Given that a junkyard turbo costs about $30 - $50, an average garage mechanic with very little money, a little bit of time and some creativity can transform a wallowing pig to a howling coyote (I certainly was howling when the car took off)!
The idea of putting a turbo in a Triumph TR6 is not new. In the 80's Kas Kastner offered an aftermarket turbo kit using a 2" SU carb and an Arkay turbo. It could produce 200 HP at the rear wheels with race gas, water injection and 15 pounds of boost. Pretty impressive results considering the HP that was being generated in that era.
Start with your basic stock (engine that is)
My stock was only slightly seasoned with:
None of these items are required; it was simply how my stock
was seasoned.
At this point I was getting: 85 HP at 5000' (about as
exciting as soggy toast)!
Add a little HOT sauce:
I seasoned generously with:
The results are a Piece d'Resistance!
205 HP at the rear tires using pump gas and 10 pounds of boost (this is equivalent to 7 pounds of boost at sea level).
This picture shows the left side of the engine.
The front aluminum shroud covers an aluminum radiator, oil
cooler and the intercooler. All of these components are mounted
at a slight backward angle to maximize heat transfer. The
mechanical fan has been replaced with a electric fan that is
controlled by the Megasquirt computer.
The coil has been replaced with an EDIS 3 coil pack from a Ford
Econoline van. Since the ignition is computer controlled the
distributor has been cut down to maintain the tachometer output
and topped with and aluminum cap.
The large cylinder in the lower left corner is an Accusump (on demand pressurized oil reservoir) and was NOT required for the turbo.
This shows the turbo installation from the right side both with and without the intake manifold. The engine bay is long but narrow and the waste gate actuator had to be reversed to get it to fit. I simply removed the lever arm from a junkyard turbo and attached it to my turbo at the desired angle. It is an easy process, however, all of the parts are stainless and require the correct welding techniques.
The basic building block for the intake manifold is a 2.5 PI Triumph plenum that I imported from England. The plenum has 6 runners; each runner is approximately one inch long and has a flared inlet. The plenum on a stock mechanical Lucas PI system is attached to 3 sets of cast aluminum intake manifolds. Each manifold has twin butterfly valves and the 3 sets of manifolds are linked together. I found that with a little throttle shaft wear it is difficult to accurately balance the butterflies. To reduce balancing problems I decided to use the same methodology used in today's production vehicles; a single large diameter throttle body feeding a common plenum. I started with 1.5 inch O.D. exhaust tubing and flared the tubing on one end to approximately 1.75 inches (inside diameter of the runners for the plenum intake). The small diameter side of the tube was welded to a 3/8 inch steel flange, the large diameter side was ground down to a sharp edge and brazed into the plenum. The two brazed breather tubes were replaced with threaded a pipe couple for an air temperature sensor and a manifold pressure tap for the blow off valve. An additional couple was brazed on the rear of the plenum as a manifold pressure tap for the brakes and computer. A flat flange was welded onto the inlet to accept a Ford Mustang throttle body. The Mustang throttle body was selected due to its availability, low cost ($15), very short compact design, and a large number of after market vendors that sell larger diameter replacement units.
This is a photo that illustrates the overall engine bay
configuration. Here you can see the routing of the turbo oil
tube, and throttle cable. The air filter, plenum, turbo and
intercooler inlets are all in-line to avoid any unnecessary turns
that cause pressure drops.
The aluminum radiator is a cross flow design without a filler
neck. It was mounted with both the inlet and outlet on the
passenger side and is filled via a Chrysler thermostat housing
with filler top (additional info and photos follow in a later
section).
The intake runners were designed for use with a Bosch fuel injector that provides a focused stream of fuel in a tight pattern. The injector holder is aligned such that the fuel is sprayed onto the back of the intake valve. The intent is to reduce wetting of the intake wall and to use the heat of the intake valve to aid in fuel vaporization.
This is a 90-degree transition tube that bolts to the turbo
outlet. It is constructed from S-glass, carbon fiber and a high
temperature poly-vinyl ester (Derakane) capable of withstanding
350-degree temperatures and harsh chemical environments.
This 90-degree tube provides an increasing cross-sectional area
that minimizes pressure drop. The base
flange is constructed from an aluminum / composite matrix to
ensure mechanical strength.
This is a close up of all of the carbon fiber interconnect tubes. The complex design and variable cross sectional areas would have been nearly impossible to construct from metal without the use of casting techniques. The arrows are color coded, green indicates turbo inlet air, red is turbo output air, and blue is intercooler outlet air. The blow off valve dumps cold pressurized air back into the inlet thereby providing some adiabatic cooling to the inlet air.
This shows the method used to build the 90-degree transition tube. This photo illustrates four stages in the construction process: follows:
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