Build catalogue
Calvin Grannis' 1974 TR6 LS1 V8 conversion
britishv8.orgas published in BritishV8 Magazine, Volume XX Issue 1, July 2012
Photo: britishv8.orgA 1974 Triumph TR6 rebuilt around a Chevrolet LS1 V8 and T56 six-speed
Calvin Grannis, a longtime Triumph enthusiast, replaced his TR6's six-cylinder with a 2002 Camaro Z28 LS1 V8 and T56 six-speed gearbox, then reworked the chassis, suspension, brakes, fuel system, wiring and interior to match. The result looks nearly stock from the outside but makes around 408 rear-wheel horsepower, and the write-up is worth reading for how thoroughly every subsystem was upgraded in balance rather than just the engine swap.
Specs
As the owner states it.
- Engine
- 2002 Chevrolet LS1 5.7L V8 (346ci), aluminum block and heads, EFI, coil-on-plug ignition, six-bolt mains, TSP/PRC LS6-style CNC-ported heads, 10.8:1 compression, TSP Comp Cams camshaft (228 duration, 0.588 lift), LS7 lifters, FAST 90mm intake hand-ported by Tony Mamo, Nick Williams 90mm throttle body
- Gearbox
- Tremec T56 6-speed from 2002 Camaro Z28, F-body gearing, Fidanza 12.5lb aluminum flywheel, SPEC Stage 2+ clutch
- Rear axle
- Nissan Infiniti Q45 (R200) viscous limited-slip differential, 3.54:1 final drive, Good Parts CV axles and uprated hubs
- Front suspension
- Quick ratio steering rack, Woodward Precision Power Steering U-joints, Uncle Jack's uprated spindles, Good Parts lowering springs, Spax adjustable shocks, Nylatron bushings, Good Parts anti-sway bar
- Rear suspension
- Good Parts 600lb/inch lowering springs, Roadster Factory coilover conversion with AVO shocks, Good Parts adjustable anti-sway bar (relocated), Good Parts adjustable trailing arm brackets and Nylatron bushings, upgraded trailing arm studs with Helicoil inserts
- Brakes
- Wilwood 1.125in tandem master cylinder and proportioning valve; front Wilwood 4-pot calipers with 12.19in rotors and custom aluminum hats; rear 1997 Nissan Maxima calipers on Don Watson brackets with 1992 Nissan 240SX rotors and e-brake cables
- Wheels
- Rota RB Hyper Black aluminum, 17x7.5, 4-100mm lug spacing, +45mm offset, with one inch spacers/adapters
- Tyres
- Yokohama S-drive W-rated 245/45R17
- Body
- No exterior sheetmetal modifications
- Paint
- PPG Atlantic Pearl Blue two stage paint with white pearl ghost stripes
- Interior
- Custom Kewazinga African rosewood dashboard by Randy Keller/Prestige Autowood, AutoMeter Phantom II digital gauges (set of 7), leather-wrapped Moto-Lita steering wheel, early Mazda Miata seats with headrest speakers and seat heaters, SPAL power windows, Vintage Air Mini Air/Heat/Defrost with Sanden 508 compressor, LED footbox lighting, wool carpet
- Electrical
- Advance Auto-Wire wiring harness, Stinger distribution block and main fuse, Odyssey Extreme Racing ER40 battery in trunk, 140 amp Delco style alternator, LED rear running and brake lights
- Cooling
- Griffin aluminum crossflow radiator (24x19x3in, 2-row 1.25in tube core), 16in 2250cfm electric fan with shroud
- Exhaust
- Hooker Super Competition four-into-one headers (1.625in primaries), 2.5in pipes, Magnaflow X-pipe, dual 2.5in Borla Pro XS mufflers, Monza 2.5-to-4in glass-pack tips
- Fuel system
- Racers Choice 19 gallon aluminum fuel tank, Aeromotive inline fuel pump, Corvette fuel filter/regulator
- Performance
- About 408hp at wheels (5800-6100rpm), about 390ft-lbs at wheels (4500-5200rpm), 0-60 in about 3.5s, 28mpg highway/25mpg city
- Completed
- Road-worthy April 2011; first engine start June 17, 2009
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.
Shop suggestions are being prepared. The owner's parts list is available below.
