Supercharged!: Installing the New Moss Triumph TR6 Supercharger System

Regular British Motoring readers know that over that last few years, Moss Motors has been at the forefront of a new trend: retrofitting British classics with upgraded performance and technology. Modern overdrive transmissions, tubeshock conversions, electronic fuel injection systems, and a variety of supercharger kits have reinvigorated and revolutionized the sports car hobby. Classic car owners are beginning to realize subtle yet tasteful modifications don’t detract from a car’s value, and the exponential increase in comfort, driveability, and fun-factor improve the overall experience of owning one of these rolling time machines.

The latest marvel in high-performance engineering to come out of the Moss R&D shop is also one of the most impressive: an all-new Supercharger kit for the Triumph TR6. Triumph’s inline-six powerplant offers impressive torque and mid-range power when compared to four-cylinder MGs and other performance cars of the day, but true petrolheads know that there’s no such thing as too much horsepower. Rather than slapping a modified existing kit onto a big Triumph six, however, Moss spent the better part of a year fine-tuning their design to achieve the perfect balance of power, usability, and vintage style.

Expanding upon knowledge they had gained with the successful MG-T, Spridget, and MGB supercharger systems, Moss engineers decided to use an Eaton positive-displacement Roots-type supercharger once again. The Eaton supercharger design has proven itself on several late-model OE applications, including R-type Jags and the Ford Lightening super truck. While the MGB kit relied upon an Eaton M45 supercharger, the larger-displacement TR6 mill requires more airflow. The impressive-looking Eaton M62 blower was selected for the job. Then Moss engineers were left with the daunting task of making it work, fit, and look right in one sportscardom’s most iconic engine compartments.

The first obstacle that had to be dealt with was a change in cylinder head port design that occurred in 1972. Since Moss engineers utilize computerized modeling software to design 3D renderings of the supercharger intake manifold before real-world prototypes were constructed, they decided to build two separate kits with different intakes: one for 1968 TR250 through 1972 TR6, and one for the 1973-76 TR6.

Once the intake manifold designs were finalized, the rest of the kit needed to be fleshed out. A single Holley 350cfm two-barrel carburetor was selected for its excellent performance and simple tuning characteristics. Accessory brackets, drive pulleys, and a new throttle cabin system round out the package.

The first production supercharger system has already been installed and dyno tested, turning out 118.5 rear wheel horsepower at 4900 rpm. That’s an impressive gain over the stock late TR6 typical 75-80 rear wheel horsepower. As of this writing, pricing for the kit has been set at $3,495. Considering the combined cost of standard Triumph performance enhancements (Weber carburetors, header, tuned exhaust), and the fact that the supercharger system will make more power than any other single enhancement available for the TR6, the system is a bargain. Best of all, with an Eaton supercharger tucked under the bonnet, your Triumph will actually go as fast as it looks!

  1. The original air filter box is removed and set aside.
  2. All of the vacuum and fuel lines have to be carefully removed and labeled. The instructions cover most hose routing details.
  3. The front manifold heating hose is disconnected.
  4. Lower manifold retaining nuts must be removed, taking care not to drop the manifold retaining clamps. Next, the upper manifold retaining nuts are removed, then the intake manifold and carburetors lift away from the engine.
  5. The exhaust manifold can be removed and all remnants of gasket material must be carefully cleaned from the head.
  6. Both the radiator cowl and radiator are removed from the car allowing access to the front of the engine. Here the water pump is being removed, so that a new unit designed to accept the 4 rib belt pulley can be installed
  7. The steering rack has to be loosened to allow removal of the original front crank pulley assembly.
  8. Here the kit components are laid out, so they can be easily identified.
  9. The carburetor is bolted to the adapter plate, and then assembled on the supercharger.
  10. The automatic belt tensioner removes slack from the supercharger drive belt and decreases boost lag.
  11. After temporarily removing the steering rack for clearance, mount the belt tensioner to the front of the engine. Next install the ribbed crank pulley and original hub spacer.
  12. The original alternator pulley must be carefully removed. This can be done on the car if you have access to an impact wrench. Otherwise, it’s a good idea to remove the alternator and have the pulley removed and replaced with the new ribbed pulley by a shop.
  13. Here you can see the new water pump installed.
  14. Next to be installed is the new throttle linkage support panel.
  15. The new throttle cable connects to the support and is bolted to the throttle bell crank.
  16. Now the exhaust manifold can be reinstalled on the new Moss-supplied stock gasket.
  17. Then the supercharger assembly is installed giving us an inkling of how awesome the engine bay is going to look.
  18. The original clamps are used to mount the new supercharger intake manifold. All the mounting nuts must be tightened to the correct torque.
  19. Now, we can hook up the accelerator cable to the carburetor.
  20. With the supercharger installed, you can see the front support components that prevent flex when the engine revs. The support cradle is installed on the nose of the supercharger.
  21. The new four-rib belt takes a bit of fiddling to get behind the rack, but is easier to fit than the original belt. What’s more, the automatic tensioner assembly makes it easy to fit the belt and maintain correction tension.
  22. A new heater hose assembly is installed and held in place by supplied clips and brackets.
  23. The new vent line connects from the valve cover tot he carburetor, which eliminates crankcase pressure.
  24. The newly supercharged TR6 will look as impressive as it drives. Power has been increased significantly, and the car drives like a completely different vehicle.

'Supercharged!: Installing the New Moss Triumph TR6 Supercharger System' have 6 comments

  1. December 28, 2016 @ 9:43 am Danny Fisk

    Why was the supercharger kit for the TR6 discontinued?


    • January 12, 2017 @ 9:09 am stuursmad

      Danny, The TR6 supercharger system has been discontinued because we couldn’t get the carburetors any longer. We would have had to change to another carburetor. Unfortunately we couldn’t justify the tooling of the new carb to supercharger manifold, the tuning involved to get it all right again and worst of all the only carbs that we could find that we would consider acceptable finished too close to the firewall to allow a turn to a new air filter. That meant perhaps a new shorter supercharger nose to move it further forward, all custom. With so many things stacked up against it we finally had to give up and let it go.


      • February 3, 2017 @ 10:23 am John Jervis

        Are there any inlet manifolds left without a home to go to?:)


  2. May 15, 2018 @ 11:13 am David

    I know that you do not sell the supercharger system for the TR6 anymore because of the inability to get the Holley carburetor. Have you considered re-introducing it with something like the FiTech 2-barrel EFI system? Theoretically a “drop-in” for the Holley but with adaptive learning fuel injection. Sounds like a winning combination to me. It would cost me ~$1200 for the EFI system complete but you could probably get it for a bit less as an OEM. Just a thought.


  3. July 7, 2020 @ 10:52 am Dick Taylor

    Interesting that Moss said the reason for discontinuing the SC was from a short supply of the Holley 350 carburetor. When I asked Mr. Goldman why Moss didn’t use the SU-HD8 carburetor he told me “there may not be enough of them to supply the SC kit.” He also showed me a F.i. setup he (and Moss) was working on, that looked promising. That was late 2018.

    Dick Taylor
    ’73 TR6 Turbocharged


  4. August 17, 2020 @ 12:30 pm Jeff

    They have GM TBI conversion kits for the TR6 available. They should make it mountable to a GM TBI and program a TBI setup and get rid of that horrible ignition at the same time. Can you sell a kit with just the pulley, intake minus the supercharger? I could make up the rest


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