If I use the Growler intake 10hp more for 370hp...

What do y'all think?

 

I think like most people in the car world you're giving way too generous figures to the HP gains of each item. Not trying to be mean but all told with each of those mods your looking at a realistic probability of 15 to 20 total over stock. Most claim 10hp with an air cleaner change when the real figure is more like 2 to 3.

 

In most cases, such mods are designed to work together and are not cumulative. E.g., opening up the intake might help the exhaust reach its max number.

Nevertheless, sounds like a great build. I look forward to more updates as you get it dialed in.

Padre

 

My feeling is not so much the numbers but how does it FEEL, should give you plenty more in the "grunt/grin" dept!

 

From a previous life I know that the cooling fans for a large industrial engine running under continuous full load producing 4500 hp used 13hp. It was 3 fans, 48" each. So there is no way the tiny fan in an XJS will use 10hp.

My guess is your mods will give 10-15hp at most.

 

From the work TWR did for Jaguar on a road going 6.1L HE. This development ended up powering the TWR road going XJS, and later Jaguar implemented the 6.0L in all XJS models

GRPA exhaust manifolds 2" down pipes and open exhaust
TWR (road car) intakes with K&N filters.

370hp at 5200rpm, with stock TB's.

The stock TB's flow 650cfm each so more than big enough to support 500hp.

I would think 350-360 with a CAI and good exhaust and down pipes. The V12 exhaust and intake are VERY restrictive in order to keep noise levels at Jaguar levels.

TWR also tested the GRPA inlet manifold on this 6.1L engine, interestingly the engine made 3% less HP under 5000rpm but peaked just under 400hp at about 6000rpm

 

of course the best way is dyno the car and get a rear wheel HP number, before and after!

my car did not run when i got it, basket case all apart.

but i have had it dynod after the rebuild, back in the early 2000s,

best run ever was only 325 WHP, lot of guessing what crank HP might be, but no matter its whats at the wheels that count!

i can make a list, hope to remember what i had done 21 years ago 1994/95, actually quite a bit!

truthfully(like most people) i was never completly satisfied, i have modfied many engines and darn old USA V8s respond the easiest to making torque and HP.

TWR made a lot of mods(read expensive) to make the final 500HP, all above any normal road speeds,( like Warrjon said).

few people drive around at 5500/ 7000 rpm.

but i built my car long before the TWR book was printed.

i think the best thing to do to a Jag V12 is increase the stroke to as much as you can afford money wise, and get all the torque you can.

 

of course the best way is dyno the car and get a rear wheel HP number, before and after!

my car did not run when i got it, basket case all apart.

but i have had it dynod after the rebuild, back in the early 2000s,

best run ever was only 325 WHP, lot of guessing what crank HP might be, but no matter its whats at the wheels that count!

i can make a list, hope to remember what i had done 21 years ago 1994/95, actually quite a bit!

truthfully(like most people) i was never completly satisfied, i have modfied many engines and darn old USA V8s respond the easiest to making torque and HP.

TWR made a lot of mods(read expensive) to make the final 500HP, all above any normal road speeds,( like Warrjon said).

few people drive around at 5500/ 7000 rpm.

but i built my car long before the TWR book was printed.

i think the best thing to do to a Jag V12 is increase the stroke to as much as you can afford money wise, and get all the torque you can.

i make my torque thru gearing mods, trying to make use of the high RPM potential!

 

Forgot to mention the limit for the OEM HE heads is about 400 hp due to the valve shrouding.

 

What is has an ignition system? Is Marelli or Lucas?
If Lucas, it is difficult to connect the TCI EZ-TCU.
If Marelli, I will write how to set up for a smooth gear change

 

You are at the perfect crossroads to get your car dyno tested now; and then again when you are complete.

You'll have real world data that can clear up all of the hype surrounding these types of upgrades!

 

I am running the stock 90 Marelli system. Rodger modified the '90 ECU fueling to work with the 6.0.

I would greatly appreciate the write up.

Thanks!!
-Scott

 

Sorry Vee but I didn't dyno it in the xj12 before it was removed. I am going straight from a overheated 5.3 with no compression to the 6.0 with the mods in the xjs.

I could do a dyno with and without the growlers....

 

LOCATE a DYNO....


I do find it funny while talking to these guys (not naming companies or products) about buying this or that and they say so much of a performance gain... and I reply "GREAT there is a chassis Dyno right around the Block from about a mile and a half down the road, 3 pulls for 100 dollars! I can do a before and after...


they seem to really get off the phone with me QUICK!

 

It's a 94 6.0L it'll most likely be Marelli, not sure when Jaguar went EDIS coil packs but I think it was later than 94.

 

Yes, larger TB butterflys in a TB that is already capable of flowing 600cfm each..............

 

They went EDIS on the 1995-7 XJ12 sedans, never on the XJS.

 

My motor has a distributor. No coil packs.

 

This is a 90 XJS with 6.0L that has been transplanted from an XJ12.

I'll be Marelli then....

Have a look at what TWR did during their R&D of the 6.1L.

Stock 6.1L made 340hp at 5200. This is with ALL 5.3L inlets exhaust etc.

Cold air intakes K&N filters and larger trumpets on stock manifolds and TB's
GRPA exhaust manifolds and downpipes no mufflers.

Made 380hp @ 5200rpm

Add GTPA large manifolds and lost 3% power under 4000rpm and made an additional 15hp at 6000rpm

70mm TB's made less than 5hp over 5500rpm.

 

.


warrjon , that must be Crankshaft HP , NOT WHP??