Modification Modification
Car: Ford | Fiesta | CX (Mk3) | RS Turbo | Hatchback
Engine: CVH | 0 | Inline 4 | (EFI) | Turbocharged | Petrol

T3 Conversion

I purchased the car without a turbo, and for me fitting a standard T2 was not an option. Shaft speeds on the turbo are very high past 10psi, and this combined with an inadequate oil return means that turbo life is severely compromised. As T2's are prone to failure, especially on chipped cars, good second hand units are both rare and expensive.

Another reason for going T3 is that the unit is much more suited to the engine, the boost threshold is slightly higher than that of the t2, but it really is negligible when out on the open road. The T3 won't leave you short changing into 4th like the T2 will, and gives a broad powerband that is very useful in everyday driving.

Red Fiesta RS Turbo Restoration

Air filter

The T3's orientation is exactly opposite to that of the T2, meaning the standard airbox cannot be used without considerable modifications to the inlet pipe work. The standard airbox has been used in some cases, although it makes for a long length of induction pipe work with some nasty 90º bends.

My solution was to attach a universal air filter directly to the neck of the compressor housing inlet. The filter has a low profile so that it can clear the upper radiator hose. Another way is to cut the FRST inlet hose and use that to place the filter above the gearbox.

I cut a circle in the top of the filter and used a 90º fitting to connect a breather hose, which runs back to the stock breather pot near the inlet.

Red Fiesta RS Turbo Restoration

Boost hose

As with the inlet, the compressor outlet is in a very different position to that of the T2. To join the outlet to the intercooler inlet I used a mixture of old exhaust pipe and the blue silicone hose that Ford use on the T2 installation.

I used two slightly curved pieces of pipe, and measured them to create the a tube with the required skew. Once welded together and the rough edges filed smooth, the FRST silicone hoses were cut to suit and clamped on.

Red Fiesta RS Turbo Restoration

Coolant hoses

My choice of air filter meant that I had no room for the standard top hose with its turbo coolant feed. I had no plans to run water cooling on the T3 anyway, as this tends to put too much heat in to the cooling system. Removing this has no detrimental effects providing the turbo is left to cool down after a run.

I used a top hose from a 2000 Honda Accord VTEC (left), when cut it is a near exact match but without the lower take off that fouled the filter.

Red Fiesta RS Turbo Restoration


I cut off the front section of original exhaust as close to the fixing clamp as possible and used an Escort T3 down pipe and cut that as close to the FRST exhaust as I could (left). I then welded the two sections together.

I found it much easier to tack everything in position on the car, and then lower the exhaust from the turbo back in order to seam weld the join. I used a Magnex stainless exhaust as it offers perormance gains over the original without being any louder. It also looks a lot better.

Red Fiesta RS Turbo Restoration

Radiator positioning

The T3 actuator bracket fouls the radiator, in fact the turbo cannot even be fitted unless the radiator is moved to accommodate it. Further room is required to take engine movement into account, if this is not done the radiator will be ruptured by the turbo during hard acceleration.

The FRST rad is held to the slam panel by 3 brackets, I removed the centre one so that the radiator and intercooler can pivot outwards in the middle, leaving an extra inch of room in front of the actuator.

In order to give the rad enough clearance to pivot outwards I had to bend the bonnet catch support bar, as the photo (above left) shows. When the radiator is finally in position the turbo has enough room to move.

Red Fiesta RS Turbo Restoration

Mounting the turbo

The T3 bolts directly in place of the T2, and the same studs can be used. I initially used the T2 manifold gasket that was supplied with a top end gasket set, however the port cut-outs were too large and the turbo did not seal. The Escort RST gasket is needed which is Ford part number 1023231.

The escort oil feed line (1630538) is required, as is the oil return connector (1630538).

Completed conversion:


Red Fiesta RS Turbo Restoration

To make the most of the new T3 conversion I fitted a 'stage 0' or '165' chip. The chip plugs on to the data port on the bottom edge of the EECIV ECU. A 165 chip simply removes the factory standard 9-10psi boost limit.

The OEM intercooler, pistons and fuel injectors can safely support 13psi and 180bhp, but to err on the side of caution I set up the car to run 12psi. I cannot stress enough that the car must be in good health before chipping is carried out, this means a good fuel pump, good fuel pump wiring, correct CO level and good compression. The difference over the standard car is like night and day, a very noticeable increase in performance.

© Mark Stewart, Wednesday 15th June 2005
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