A dyno simulates road conditions in a controlled environment, giving the operator the ability to monitor many different variables: power on the wheels (front, rear or all four wheels), air/fuel ratios, instant ignition timing per cylinder, engine temperatures, inlet air temperatures, boost temperature, and others. The dyno technician can diagnose and assess various engine functions and problems as well as to see if there are improvements that can be made – under load, as if the car is being driven on the road. The technician can then adjust various settings such as the amount of fuel injected into the cylinder, the ignition timing, boost levels, and then retest to see that all the changes made register improvements.
Most modern engines are fully computer controlled and no adjustments can be implemented from the outside. This is where the Unichip piggyback ECU comes into play. The Unichip computer interfaces with the standard engine management system allowing us to programme every vehicle individually to suit the client’s requirements. There is a timing circuit, fuelling circuit, throttle position circuit and five additional input/output circuits so that the tuner can adjust various other parameters such as VVTC (variable valve timing control), V-TEC control, boost control as well as giving us the facility to remove the road speed governors on various vehicles.
When installing a Unichip we begin with a blank map so all the signals going in or out are standard. Our dyno technicians then begin the mapping process and will concentrate on total remapping as well as the areas where there are flat spots or ‘holes’ in the standard maps.
There are 24 rpm sites and 13 load sites (excluding the closed throttle and full throttle sites) on a Unichip. This allows for more resolution in a specific rpm band so they can be adjusted closer to each other: on a race car, for example, you wouldn’t be very interested in what goes on much below 2 500 rpm, but you’d want to map at – for example – at 100 rpm intervals in the vicinity of the engine’s power peak.
Fuelling, timing and boost are adjusted live so you can get the best out of each vehicle individually. Full throttle tuning is done for maximum safe power and below that we set the vehicle up for maximum efficiency regarding fuel consumption and drivability (throttle response). Different map options can be installed for different fuel grades and for the use of products such as Torco. RGM firmly believes that the Unichip is a unique computer system that is changing the way clients can have vehicles set up for their individual needs.
What is a dynamometer? Steve Green, RGMotorsport’s tuning guru, explains
A dyno (as they are commonly known) is a device which measures speed and torque and calculates kW from the two. No dynamometer measures kW – it is always a calculation.
You get two kinds of dynos: inertia and load. The former simply bases its power figure on how long it takes the car to accelerate the dyno – with the engine at full throttle -- up to a specified rpm in a specified gear, and then return to standstill. On any rolling road dyno the car is secured on a roller or rollers (which are of a known weight – an essential fact in calculating the power). Because inertia testing is conducted at full throttle, it stands to reason that no tuning can be carried out during a run: you have to complete a run, allow the rollers to return to standstill and then make a change. You have to keep on going through this process until the desired result is achieved.
Because a road car only sees full throttle – at most - 10 percent of the time, part throttle tuning is the key to driveability and economy. A load dyno allows the tuner to hold the vehicle at any rpm at any throttle position in any gear to simulate road conditions and driving styles, and then make livechanges to achieve the desired result.
With this process, things such as throttle response, fuelling at various cruising speeds and a whole lot more can be influenced and improved by changing ignition timing and fuel supply. A skilled tuner can use a Unichip to optimise engine settings at multiple points in the rev range. Time permitting, this could even be done every 100 rpm.
The load applied to the rollers and therefore to the cars tyres is influenced by the dynos design and different dynamometer manufacturers have different philosophies and methodologies in this regard. While the objective is to calculate kW (which has an absolute known value), there is some variation and therefore not all devices will read exactly the same – this makes it pointless to compare the results achieved on one dyno with those achieved on another as it is a case of apples and pears.
RGMotorsport is in the fortunate position of having two sophisticated load/inertia dynamometers; one of which is a four-wheel-drive type and therefore ideal for both off-road vehicles and high-performance all-wheel-drive cars. On a load dyno you can switch off the load brake so that it can be used as an inertia dyno if necessary, but the opposite is not possible – an important fact!