FORD RS Turbo Series II Tuning Guide

The RS Turbo is a serious car as a base for tuning. There are a number of simple and not so simple modifications that can be made to increase the power output of the vehicle.

• Actuator

A standard RS Turbo Series II should run with approximately 8psi of boost pressure. This is the setting at which the wastegate starts to open, allowing excess gasses to bypass the turbo. By simply uprating the turbo actuator a higher boost pressure can be run as long as this boost pressure does not go above the over boost sensor setting. The over boost setting depends on which boost control unit the engine is using. The later RS Turbo models allowed a higher boost to be run of about 10.5 psi. The boost control unit is located behind the cockpit ventilation intake unit and is to the left of the injection control unit. It has a single boost pressure sensor pipe leading to it. The later model boost control units have a "hash diamond heart" logo visible on them. These were fitted to the 90 spec RS Turbos. By fitting a 10.5psi actuator the engine should increase its output at the wheels from 130bhp to around 145bhp. To increase the boost above the default over boost setting a chip is needed in the ECU to fool the system into thinking the boost is lower that it real is.

• Chip

A chip is needed to run the boost above the default over boost setting of the boost control unit. There are many different manufacturers of chips: TurboBoost, SuperChips, BBR, Collins. With a chip an uprated actuator can be used to allow the wastegate to open later and hence run the turbo at a higher boost pressure. It is normal to run the boost at around 1bar (15psi) but the standard engine can be taken further than this if a higher pressure copper head gasket is used. A chipped RST with 15psi of boost will be producing around 165 to 170 bhp at the front wheels.

• Silicone Hoses

When higher boost pressures are used it might be found that some of the older turbo inlet and exit hoses are not up to the job. The turbo creates a lower than atmosphere pressure as it sucks in the air from the air filter. On older or perished original inlet hoses this can cause the rubber to collapse as the turbo starts to suck harder or the opposite on the boost side. To solve this problem fit uprated silicone hoses.

• Larger Intercooler or charge cooler

A must for all highly tuned RST's is a larger intercooler. As described previously the intercooler sits between the turbo air exit and the engine inlet. Its purpose is to cool the compressed air charge before it enters the engine. With higher boost pressures the standard intercooler fails to reduce the temperature of the inlet air sufficiently and becomes a restriction point. Bascially by fitting an uprated intercooler the inlet charge temperature can be reduced allowing the engine to producde more power. Remember the more air you can get into the engine the more fuel you can inject hence the more power you produce. One of the problems with the RS Turbo is the room tuner have to use in the tight engine bay. This does not help to keep the engine cool and adds to the problem of fitting a larger intercooler. A way around the space problem is to replace the air-to-air intercooler with a Pace chargercooler. This relies on a air-to-water radidator which uses its own water feed and small pump to keep the extra air-to-water heat exchanger cool. The RS Turbo has a engine safety feature built into the induction system. A charge temperature sensor monitors the air temperature just before the thottle position sensor, if this increases about the critical point of 68DegC the boost control unit lowers the maximum boost to 3psi. The only way around this feature is to let the engine cool down or get the charge temperature lower by fitting a charge cooler or larger intercooler.

• Competition Spark Plugs

It is recommended either Champion or NGK Competition spark plugs are fitted. The gap on these should be set to 25thou before fitment. Higher boost pressures can actually blow out the spark if the gap is not set correctly.

• Big bore exhaust

Another simple but not cheap modification is to fit a big bore exhaust. Well known makes are: Magnex, Scorpion and Mongoose. All allow a greater and less restricted exhaust gas flow, with a much improved engine note! Similarly with the K&N filter this allows the engine and turbo to run slightly cooler.

• Uprated Cam

Once the above modifications have been made it is recommened to fit an uprated cam. Two well known makes are suitable: Kent or Piper. Both companies make uprated CVH cams designed for the RS Turbo. Note the above modifications would take a well setup RS Turbo to a front wheel output of close to a max power of 195bhp.

• Dump Valve

Although a dump valve in itself will not increase power it reduces the effects of turbo lag between gears. When the turbo has fully spun up and is pushing its maximum boost to the engine when the throttle is closed during a gear change the turbo will start to push against a dead end. This causes the turbo impeller to loose revs and spin down. When the next gear is selected and the throttle again opened the turbo will need to spin up to its boost pressure again. By fitting a dump valve the turbo can keep spinning since the valve is releasing the built up pressure to atmosphere. This hence reduces the lag of the turbocharger and allows the power in the next gear to come in much quicker. Note: During very severe driving and higher boost pressure the dead end effect of a closed throttle can cause the turbo impeller to shatter due to the high pressure it will create.

• Uprated Clutch

Quite often with an uprated engine it becomes apparent that the clutch is not up to the job of transmitting all the new found power to the gearbox. This is even more of a problem of cars with higher mileages and original clutches. It is recommened that a new uprated item is fitted.

• Fifth Injector

To achieve over 200bhp the RS Turbo engine requires a higher fuel input than can be achieved by the standard four injectors. To go above 200bhp a fifth injector is required. This injector comes in at higher boost and revs and lets the fuel system supply more petrol to the engine. Make sure the fuel filter is in a good state of repair as an old or blocked filter can restrict the fuel flow to the injector system.

• Hybrid Turbocharger

When higher boost pressures are used it is recommended a turbo with a 360 degree thrust bearing is fitted. This allows better lubrication and support for the turbo and hence longevity. A hybrid turbocharger generally uses a cut-back exhaust shaft wheel. Hybrid turbochargers can be purchased from: TurboBoost, Turbo Technics

• Water Injection

Real power hungry tuning fans also tend to fit a water injection system, such as Aquamist. This system injects a spray of water into the inlet of the engine which cools the charge and combustion temperature.

 1900cc Low Compression block

For the ultimate bhp fit a overbored 1900cc low compression block. All the previous tuning tips have concentrated on squeezing ever more power out of the standard 1600cc engine. Once all other avenues have been explored then why not uprate the standard block to 1900cc? At the same time it is recommended to fit an uprated copper head gasket to allow boost pressures about 15psi.

• Brakes

All good tuning projects also include brakes and suspension improvements. A must for a tuned engine is a uprated braking system. As a minimum it is recommened that fast road brake pads such as Mintex 1144 or the newer developed Ferodo DS2000 are fitted. Better still are drilled and/or grooved front disks. Even better still are larger front disks with uprated Cosworth calipers or AP four pot calipers. A simple mod is to use braided hoses and higher specification brake fluid.

• Suspension

If the engine is tuned it is also a good idea to uprate the standard suspension components. Running higher boost pressures on a standard suspension setup will really push the car. One of the best modifications is to fit top adjustable Spax dampers with lowered and uprated springs. Any more than 25mm lowering and the ABS system will need adjusting to re-tension the ABS belts.

• Replacement Bushes

To enhance the handling still further it is best to fit polyurethane or nylon bushes to all supsension components. The original Ford rubber ones will perish and deteriorate over time adding unecessary movement to the suspension components. The front anti-roll bar mounts and Track Control Arm to anti-roll bar bushes are easily replaced and will greatly tighten up the front end. The rear bushes are all harder to replace!

• Strut Braces

Strut braces can be fitted to the front and also rear turretts to stiffen up the body. Be careful of purchasing cheaper items particularly for the front since poorer quality items may not fit very well. Ensure all turbo pipes are routed properly around the front strut brace.