EcuTeK DeltaDash Road Dyno feature (from hereon abbreviated to DDRD) allows real life performance testing of any manual transmission Subaru vehicle supported by DeltaDash. This enhancement to DeltaDash is a free upgrade available to new and existing customers via software download from the EcuTeK web site. No hardware is required, other than the standard hardware supplied with DeltaDash.
In addition, due to the way the DDRD does its calculations, it is unaffected by any piggyback ECUs or speed delimiter modules.
DDRD measures engine speed reported by the ECU, many times per second. Based on this, and additional data about the car, such as tyre, gearbox, drag and weight, DDRD can calculate many statistics about the vehicle's performance, based on a simple full throttle in gear test of the engine on the road surface of choice.
DDRD will calculate the following statistics:
Use of DDRD is very simple. Before driving the car, the software must be setup with various physical characteristics of the vehicle in question, such as tyre size, gearbox type, rev limit, mass and drag data. These vehicle characteristics may be selected simply from lists of available options for the various car models. As long as you know the model of car you are driving, this is very simple to do.
Once this data has been entered, DDRD will display a graph showing the vehicle speeds achievable in each gear. This is as much as DDRD can tell you about your car until you perform an in gear test of the engine - see below.
Gathering performance data about the vehicle involves driving the vehicle from low engine revs (say 1000 RPM) up to any higher RPM that you choose. Before testing, ensure that you have selected the gear you have decided to test in - this is labelled 'Test Gear'. To perform the test, select the 'Setup & Data Capture' tab and from a steady cruising speed, when you are ready, click on start test. You must then reduce speed until the engine drops below 1250 RPM. Once the engine revs have dropped low enough, the test will begin. At this point, the driver must accelerate in the chosen gear. No gear changes, braking or clutching should be performed during this test - the test is from low revs to high revs in a single gear.
This will require two people - one to drive and one to operate the laptop. Do not try to do this alone.
Once the performance test has been done, clicking on the 'Data Analysis Graphing' tab will display a vehicle performance graph. The axes of this graph may be altered to show a wide variety of statistics. The most common graph for comparing vehicles will be Power & Torque against Engine RPM or Vehicle Speed. Preferred units of measure may be selected at any time - Power in BHP, PS or kW, torque in Nm, LbFt or kgm. When viewing power & torque, the power is the bright line, whilst the torque is the more feint line.
Selecting the next tab, 'Performance Report' shows various facts and figures about the car. These may be cut & pasted for use elsewhere.
Test data and the entered vehicle characteristics may be saved at any time using the 'Save Data...' button. Files may then be reloaded and edited using the 'Open Data File' button - this allows editing of the vehicle characteristics, should any previously entered data be found to be incorrect.
Getting Accurate Results
Tyres & Gearbox
The following variables will affect the current vehicle mass:
Overestimating the vehicle mass will give a power figure that is too high. Underestimating the vehicle mass will do the opposite.
DDRD takes into account aerodynamic drag when calculating engine performance. Vehicle drag co-efficient and frontal area are the parameters required to calculate power lost to aerodynamic drag. Whilst important for accurate power calculations, these vehicle characteristics are far less important to measurement accuracy than the vehicle mass. Aerodynamic drag is quite small in 2nd & 3rd gear and so inaccuracies in these figures will only result in a small (2 or 3 BHP) error in calculated power. If power tests are performed in higher gears e.g. 4th, 5th or 6th, then the importance of these values becomes much greater. In the absence of definitive data, use a frontal area of 2.2 sqm and a drag co-efficient of 0.35.
The ECU's rev limit is only relevant when calculating the maximum speed possible in each gear. It is not used for any other performance calculations. Unless your car's ECU has been modified, then simply select the rev limit matching the model of your car.
DDRD gives real world performance figures - plain and simple. There is no disputing performance figures that are calculated on the road, in the true driving environment. There are many variables that effect the results of power testing for both chassis (rolling road) and on road dyno testing. These include:
When testing on the road, you know that the above variables are all real world quantities encountered on the road. Only if the operator of the rolling road can reproduce all of these effects as seen on the road will the rolling road performance figures be close to those actually encountered on the road. Having said that, in order to get accurate results using a road dyno method, it must be setup correctly, though this is much easier to achieve.
Power Engineering assisted in the development of this product. Power runs of the development vehicle were taken on the rolling road. A figure of 227 wheel horse power was produced in 4th gear. Out on the road, using DDRD, figures of 222 & 233 horse power were produced in 2nd & 3rd gears respectively. From this test, it is clear that both methods of testing can produce very similar results. It is worth noting that Power Engineering have extremely powerful cooling fans on their rolling roads - these fans help to mimic the air flows seen on the road. They are so powerful that walking in front of these fans can make you lose your balance - it is worth checking the cooling equipment that is employed by your chosen rolling road test centre, since this can have a significant effect on results.
For various technical reasons, it is not possible to accurately calculate flywheel horsepower using using DDRD. All performance figures are quoted in wheel power & torque - the actual power seen at the wheels. Most rolling roads are able to calculate flywheel horsepower reasonably well - this is one reason why a visit to your local rolling road is worthwhile. Having said that, it is wheel horsepower that is relevant to the real world - this is the power that the vehicle is putting down onto the road. Just don't get flywheel and wheel power confused. If you get quoted two power figures, the wheel power is always the lower of the two.
Disclaimer & Safety Considerations
DDRD should only be used on private roads and test tracks. Under no circumstances should the product be used on the public highway or in any other situation where its use may break speed limits or contravene any laws. EcuTeK take no responsibility for inappropriate use of the product.
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