Smaller engines generally have little scope for tuning. When you exceed the base output of the engine by a factor of 25-50% more you may start to hit reliability issues. It pays to use good quality performance parts and sadly each performance modification will reveal a weakness elsewhere in the car.
Our overall aim in tuning is to provide a good compromise between the peak power, fuel economy and long term reliability. We look jealously on at motorsport teams and the heady power figures they achieve. We need to remember that these cars are stripped down and rebuilt after each race, or at least a few times in a racing season.
The greater the capacity and horsepower the larger the amount of power gains open to you. Turbo engines represent the best potential for power increase as a remap will change the timing of the engine as well as the wastegate control (forcing more air into the engine) and fuelling. Often a remap of a standard turbo engine can provide reliable power gains of up to 50% base power, equating to around 50-75 extra bhp. On a naturally aspirated engine you will get a much smaller power gain for the same money. Expect to pay around $500, £300 for a remap whereas to get a 20bhp power increase on a NASP engine you are looking at 2-3 times this amount.
- Turbos,
Remap the turbo, fit a larger or aftermarket turbo, uprate the exhaust and fit an induction kit. Cams, head work and bottom end strengthening are required for power hikes of 50-100%. - NASP (Naturally aspirated engines)
Ignore all smaller engines (sub 1600cc engines unless they have a high red line around 7500 rpm). For all engines over 1600cc you should fit (in this order) fast road cams, full sports exhaust, induction kit and get the head gas flowed. Finally when all other modifications have been done address the engine timing with a remap. A big valve conversion and head work will further increase the power output. (If you want to add forced induction your best bet will be a supercharger kit.) - Rotary engines.
These are very high revving and are fairly tolerant of power increases. Look to improve the flow of air through the engine with a full exhaust and induction kit. Uprating the fuel pressure and injectors will allow bigger gains to be made. Gas flowing the engine will also improve things a little but most rotary engines are well machined to start with.
General notes:
Traction can be a big problem on FWD cars. With front wheel drive cars
exceeding 250bhp we would recommend substantially wider tyres and
slightly softer suspension. A carbon fibre driveshaft will also help to
put the power down more smoothly.
Gearing. When increasing or changing the Torque curve of an engine it is best to alter the gear ratio’s to allow you to better exploit the power. Lower ratios will nearly always give better acceleration.
