So you've seen an Mi16 powered 205 or 309 GTi and want one yourself.

Good decision, but what exactly is involved? How difficult is the conversion and how long will it take?

Firstly, this is what you can expect:
- Supercar Performance!
- 0 to 60 in under 6 seconds, or under 5 with a modified engine
- 150 mph

The conversion can be completed by any competent mechanic. There are several main areas to consider:

1. The base car - start with a GTi (or CTi) model as this has the easiest specification to work with. If you start with a non-GTi model you will have a non-injection wiring loom, inadequate front suspension (the design is different and you will need to swap to a GTi sub-frame assembly to change this) and narrow wheel arches. You will also have fewer engine ancillaries that can be re-used. The GTi suspension and braking capabilities are easily able to cope with the 16v power (until you modify the engine that is!).

2. The donor 16v engine - make sure you buy an engine with all the ancillaries, plumbing, wiring, ECU and other control components you need. These are costly to source separately. Your requirements will depend on how you intend to run the engine (see below). Unless you know the engine history, it is worth at least fitting a new set of valve stem seals, head gasket and cam belt. Also fit a new clutch while the gearbox is off.

3. Fitting the engine - drop the old engine out under the car. Mate the 16v to the 205 gearbox. Use a 1600 gearbox for lower ratios, 1900 for higher top speed and more relaxed motorway work. Note that the 1600 has different driveshafts and hubs to the 1900, so swapping gearboxes means swapping these as well. Lift the 16v up into the engine bay. The engine mounting points are the same, but you need to replace the bottom engine mount bush with a hard rubber version, to stop the cam covers hitting the master cylinder under accelleration. Use the Mi16 alloy engine mounting brackets and fittings.

4. The exhaust manifold - the Mi16 exhaust manifold hits the 205 bulkhead. You can cut and fold back the bulkhead lip and re-shape the bulkhead behind the manifold to relieve this, but it leaves a very unprofessional finish and is asking for rust to get a hold along the seam. Unless you re-weld the bulkhead seam, it can also leave this area weakened.

Do not shorten the bottom engine mount as this can cause oil starvation problems under heavy cornering.

For the best job and better power, buy a bespoke exhaust manifold. This may be the most expensive part of the conversion, but it is definately worth it for the extra torque, power, ease of fitting and professional instal look.

5. The radiator - you can make up some brackets to drop the radiator away from the 16v inlet manifold, if you run the engine on its standard injection. If you run sidedraught carbs, there is no need to do this. If you are running standard injection, the best bet is to buy a shorter 16v inlet manifold to save moving the radiator and this also gives better torque. You can also swap the radiator for a Citroen BX 16 valve unit, which is wider and lower. You will also need to make up brackets to fit it - it doesn't bolt straight in.

6. The plumbing - you will need to use a combination of 205 and Mi16 coolant hoses to connect everything up, including the Mi16 water cooled oil cooler if you are keeping it ( although you are better to use the 205 1900 air cooled oil cooler, or buy an oil cooler kit). Use the 205 header tank. There's no right way to do this, you can finish it a number of ways. Just be resourceful with the hoses you have from the 205 and Mi16 engines, as new hoses are very expensive. Obviously replace any that are not in good condition.

7. The wiring - this is the bit that scares most people unfamiliar with car wiring systems and there are two ways to approach it. Firstly, you can retain the 205 engine loom and buy a distributor conversion plate to use the 205 distributor. This is by far the easiest and quickest way to wire the mi16 engine in as it then uses all the existing 205 ignition components.

Alternatively, use an Mi16 engine loom and the Motronic 4.1 ECU that comes with it. This requires an amount of wiring in and is not recommended if you are unfamiliar with car electrical wiring systems. However, you can end up with a very professional conversion, using all the original Mi16 ancillaries and control systems.

8. Enjoy harassing innocent drivers of more exotic machinery!