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Kingsley Dunstan's 1977 Triumph Stag LS1 V8 conversion

Kingsley Dunstan · 1977 Triumph Stag

Triumph Stag

britishv8.orgas published in BritishV8 Magazine, Volume XX Issue 1, July 2012

Read the full write-up at britishv8.org ↗

Photo: britishv8.org

A 1977 Triumph Stag rebuilt with a Chevrolet LS1 V8

Kingsley Dunstan replaced the Stag's original engine with a fuel-injected Chevrolet LS1 5.7L, paired to an upgraded TH700R4 automatic and a BMW-sourced rear end. The write-up is a detailed specification sheet covering custom cooling, exhaust, brakes, suspension and instrumentation work done with help from Ray Ferrari and Bruce Pollock, useful for anyone planning a similar LS-swap into a British classic.

Specs

As the owner states it.

Engine
Chevrolet LS1 5.7L with electronic fuel injection, stock intake manifold, plenum, and throttle body, reprogrammed PCM for MAFless tuning, K&N air filter, Aeromotive adjustable fuel pressure regulator, Moroso reverse-pickup aluminum oil sump, remote-mounted oil filter
Cooling
Custom PWR aluminum radiator, 16 inch Zirgo thermostatically controlled fan
Exhaust
Custom four-into-one headers, dual MagnaFlow dual-outlet stainless mufflers, four rear outlet 2.5 inch system
Transmission
Upgraded Turbo 700 (TH700R4) 4-speed automatic with B&M deep sump, 2800rpm stall converter, B&M Mega Shifter
Rear End
BMW 8 bolt with limited slip differential, 3.7:1 ring and pinion, Datsun drive shafts
Front Suspension
Stock except for KONI shock absorbers
Rear Suspension
Stock except for KONI shock absorbers, up-rated springs, and polyurethane bushings
Brakes
Master: Nissan Skyline 15/16 inch bore with modified rear brake bias valve. Front: Nissan Skyline R32 4-pot aluminum calipers, 280mm rotors. Rear: Nissan S14 Silvia calipers with modified handbrake actuators
Wheels/Tires
Modified hubs, TIG 17x7 aluminum wheels, Maxxis MA-V1 P205/45R17 tires
Instruments
Speedhut Legacy white dial voltmeter, coolant temperature, oil pressure, fuel level, GPS speedometer, and tachometer gauges, plus shift light
Interior
Mostly stock, with Alpine stereo system
Completed
March 2010, but still not yet finished

Parts used

What the owner names in the 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 4

Fuel & Ignition 1

Cooling 2

Gearbox & Drivetrain 6

Suspension & Steering 1

Brakes 3

Wheels & Tyres 2

  • 17x7 aluminum wheelsTIG

    Fitted on modified hubs

  • MA-V1 P205/45R17 tiresMaxxis

    Tires fitted to the TIG wheels

Interior 1

  • Stereo systemAlpine

    Added to the mostly stock interior

Electrical 1

  • Legacy white dial gauge setSpeedhut

    Instrument cluster covering volts, coolant temp, oil pressure, fuel, GPS speed, tach, and shift light

    In the shops
    DIAL KIT DASH MINI WHITE ↗Motaclan Limited· £26.46 GBP

Other 2

  • Four-into-one headers

    Custom fabricated exhaust headers for the V8

  • Dual-outlet stainless mufflersMagnaFlow

    Stainless mufflers feeding a four-outlet 2.5 inch exhaust

Photos

All 16 pictures in the write-up, in the order they were posted, shown from britishv8.org. A picture opens larger here, with the way through to the page it is on.

