1984 Jaguar XJ6 LS swap (6.0/80E turbo build)
Jaguar XJ6 and XJ129-page write-up
1984 Jaguar XJ6 - 6.0/80E/turbo - LS1TECH - Camaro and Firebird Forum Discussion
Photo: 1984 Jaguar XJ6 - 6.0/80E/turbo - LS1TECH - Camaro and Firebird Forum Discussion1984 Jaguar XJ6 gets an LS 6.0/4L80E turbo swap with E85
The thread author, LQ4-E39, documents pulling the aging Jaguar 4.2 straight six from a rust-free 1984 XJ6 and replacing it with a 6.0 LS and 4L80E recycled from his own Crown Victoria Police Interceptor. The build adds a single turbo, a Holley Terminator X Max standalone, a flex-fuel 20 gallon cell, and a long list of chassis fixes to make the old Jag drivable and durable on boost. The write-up is valuable for its detailed fabrication of mounts, exhaust, fuel and cooling systems and for its running diagnostic log of driveability problems as the car was sorted out.
Specs
As stated in the original write-up.
- Engine
- 6.0 litre iron LS (from a Crown Victoria Police Interceptor), SS2 camshaft and 1218 heads retained, single turbo, non-intercooled initially then intercooled
- Gearbox
- 4L80E automatic, rebuilt by a local specialist
- Turbo
- Cast 7875 turbocharger with black compressor housing, T4 flange, custom hot side piping
- Engine management
- Holley Terminator X Max standalone self-tuning ECU, mounted in glovebox
- Fuel system
- 20 gallon flat-bottom fuel cell with -8AN rollover valve, AEM 400lph external pump, adjustable aftermarket FPR, -6AN feed to stock LS1 rail with 80lb Deka injectors, flex fuel sensor, running E85/pump gas blend
- Rear axle
- Dana 44 IRS, originally 2.88 open, later rebuilt with new 3.54 Dana gears and an Auburn 19-spline Posi limited slip carrier
- Cooling
- 4th Gen LT1 F-body replacement radiator later swapped for a C5 Corvette radiator, LS3 water pump, Motorad 160F thermostat, surge tank from a 2005-2010+ Equinox
- Wheels
- BMW M-Parallel 18x9.5 wheels with 255/35/18 tyres, and alternative 1980s Trans Am GTA mesh 16x8 wheels
- Interior
- Steering wheel replaced with smaller aftermarket wheel and hub adapter; power leather seats from a 1995 XJR fitted
- Instrumentation
- Stock tachometer and speedometer retained, driven via a Dakota Digital SGI-100BT interface from the Terminator X
Parts used
Parts named as used in the original write-up, grouped the way the Parts page groups them. Where one of the shops we index lists the same thing for this car, it is shown underneath with a link to the shop.