Engine 8
- Chevrolet LS1 5.7L V8 (346ci)Chevrolet
Base engine from a 2002 Camaro Z28, aluminum block/heads, EFI, coil-on-plug ignition
- LS6-style CNC-ported cylinder heads, 62cc chambers, oversized valvesTexas Speed & Performance / Precision Race Components
Increased flow and compression to 10.8:1
- Comp Cams camshaft (228 duration, 0.588in lift)Comp Cams / TSP
Sourced through TSP for improved power band
- LS7 lifters
Fitted with the upgraded valvetrain
- Chromaloy push rodsChromaloy
Used with the new valvetrain setup
- LS2 timing chain and gears
Fitted during engine build
- Ported LS6 oil pump
Upgraded oiling for the engine build
- Street & Performance Front Runner accessory drive systemStreet & Performance
Provided serpentine belt drive for accessories
Fuel & Ignition 6
- FAST 90mm intake manifoldTony Mamo / AFR
Hand ported for improved airflow
- 90mm throttle bodyNick Williams
Matched to the FAST intake
- K&N gauze air filterK&N
Fitted to the intake system
- Stock 28# fuel injectors
Retained for initial tune
- Aeromotive inline fuel pumpAeromotive
Feeds the EFI system
- Corvette fuel filter/regulatorChevrolet Corvette (donor part)
Regulates fuel pressure to the injectors
Cooling 2
- Griffin aluminum crossflow radiatorGriffin
24x19x3in, 2-row core, upgraded cooling capacity
- 16in electric fan and shroud
2250cfm fan matched to radiator
Gearbox & Drivetrain 7
- Tremec T56 6-speed gearboxTremec
Sourced from the donor Camaro, F-body gearing
- Fidanza aluminum flywheelFidanza
12.5lb flywheel with changeable clutch surface
- SPEC Stage 2+ clutch and pressure plateSPEC
Matched to the flywheel for the LS1/T56 combo
- Aluminum propshaft, shortened to 25inChevrolet
From a Camaro, adapted with mixed U-joints
- Gear shifter relocatorStreet & Performance Inc.
Repositioned shifter to suit the TR6 chassis
- Nissan Infiniti Q45 (R200) viscous limited-slip differentialNissan
Provides 3.54:1 final drive
- Good Parts CV joint axles and uprated hubsGood Parts
Matched to the Nissan differential swap
Suspension & Steering 10
- Quick ratio steering rack
Improved steering response
- Woodward Precision Power Steering universal jointsWoodward Precision Power Steering
Used in the steering column setup
- Uncle Jack's uprated spindlesUncle Jack's
Strengthened front suspension
- Good Parts lowering springs (front)Good Parts
Lowered ride height at the front
- Spax adjustable shock absorbersSpax
Fitted at the front
- Good Parts front anti-sway barGood Parts
Improved front roll stiffness
- Good Parts 600lb/inch rear lowering springsGood Parts
Used with the rear coilover conversion
- Roadster Factory coilover conversion kit with AVO shocksRoadster Factory / AVO
Converted rear suspension to coilovers
- Good Parts adjustable rear anti-sway barGood Parts
Relocated rearward for better geometry
- Good Parts adjustable trailing arm attachment bracketsGood Parts
Fitted with Nylatron bushings
Brakes 4
- Wilwood 1.125in tandem master cylinderWilwood
Paired with a proportioning valve on the rear circuit
- Wilwood 4-pot front calipersWilwood
Fitted with 12.19in rotors and custom aluminum hats
- 1997 Nissan Maxima rear calipersDon Watson
Mounted on custom brackets
- 1992 Nissan 240SX rear rotors and e-brake cablesNissan
Used for the rear brake conversion
Wheels & Tyres 2
- Rota RB Hyper Black wheelsRota
17x7.5in, 4-100mm lug spacing, +45mm offset
- Yokohama S-drive tyresYokohama
245/45R17 W-rated tyres
Body & Trim 1
- PPG Atlantic Pearl Blue two stage paintPPG
Applied with white pearl ghost stripes
Interior 8
- Ford Mustang shifter knobFord
Reamed out to fit the relocated shifter
- Custom rosewood dashboardRandy Keller / Prestige Autowood
Made from Kewazinga African rosewood
- AutoMeter Phantom II digital gaugesAutoMeter
Set of seven gauges for the custom dash
- Moto-Lita steering wheelMoto-Lita
Leather wrapped wheel fitted to the interior
- Mazda Miata seatsMazda
Early-style seats fitted with headrest speakers and heaters
- SPAL power window systemSPAL
Installed with four-pin contact strips at door jambs
- Vintage Air Mini Air/Heat/Defrost systemVintage Air
Climate control with Sanden 508 compressor
- Lizard Skin sound and heat control coatingLizard Skin
Applied for noise and heat insulation
Electrical 5
- Advance Auto-Wire wiring harnessAdvance Auto-Wire
Complete rewire for the V8 conversion
- Stinger distribution block and main fuseStinger
Central electrical distribution point
- Odyssey Extreme Racing batteryOdyssey
Nine pound ER40 battery relocated to the trunk
- 140 amp Delco style alternatorDelco
Polished finish, upgraded charging capacity
- LED rear running and brake lights
Updated rear lighting
Other 5
- Hooker Super Competition headersHooker
Four-into-one design with 1.625in primaries
- Magnaflow X-pipeMagnaflow
Mounted inside the frame for exhaust routing
- Borla Pro XS mufflersBorla
Dual 2.5in mufflers for exhaust note and flow
- Monza glass-pack exhaust tipsMonza
2.5in-to-4in tips visible under the tail
- Racers Choice aluminum fuel tankRacers Choice Inc.
