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Dale Knapke's 1972 TR-6 with 2.3L Ford SVO Turbo-4

Dale Knapke · 1972 Triumph TR-6

Triumph TR6

britishv8.orgBritish V8 Newsletter, Volume XV Issue 2, September 2007 (additional photos July 2013)

Read the full write-up at britishv8.org ↗

Photo: britishv8.org

A 1972 TR6 rebuilt with a turbocharged Ford 2.3L four-cylinder

Dale Knapke replaced his TR6's inline six with a turbocharged and fuel-injected 2.3L Ford SVO four-cylinder, then built a custom four-link rear suspension and drag-strip-capable drivetrain around it. Over decades he kept developing the engine, eventually reaching close to 400 horsepower, and rebuilt the car again after a track-day crash, adding a rollcage and a longer wheelbase. The write-up is worth reading for a first-hand account of a four-cylinder conversion that its builder argues is simpler than a typical V8 swap.

Specs

As the owner states it.

Engine
2.3L (140cid) Ford SVO 4-cylinder from a 1987 Thunderbird Turbo Coupe, turbocharged and fuel injected
Cooling
Custom aluminum radiator and 16 inch electric fan
Exhaust
Stainless steel tubular header, single 3 inch turbo downpipe splitting into dual 2.25 inch tubes into dual mufflers
Transmission
Ford Motorsport Heavy Duty T5 5-speed with 2.95:1 first gear
Clutch
Centerforce stage-3 clutch with McLeod hydraulic throw-out bearing
Rear axle
Ford 9 inch with 3.89:1 ratio, Moser aluminum center section, Moser narrowed axles, Ford Motorsport limited slip differential
Suspension
Front stock with relocated inboard lower A-arm pivot points; owner designed and built 4-link rear suspension with QA1 adjustable coilover shocks
Brakes
Wilwood master cylinder, Wilwood Dynalight 12.18 inch vented front brakes, Ford Turbo Coupe 10.5 inch vented rear brakes
Wheels
Front Enki 16x6 inch, rear Enki 16x8 inch
Tyres
Front 205/55/R16 Firestone Firehawk, rear 255/50/R16 Firestone Firehawk
Body
Mostly stock with a fabricated hood scoop; floor pan over the axle raised 10 inches; rear frame cross brace removed for the 4-link suspension
Interior
Custom tan leather upholstery, custom dashboard, steering wheel, radio console, welded-in roll bar
Electrical
AutoMeter instruments, battery relocated to trunk
Weight
2395 pounds without driver, 47/53 front-to-rear weight distribution
Performance
11.21 second quarter mile at 121 MPH (later improved to 10.76s at 128 MPH); about 400 horsepower at the engine

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 5

Fuel & Ignition 2

  • DFI Gen VII engine management systemAccel

    Controls fuel injection and ignition, replaced earlier system to unlock more power

  • K&N gauze air filterK&N

    Filters intake air feeding the turbocharger, shown on post-rebuild induction system

    In the shops
    Fuel Filter Gauze ↗Angloparts· €25.58 EUR
    Gauze for Bowl Filter ↗Angloparts· €6.56 EUR
    Fuel Pump Gauze Filter (T24) ↗Angloparts· €0.00 EUR

Cooling 3

Gearbox & Drivetrain 5

Suspension & Steering 1

Brakes 3

Wheels & Tyres 4

  • 16x6 inch front wheelsEnki

    Front wheel fitment for the conversion

  • 16x8 inch rear wheelsEnki

    Rear wheel fitment sized for wider rear tyres

  • 205/55/R16 front tyresFirestone Firehawk

    Front tyre fitted to the Enki wheels

    In the shops
    Inner Tube (16 x 205 Tyre) ↗Moss Motors – Triumph TR6/TR250· $24.75 USD
  • 255/50/R16 rear tyresFirestone Firehawk

    Wider rear tyre for traction

Electrical 1

Other 2

Photos

All 30 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.