Engine 1
- 6.0 litre LS engine
Reused from the builder's Crown Victoria Police Interceptor as the new powerplant
Fuel & Ignition 6
- Holley Terminator X Max
Standalone self-tuning engine management replacing the factory Jaguar PCM
- Cast 7875 turbocharger
Single turbo mounted front passenger side with custom hot side piping
- 80lb Deka fuel injectors
Fitted to a stock LS1 fuel rail for the flex fuel setup
- AEM 50-1005 fuel pump
External 400lph pump feeding the fuel cell system
- Adjustable aftermarket fuel pressure regulator
Replaced a restrictive C5 Corvette FPR to stabilise fuel pressure under boost
In the shops
Fuel Pressure Regulator ↗
Moss Motors – Triumph TR6/TR250· $115.75 USD
Fuel Pressure Regulator ↗Moss Motors – Triumph TR6/TR250· $141.99 USDFuel Pressure Regulator ↗Moss Motors – Triumph TR6/TR250· $178.46 USD - 20 gallon flat-bottom fuel cell
Replaced twin steel factory tanks, strapped into the trunk floor
In the shops
Pro Sport 8 Gallon Fuel Cell ↗Rally Design· £359.35 GBP
Pro Sport 12 Gallon Fuel Cell ↗Pro Sport 16 Gallon Fuel Cell ↗
Cooling 4
- C5 Corvette radiator
Replaced the F-body radiator to eliminate a pressurised radiator cap issue causing coolant loss
In the shops
Radiator Cap - Chevrolet Chevelle/Corvette/El Camino (Motorad) ↗
Belcher's American Auto Parts (UK)· $13.00 USD
Radiator Cap - Chevrolet Corvette/El Camino/K10/K20 (Motorad ST7) ↗Belcher's American Auto Parts (UK)· $13.00 USD - LS3 (2010 Camaro) water pump
Fitted to gain clearance for an air-to-air intercooler installation
In the shopsFuel Pump To Carb Line (1969 Camaro W/427 & Holley Carb) ↗
Collectors Auto Supply - 1969 Camaro· $185.97 USDPre-Bent Steel Fuel Pump to Carb Line for 1969-1972 Camaro Z28 (Holley) ↗Collectors Auto Supply - 1969 Camaro· $183.97 USDStainless Steel Fuel Pump to Carb Line (1969-72 Camaro Z28 & Holley Carb) ↗Collectors Auto Supply - 1969 Camaro· $199.97 USD - Motorad 160F thermostat
Installed to run cooler operating temperatures
- Equinox heater core surge tank
Used as a coolant surge/expansion tank with deaeration benefits
In the shops
Heater Core ↗Moss Motors – Triumph TR6/TR250· $229.99 USDCORE, heater matrix ↗Moss Motors – Triumph TR6/TR250· $149.99 USD
Heater Core to Pipe Hose ↗Moss Motors – Triumph TR6/TR250· $12.00 USD
Gearbox & Drivetrain 4
- 4L80E automatic transmission
Rebuilt by a local specialist using parts from two donor units
In the shops
Automatic Transmission Seals & Filters ↗Moss Motors – Triumph TR6/TR250· $0.00 USD
O-Rings for XJ-40 Automatic Transmission ↗Moss Motors – Triumph TR6/TR250· $10.39 USD
Automatic Transmission Shifter Components ↗Moss Motors – Triumph TR6/TR250· $0.00 USD - Fabricated traction bars
Square bar arms mounted to the differential to control axle wrap and stop driveshaft-tunnel contact
In the shops
1967 Camaro NOS Round Traction Bar Radius Rod ↗Heartbeat City Camaro· 759.95
1967 Camaro Round Traction Bar Radius Rod Assembly ↗
1967 Camaro Square Traction Bar Radius Rod Assembly ↗ - Dana 3.54 ring and pinion gears
Replaced destroyed 2.88 gears after the open diff failed
In the shops
Ring & Pinion Gear Set, 4.55:1 ↗Moss Motors – Triumph TR6/TR250· $515.50 USD
Ring & Pinion Gear Set, 3.54:1 ↗Moss Motors – Triumph TR6/TR250· $841.75 USD
Ring & Pinion Gear Set, 3.07:1 ↗Moss Motors – Triumph TR6/TR250· $485.25 USD - Auburn 546085 limited slip differential
Fitted in place of the factory open carrier for better traction
In the shops
Quaife Limited Slip Differential ↗.png?ts=1732716603)
limora.com· €1,967.27 EURDana Limited Slip Differential (New) ↗limora.com· €4,070.32 EUR
Limited Slip Differential Clutch Pack ↗Moss Motors – Triumph TR6/TR250· $169.25 USD
Suspension & Steering 1
- Poly rack mounts
Replaced worn steering rack bushings to tighten up vague steering feel
Wheels & Tyres 2
- BMW M-Parallel wheels
18x9.5 wheels run with 255/35/18 tyres using adapted lug nuts
- Trans Am GTA mesh wheels
1980s 16x8 Pontiac wheels fitted as an alternative look, requiring ride height changes