Kingsley Dunstan's Chevy LS1 5.7L V8 powered 1977 Triumph StagPhoto: britishv8.org
Chevrolet LS1 5.7L with electronic fuel injection. Stock intake manifold, plenum, and throttle body.Photo: britishv8.org
Moroso reverse-pickup fabricated aluminum oil sump.Photo: britishv8.org
MAFless fuel injection.Photo: britishv8.org
Aeromotive adjustable fuel pressure regulator.Photo: britishv8.org
Upgraded Turbo 700 (TH700R4) 4-speed automatic, with B&M deep sump.Photo: britishv8.org
BMW 8 bolt with limited slip differential, 3.7:1 ring and pinion, and Datsun drive shafts.Photo: britishv8.org
B&M Mega Shifter.Photo: britishv8.org
Speedhut Legacy white dial instruments.Photo: britishv8.org
Mostly stock interior, but with Alpine stereo system.Photo: britishv8.org
Triumph Stag's came with a distinctive T-bar rollover structure.Photo: britishv8.org
Venom8Photo: britishv8.org
Kingsley Dunstan's Triumph Stag is only slightly lowered from stock.Photo: britishv8.org
Maxxis MA-V1 P205/45R17 tires.Photo: britishv8.org
Four rear outlet 2.5 inch exhaust system.Photo: britishv8.org
Donate Now!Photo: britishv8.org

How it was done

The swap

Kingsley Dunstan, working with Ray Ferrari and Bruce Pollock, fitted a Chevrolet LS1 5.7L fuel-injected V8 into his 1977 Triumph Stag, keeping the stock intake manifold, plenum, and throttle body. The engine control unit was reprogrammed for MAFless tuning, estimating airflow from manifold pressure, engine speed, and throttle position rather than a mass airflow sensor.

Oiling and fuel system

A Moroso reverse-pickup fabricated aluminum oil sump was fitted to suit the car's layout, along with a remote-mounted oil filter. Fuel pressure is managed with an Aeromotive adjustable regulator, and a K&N air filter handles intake.

Cooling and exhaust

A custom PWR aluminum radiator and a thermostatically controlled 16 inch Zirgo fan were installed to manage the V8's heat. Custom four-into-one headers feed dual MagnaFlow stainless mufflers, exiting through a four-outlet 2.5 inch system.

Transmission and driveline

The V8 drives through an upgraded Turbo 700 (TH700R4) four-speed automatic fitted with a B&M deep sump, a 2800rpm stall converter, and a B&M Mega Shifter. Power reaches a BMW 8-bolt limited-slip differential with a 3.7:1 ring and pinion, connected by Datsun drive shafts.

Suspension and brakes

Front suspension stayed largely stock apart from KONI shocks, while the rear kept its stock layout but gained KONI shocks, up-rated springs, and polyurethane bushings. Braking was upgraded using a Nissan Skyline master cylinder, Nissan Skyline R32 four-pot front calipers with 280mm rotors, and Nissan S14 Silvia rear calipers with modified handbrake actuators.

Wheels, instruments and interior

Modified hubs carry 17x7 TIG aluminum wheels shod with Maxxis MA-V1 tires. Speedhut Legacy white dial gauges track voltage, coolant temperature, oil pressure, fuel level, GPS speed, and revs, with a shift light. The interior remains mostly stock, upgraded only with an Alpine stereo system.

A summary in our own words. The full account, with all its detail, is the owner's: read it at britishv8.org ↗

Worth knowing

  • Fitting a reverse-pickup sump helps solve oil pan clearance issues in tight V8 swaps.
  • Reprogramming the PCM for MAFless tuning avoids relocating a mass airflow sensor.
  • Sourcing brake components from Nissan Skyline and Silvia parts bins can upgrade stopping power affordably.
  • Using a BMW differential with Datsun drive shafts allows a workable rear-end solution without custom axles.
  • Custom fabrication of mounts, cooling, and exhaust is unavoidable and should be planned for from the start.

britishv8.org

Read in full on 5 September 2026. The work, the words and the pictures are Kingsley Dunstan’s; this page is a catalogue of them in our own words, and a signpost.

Read the full write-up at britishv8.org ↗

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