Wednesday, January 13, 2010

Performance engine tuning modifications

Careful selection of the internal tuning changes may cause some supermarket system Cruiser Rally Spec, flame-spitting, mud .......

While it is tempting to throw in every modification you can it's worth noting that they don't always work well together

ie: a gas flowed head with a sport cam produces less power than it would with just one of the two modifications if the cam profile is not carefully matched to the head flow rate.

You want to avoid ending up with a high peak BHP power engine that has an unusably narrow torque band. Peak power is only part of the figure, one should really look at the torque curve and aim to get this as flat and wide as possible for a predictable power delivery. A lot depends on the engine configuration and the driver/driving conditions to be encountered.
You want to avoid ending up with a high BHP engine that has an unusably narrow torque band! Rather than look at a peak power figure attention should be paid to the torque curve.

So how do you make a car go faster? Aside from pushing the accelerator pedal harder there are some basic things that can be done. The internal combustion engine works on the principle suck,squish, bang, blow.

Air is drawn in to the engine (this is the suck stage) then it is mixed with Fuel and compressed (the squish stage) – then along comes a bright spark and the intake charge ingites (the Bang phase) is achieved – releasing all that compressed energy which forces the piston down and the air out of the engine along the exhaust (this is the Blow stage).

It is possible to blow huge amounts of money on a car ruining it and ending up with a fuel drinking stodgy bone shaker that looks like a Christmas tree from last year. TorqueCars intends to assist you in deciding which mods to do. We are comitted to give you a realistic opinion of what the car will end up like and we give a common sense guide on the pitfalls and common mistakes to avoid.

Our forum is a great place to learn more about car tuning and styling where you will find lots of very friendly and helpful people.

Track cars are rebuilt each time they are raced and they are set up for optimum conditions on the flat surface of the track - we have to tune our cars to work for a year without a service, run over potholes and speed humps and cope with a variety of weather conditions and loads. We need to establish the sensible mods that will cope with everyday driving but help you to get the maximum enjoyment from it.
Internal engine tuning modifications

Items include high compression pistons (increase the compression ratio).

Low compression pistons (reduce the compression ratio and used with some turbo applications to prevent ignition problems and reduce the effects of turbo lag.

Skimming the head also increases the compression ratio and to avoid detonation with low octane fuel a low compression piston is used. Read more on internal engine mods
Gas flowed head

The internals of the head are polished and channeled to allow the induction charge and exhaust gases to flow more freely. Inlet diameter and other measurements are taken and the best flow rate is calculated and the engine channeled out accordingly smoothing the internals and sometime a little turbulence/swirl is added to ensure a good air/fuel mix inside the combustion chambers.

Specialists can increase EITHER the peak torque/bhp output of the engine which gives a nice headline figure or spread the peak Torque/bhp band which gives a much improved drive. We would say to ignore the peak power figure and look at getting a nice wide and flat Torque band accross the rev range.

You can also have EITHER improved and a slightly lower power figure or tune the engine to the max and get reduced fuel consumption. Sadly you can't have everything you have to decide what the optimum rev range that you use is then specific gains can be generated in that area by flowing the head.

I had my 2.0 T series head flowed for Torque gains across a wider spread of the rev band, where peak torque now comes in almost from 1000 revs. I have also got much better fuel consumption - up by a stonking 10mpg (Other work has been done on the Head which also contributed to this gain)!!!

I do not seem to have more power in the higher rev bands so the headline power figure was not great up near the redline but I never really go that high so my engine is perfect for my driving style. The angle of the inlet valves, enlarging the inlet and exhaust valves and increasing the lift on the valve can all aid the way gases flow into and around the head.
Re bore

The cylinders to create a higher capacity engine – check that your engine management system is able to cope or can be adjusted to suit this will also require work on the pistons as they will need to be switched for wider ones. A stroker kit also increases the cylinder capacity and typically comprises conrods, crank and pistons and generates more space in the cylinders for air and fuel. More on engine rebores
Crank grind/polish

While the crank is ground it is worth balancing all of the other internals of the engine - your redline will be higher if the engine is balanced and a lighter polished crank gives less friction and releases more power from the engine.
Sport computer tuning

Changes the timing characteristics of the engine and is usually perfectly matched to your engine, fuel choice, driving style and car condition rather than the standard makers best guess setup which can cope with pretty bad servicing and poor quality fuel. Massive power gains and better fuel economy are available as is a high revs sport power setting and a low revs economy setting.

The downside is that you have to keep the engine in peak condition changing the plugs regularly and fastidiously following the service intervals. The cars which benefit the most from a sport computer are those which are fitted with a turbo or supercharger.

You can buy a standard plug in chip but it is much better to have the sport ECU set up specifically for your engine and have a custom map - again this can be set up to give better fuel economy, a lower peak torque cure, better acceleration or higher top end power. Some ECU's are impossible to reprogram without the manufacturers diagnostic equipment - the Rover MEMS is a point in case.

If this is the case with your engines computer you can add a piggyback device which gives false readings to your cars ECU and takes over control of Fuel, Ignition and boost control. More on ECU tuning
Port Matching

Port matching adjusts the diameter of the exhaust and inlet ports to match the profile on the manifolds which are nearly always bigger. (Don't take out the V groove as the torque will drastically reduce! The aim is to allow a smoother flow of air without the turbulence associated with having a step between the mating surfaces. More on port matching

A sport or fast road camshafts increase the duration of the valves opening and closing the engine is best suited to higher revs and can cause a stodgy tick over. Cam profiles vary from fast road to full race. One of the most cost effective and noticeable modifications you can do. We explain the many profiles available and the typical effect it will have on performance. More on camshafts
Forced air induction.

A turbo or supercharger forces air into the engine at a greater pressure and more air and more fuel = bigger bang = more power. Turbo chargers use the force of the expelled exhaust to drive a turbine and ram fresh air into the engine. Superchargers however are driven by the engines drivetrain.
Turbos vs superchargers

Superchargers give an increase at all revs the higher the revs the more induction charge there is and turbochargers have the same effect although lower down there is what is known as turbo lag – where the effect of the turbo cuts in at a higher rev range.

Turbo chargers produce more power than supercharges but most modern engine would need an engine management computer upgrade to be able to handle the altered air flow – the fuel injectors would need to run at a higher pressure to get the fuel into the now pressurised combustion chamber. More on air intakes

When you increase the power of an engine you will need to increase the amount of fuel it has to work with. You will usually need to uprate the injectors and fuel pump. The mix ratio of air to fuel needs to be closely balanced and most engine tuning projects will involved increasing the amount of fuel and air combusted in the engine