Dale Knapke's 1972 TR-6 with 2.3L Ford SVO Turbo-4Photo: britishv8.org
2.3L (140cid) Ford SVO 4 cylinder engine from a 1987 Thunderbird Turbo CoupePhoto: britishv8.org
Dynojet report: 396 horsepower and 398 footpounds of torque!Photo: britishv8.org
Intercooler, custom aluminum radiator, and electric cooling fan.Photo: britishv8.org
Battery has been relocated.Photo: britishv8.org
boost! Note the strap that helps keep the intercooler pipe from blowing off.Photo: britishv8.org
Precision Turbo GT30R76 turbocharger.Photo: britishv8.org
Hood scoop feeds into a plenum integral to the hood, which houses a panel air filter.Photo: britishv8.org
Stainless steel header by Precision Turbo.Photo: britishv8.org
turbocharger installation - induction sidePhoto: britishv8.org
Wilwood brake master cylinder.Photo: britishv8.org
Custom TR6 dashboard and radio console.Photo: britishv8.org
Neatly trimmed luggage compartment.Photo: britishv8.org
Ford 9 inch rear axle.Photo: britishv8.org
Supertrapp mufflers.Photo: britishv8.org
Hood scop and painted grille.Photo: britishv8.org
Roll hoop and luggage rack.Photo: britishv8.org
Enki wheels and Firestone Firehawk tires.Photo: britishv8.org
Dale Knapke, autocrossing at British V8 2007.Photo: britishv8.org
Dale Knapke's TR6, in its element.Photo: britishv8.org
Tubular front subframe.Photo: britishv8.org
Plenum.Photo: britishv8.org
Cruise control (left) and MAP sensor (right).Photo: britishv8.org
A blowoff valve vents excess pressure from the compressor side of the turbocharger.Photo: britishv8.org
Fuel injection controlled by an Accel DFI Gen VII engine management system.Photo: britishv8.org
Afco aluminum radiator.Photo: britishv8.org
A pressure activated wastegate diverts excess exhaust gas away from the turbo.Photo: britishv8.org
Precision Turbo GT30R76 turbocharger.Photo: britishv8.org
K&N gauze air filter.Photo: britishv8.org
Donate Now!Photo: britishv8.org

How it was done

Choosing the engine

Dale started with a 2.3L Ford SVO turbo four from a 1987 Thunderbird Turbo Coupe, a factory engine already good for about 200 horsepower, roughly double the stock TR6 six-cylinder. He built on it with an Esslinger aluminum D-port head, an Esslinger hydraulic roller cam, and a Precision Turbo GT30R76 turbocharger, feeding air through a hood scoop and custom intercooler.

Drivetrain

Power goes through a Ford Motorsport Heavy Duty T5 five-speed with a close 2.95:1 first gear, a Centerforce stage-3 clutch, and a McLeod hydraulic throw-out bearing. The rear axle is a narrowed Ford 9 inch with a Moser aluminum center section and limited slip differential, geared at 3.89:1.

Suspension and chassis changes

The front suspension stayed mostly stock apart from relocating the lower A-arm pivot points for better geometry. The bigger job was designing and building a four-link rear suspension with QA1 coilovers, which needed the floor pan over the axle raised 10 inches and a rear frame cross brace removed.

Brakes, wheels and tyres

Stopping power comes from a Wilwood master cylinder with Wilwood Dynalight 12.18 inch vented front brakes and Ford Turbo Coupe 10.5 inch vented rear brakes. The car rides on Enki wheels, 16x6 up front and 16x8 at the rear, wrapped in Firestone Firehawk tyres sized for grip and drag use.

Body, interior and electrical finishing

Bodywork stayed close to stock aside from the owner-fabricated hood scoop feeding the turbo. Inside, Dale fitted custom tan leather trim, a custom dashboard, steering wheel and radio console, a welded-in roll bar, AutoMeter gauges, and relocated the battery to the trunk.

Ongoing development

Dale kept pushing the engine's output over the years, reaching nearly 300 horsepower before switching to an Accel DFI Gen VII engine management system, after which he got to about 400 horsepower. A dyno session later confirmed 396 horsepower and 398 lb-ft of torque, and his quarter mile times improved as the car matured.

Crash and rebuild

During a track day at Indianapolis in 2010, Dale hit spilled coolant and crashed into a concrete wall, destroying the front clip and bending the frame; he was taken to hospital but still made the group dinner that night. He then rebuilt the car extensively, cutting the frame at the firewall to graft in new metal, adding a 10-point Chrome Moly rollcage, and lengthening the wheelbase by 2 inches to meet NHRA's minimum for his racing class.

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

Worth knowing

  • A turbo four-cylinder swap needs fewer chassis modifications than a typical V8 conversion, so ground clearance can stay low.
  • The stock Ford Turbo Coupe engine management and wiring harness are good starting points and can handle a lot of tuning before becoming a limiting factor.
  • A V8-spec T5 gearbox needs a special pilot bearing when paired with the 2.3L engine.
  • The four-link rear suspension was the hardest part of the build and is only necessary if wide drag tyres or serious traction are wanted; a stock rear end or TR250 leaf springs would simplify things.
  • Track driving carries real risk: a patch of spilled coolant caused a wall impact that destroyed the front clip and bent the frame, leading to a full rebuild with a proper rollcage.

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