Facts and figures from Wiki. The XJR15 is up about 40% on hp and 25% on tq over the XJS 6L.

Did the XJR15 use HE heads and were they special castings? What about the cams, intake manifold and exhaust? I’m just wondering how Jag tuned up the XJR15.

Thanks.


XJR15 1993

Engine type: 60° V12 overhead cam, naturally aspirated
Construction: aluminium-alloy block and heads, forged-alloy pistons, nitrided forged EN40B steel crankshaft with Holset harmonic damper, seven main bearings, cast-iron ‘wet’ cylinder liners, Cosworth pistons
Valve Gear: two valves per cylinder operated by single chain-driven overhead camshaft per bank of cylinders
Fuel System: Zytek electronic engine management
Displacement: 5993 cc/ 365.7 in³
Compression ratio: 11.0:1
Max Power: 335.6 kW/ 450.0 bhp @ 6250 rpm
Specific output: 75.09 bhp (56 kW; 76 PS) per litre
Max Torque: 420 lb·ft (570 N·m) @ 4500 rpm

6.0 HE

The engine was stroked to 78.5 mm (3.1 in) in 1992 for a displacement of 6.0 L (5993 cc)(365.7 ci) to make this one of the most powerful Jaguar production engines to date at 318 hp (237 kW) and 336 ft·lb (456 N·m) at 3750rpm. The 6.0-litre engine on X305 used a new Nippondenso distributorless crank-fired ignition system with coil packs very similar to Ford EDIS-6 units. The last Jaguar V12 engine was produced on April 17, 1997.

 

I have been told that the XJR15 uses standard 6.0L heads post #149 in this tread.

https://www.jaguarforums.com/forum/x...e8/#post807941

 

Although the Jaguar Sport XJR-S 6.0 with the Zytec injection has different part numbers for the head and valves than the regular 6.0. I have no idea what the differences might be (if any).

 

longy; at this time the best heads available for a Jag V12 , are from Austrailia , there is a guy on JF that has some!?

with your time and computer experience,keep at it and you'll find him.

but also there is another place in UK that has some 4 valve twin cam heads , now that will burn your wallet!!

 

The 4 valve heads have been around a long time. Basically they use the heads from two six cylinders, cut up and swapped around to work.
The problem is lack of compression. Supercharging has been used to effectively increase the effective compression