19 gallon fabricated tank replacing stock unit
Photos
All 40 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.
How it was done
A lifelong Triumph enthusiast
Calvin Grannis' interest in British sports cars began in the late 1970s with a 1968 TR250, which he modified with balanced internals, a shaved head and triple Webers. Years later he found the BritishV8 website and message board, which inspired him to build a second Triumph, one that kept the same spirit of fun but aimed for modern standards of smoothness, comfort and confidence.
Choosing the powertrain
Calvin settled on a 2002 Chevrolet Camaro Z28 LS1 V8 paired with its factory T56 six-speed manual gearbox. The LS1 came with an aluminum block and heads, electronic fuel injection, coil-on-plug ignition and six-bolt main bearing caps, giving a strong, modern base to build power and reliability around.
Building the engine
The LS1 was fitted with Texas Speed & Performance/Precision Race Components LS6-style CNC-ported heads with oversized valves, a TSP-sourced Comp Cams camshaft, LS7 lifters and an LS2 timing chain. Induction came from a hand-ported FAST 90mm intake and Nick Williams throttle body, tuned through the stock PCM using HP Tuners software.
Drivetrain and rear end
Power runs through a Fidanza flywheel and SPEC Stage 2+ clutch to the T56 gearbox, then down a shortened Camaro aluminum propshaft to a Nissan Infiniti Q45 viscous limited-slip differential, chosen for its 3.54:1 ratio, fitted with Good Parts CV axles and uprated hubs.
Chassis, suspension and brakes
The frame was reinforced at the front suspension mounts, transmission crossmember and rear suspension towers to cope with the extra power. Good Parts supplied lowering springs, anti-sway bars and adjustable trailing arm brackets front and rear, while Wilwood supplied the front brake calipers and master cylinder, with Nissan-sourced rear calipers and rotors.
Fuel, cooling and electrical systems
A Racers Choice 19 gallon aluminum fuel tank feeds the engine through an Aeromotive inline pump and a Corvette filter/regulator. Cooling comes from a Griffin aluminum radiator and electric fan. The car was rewired with an Advance Auto-Wire harness, a Stinger distribution block, and a trunk-mounted Odyssey racing battery.
Interior and finishing touches
Inside, Calvin fitted a custom rosewood dashboard, AutoMeter digital gauges, a leather Moto-Lita wheel, modified Miata seats with heaters and headrest speakers, power windows, and a Vintage Air climate system. The exterior received subtle ghost stripes over PPG Atlantic Pearl Blue paint, keeping the bodywork visually stock.
On the road
The TR6 was declared road-worthy in April 2011, after first starting the engine in June 2009. At the wheels it produces about 408 horsepower and 390ft-lbs of torque, reaching 60mph in roughly 3.5 seconds while still returning 28mpg on the highway. Calvin and Brenda drove it 2000 miles round-trip to the BritishV8 2012 meet.
A summary in our own words. The full account, with all its detail, is the owner's: read it at britishv8.org ↗
Worth knowing
- Balancing every subsystem, not just the engine swap, keeps a V8 conversion feeling coherent rather than excessive.
- Reinforcing the chassis at suspension and transmission mount points is worthwhile before putting big power through an old frame.
- Sourcing driveline parts from unrelated donor cars, like the Nissan differential and brakes, can solve fitment and cost problems.
- Keeping the exterior visually stock lets the performance be the surprise rather than the styling.
- Using stock injectors initially left room to revisit fuelling later as the tune matured.