By Loren Dewey
Chapman Report – April 1980

An unusual set of circumstances brought this conversion about. First, an Esprit burns, second low oil pressure, last, but not least, the lousy gas available today.

Fellow GGLC member, Stan Murawski, had his Esprit burn, so he parted with this RayJay 302B turbocharger which was intended for the Esprit. My Europa still had low oil pressure after replacing the oil pump and lower end bearings and it pinged like crazy on any gas – missed or otherwise. The most reasonable thing to do was to rebuild the engine and add the turbo with lower compression pistons. The car had been down for several months while the engine work and an extensive engineering change was performed on the rear hub carriers. So, the thought of more down time was very unappealing. The best option open to me was to obtain another engine and install it in the car while installing the turbo and rebuilding the original engine.

The plot thickens! There were not R16 engines in any of the wrecking yards in the Bay Area, or at least I couldn’t locate one. Only a ’78 R17 from a car that had burned. (Fire seems to play a big part in this tale!)

Scene two opens with an R17 complete with everything except alternator, starter and cam drive pulley on the garage floor, a turbocharger on a wood block in it’s approximate position and me with scratch pad and ruler. The R17 was then stripped of exhaust system, motor mounts, smog pump, miscellaneous injection hardware. The fuel injectors and stacks were retained because it was thought that the long induction tract might cause a cold start problem. The plan was to build a new exhaust manifold to accommodate the RayJay, a plenum to match the injection stacks and an adapter from a Holley Weber carburetor to the supercharger.

The exhaust manifold is made from a 0.250 inch steel plate cut to match the exhaust port and bolt pattern of the head. 1 x 2 inch tubes were used to connect this to a 2 inch square log. These sized were chosen because of the port shape and material convenience. A short tube and flange was added to mount the turbo. The intake plenum is aluminum and was constructed with stub tubes to match the injector stacks and 2 inch tubing. There are neoprene couplings between a steel crossover pipe, the turbo and the plenum. The carburetor adapter is aluminum and fabricated of telescoping tubing, a machined flange and a cast VW carburetor adapter.

With all this complete, it was time to install it into the car. The R17 uses different motor mounting points, but the holes that match an R16 are there, and all went as planned. The left water pipe was cut off and hose replaced it to make space for the new exhaust manifold, etc. The heater hoses were replaced because different lengths were required. Once in place, the plumbing starts; an electric fuel pump was added, move the coolant swirl tank to the rear and connect everything. The battery was moved and the cables to the starter were rerouted away from the turbo heat. A water injector was made from a windshield washer pump, a coolant recovery tank and a Buick Century pressure switch (adjustable from 0-15 psi). Oil to the turbo comes from the idiot light switch hole and returns to a mysterious hole in the block that could have been used for a dipstick. A new throttle cable was made from a motorcycle clutch cable (available in bulk). And, the exhaust pipe was last, but a long way from least! Space for a 2.25 inch pipe which comes out of the turbo forward is hard to find. I won’t go into it’s route except to say that to install or remove is everything on the exhaust side of the engine must be removed including the exhaust manifold.

For those of you unfamiliar with the Renault R17, it is a 1700cc engine with a crossflow hemi head, under 9:1 compression ratio and in Gordini tune claimed 95 hp at approximately 6500 rpm. The design criteria for this project was for a turbo boost of 11 psi which would, on paper at least, produce 180+ hp. Well, I have a problem, because the pressure gauge has seen 14 psi. Too much boost! But, if you have a problem, this is the best kind… ie. Too much HP!

The driving performance of this conversion is sparkling, but not spectacular. (It won’t win a drag race with a Chevy V8 powered 914 that I know of, or other street dragsters). It is, however, very pleasant and got 26 mpg on the first tank. At this time, it is still in the debug stage with unknown things like the best spark advance curve, carburetor jetting, cooling and boost limiting requirements. All take time.