In the shops
Rear Wing Spoiler, Fiberglass, 1982-1990 Trans Am GTA ↗
Chicago Muscle Car Parts - 1969 Camaro· $570.00 USD
Interior 1
- Aftermarket smaller steering wheel and hub adapter
Replaced the worn factory wheel, required a sub-harness for the horn
In the shops
Steering Wheel Adapter (9 to 6 Bolt) ↗Moss Motors – Triumph TR6/TR250· $44.99 USD
Jaguar/Land Rover Power Steering Adapter Special Tool NOS ↗
Sports & Classics· $389.95 USD
Moto Lita Flat Riveted Wood Steering Wheel Kit 14" with Hub ↗Betaset (France)· €390.00 EUR
Electrical 1
- Dakota Digital SGI-100BT interface
Used to drive the factory tachometer and speedometer from the Terminator X signals
In the shops
Dakota Digital VFD Gauge System - Ford Truck 1935-37 ↗H&H Classic Parts - Camaro· $815.95 USD
Dakota Digital RTX Gauge System - Ford Truck 1992-96 ↗
Dakota Digital RTX Gauge System - Ford Truck 1997-04 ↗
Photos
357 pictures collected from the write-up, in the order they were posted, shown from 1984 Jaguar XJ6 - 6.0/80E/turbo - LS1TECH - Camaro and Firebird Forum Discussion. A picture opens larger here, with the way through to the page it is on.
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How it was done
Starting condition
The 1984 XJ6 had been owned for over a decade by someone who maintained it carefully but it had stopped running. The builder, already parting with a 6.0/80E driveline from his Crown Vic, saw it as a rust-free candidate that would avoid his usual bodywork headaches.
Engine and transmission swap
The stock 4.2 six and three-speed auto were pulled and a 6.0 LS with freshly rebuilt 4L80E went in, using fabricated engine and transmission mounts, a 302-1 oil pan for clearance, and a modified front accessory drive to clear the bonnet.
Turbo and fuel system
A single cast 7875 turbo was fitted on the passenger side with custom fabricated manifolds, downpipe and hot side piping, later joined by an air-to-air intercooler. The twin factory fuel tanks were abandoned in favour of a 20 gallon fuel cell, external pump, adjustable regulator and flex sensor to run E85 blends.
Chassis and suspension sorting
Ride height, wheel fitment, worn bushings, tie rods, ball joints, and a wandering alignment were worked through over many sessions. A driveshaft-to-tunnel clearance problem under power led to fabricated traction bars tying the differential to the old centre bearing mount.
Driveability and tuning
After first startup on the Terminator X Max, the builder chased idle, exhaust leaks, a coil harness corrosion misfire, cooling system overheating under boost, and gradually raised boost from 8 psi to over 14 psi while monitoring AFR and plug readings.
Running failure and axle rebuild
The original 2.88 open differential failed when a retaining pin let a cross shaft damage the pinion. The axle was rebuilt with reinforced carriers, new Dana 3.54 gears and an Auburn limited-slip unit sourced through two specialist shops.
Interior and cosmetic updates
The builder sourced power leather seats, wheels and a MAF sensor from a wrecked 1995 XJR, wired the seat modules in himself, and fitted a smaller aftermarket steering wheel while getting the factory gauges working through a Dakota Digital interface.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at 1984 Jaguar XJ6 - 6.0/80E/turbo - LS1TECH - Camaro and Firebird Forum Discussion ↗
Worth knowing
- An adjustable boost-referenced fuel pressure regulator is worth using over a restrictive stock-style C5 Corvette unit on any boosted build
- Measuring front toe with the suspension unloaded can hide a large toe-out change once the suspension compresses, so alignment should be checked loaded
- A cracked or galled factory differential should be fully inspected and rebuilt rather than reused after a failure, even if damage looks confined to one area
- Jaguar IRS driveshaft tunnel contact under power is a known issue that needs a traction arm solution tied into a strong chassis point