Rolling Road Bolton

Monaro 330bhp

Dyno Setup and Checking of a Newly Converted LPG Vauxhall Astra


Diesel tuning boxes or ‘black boxes’, as they are sometimes known, have been around since the mid nineties when diesel engines started using computerised electronic control units (ECUs) to precisely control fuel delivery. Tuning boxes are an alternative to a vehicle ECU remap and consist of a small electronic box which is either hard-wired or plugged into the vehicle’s fuel system circuitry.

Mechanical Throttle Linkage

Typical Mechanical Linkage

A simple test that can be performed on most vehicles, to check if a black box is a possible option, is to check for the presence of an electronic throttle. By depressing the accelerator pedal with the ignition off, while at the same time observing the engine bay for any movement of linkages or cables connected to the throttle body, it is possible to determine if the throttle control is mechanical or electronic. As a general rule, if there is any throttle body movement, the throttle is cable controlled. If not, then it’s likely the throttle is electronically controlled and therefore a tuning box can be fitted in most cases.

How a Diesel Tuning Box Works
Electronic Throttle Body

An Electronic Throttle Body

Unlike an ECU re-map, tuning boxes normally increase the engine’s fuel quantity only and in most instances do not increase the engine’s turbo boost pressure. However, due to the way the diesel engine works, each combustion usually takes place in the presence of excess oxygen, meaning that, under most engine speed and load conditions, there’s oxygen available to burn any extra fuel that may be introduced.

Diesel is a very difficult and slow fuel to burn and that’s why diesel engines tend to smoke excessively under hard and fast driving conditions. Adding more diesel into the cylinders does indeed create more power but there comes a point where the extra power also produces extra smoke, especially at high loads and higher engine speeds.

First and Second Generation Tuning Boxes

Van Aaken Smartbox There are many different makes and brands of Tuning Boxes available to fit most vehicles. Some of the first generation types are analogue and simply use a resistor to alter ECU signal voltages. The more expensive second generation boxes are normally digital and some even claim to be fully mappable (which can’t be true unless it monitors engine speed, fuel quantity and engine load).

Gerd Van Aaken at CRD Performance

Gerd Van Aaken at CRD Performance

The Pioneer of one of the first tuning boxes is Gerd Van Aaken, previously of Van Aaken Developments, who is also the developer of the Smart Box, a second generation tuning box now marketed by Cybrand UK. Gerd’s expert advice and technical input has also been invaluable to us during development of our own third generation tuning box. Other popular brand names include The Original Tuning Box, Tunit, Chip Express, BHP Plus Speedhawk, DTUK CRD2 and CRD-T, Synergy, Spider, TDI Tuning, Racechip, TD Performance, to name but a few.

Tuning boxes are sometimes criticised because of how they work; most boxes fool the vehicle’s ECU into increasing diesel fuel rail pressure, with the exception of Steinbaur, whose tuning boxes electronically extend injector opening times, both allowing an increase in fuel quantity. These methods are not ideal since neither make adjustments in the same way a proper ECU re-map does, by taking reference from both engine speed and load.

At CRD Performance, Bolton, we can supply and fit any make and type of tuning box or, if a customer already has a tuning box, we’re more than happy to install that too. The cost of installation will largely depend on installation complexity and time, which in turn will depend on vehicle make, the type of tuning box, ease of installation and also whether or not a rolling road dyno setup is required.

Third Generation Tuning Box

Probably the most advanced third generation diesel tuning box available is The Select-A-Map; this common rail diesel control unit has been developed in-house, of which Eddie Zyla is the Technical Director and a major shareholder. The main difference between the Select-A-Map unit and previous generation tuning boxes is the way in which it controls the diesel by creating a 3D map, using engine speed and load, replicating a proper ECU re-map.

BMW 5 Series GT F07 530d - Select-A-Map Installation BMW 5 Series GT F07 530d
The Select-A-Map installed on a BMW 5 Series GT F07 330d, with its proud owner (right).

The vehicle pictured utilises the later N57 engine, which can also be found in the BMW 3 Series E90/E91/E92/E93 325d/330d/330xd, the BMW 5 Series F10/F11 530d, the BMW X5 E70 xDrive30d, the BMW X6 E71 xDrive30d, the BMW X3 F25 X3 xDrive30d, the BMW 7 Series F01 740d/740d xDrive, the BMW M550d xDrive and numerous other vehicles. For many vehicles such these, the Select-A-Map presents a good alternative to a remap, especially for vehicles where a remap is impractical or problematic.

Technical Information

For those of you who are technically minded and would like to know more about how the system works, click the link below to either view or download the full operater manual of the Diesel Control ECU.

Diesel Control ECU – Operator Manual

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View Manual Online
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Download Manual
(PDF format – 1,950 KB)

Select-A-Map Retail Brochure
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View Brochure Online
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Download Brochure
(PDF format – 1,562 KB)
Printer-friendly version
(PDF format – 923 KB)

There are many discussions on internet forums centred on what’s best; an ECU re-map or a diesel tuning box. As a supplier of both tuning boxes and ECU remaps, we have little to gain by arguing for or against either technology, preferring instead that the customer makes an informed decision that best suits his/her application and budget.

Customers are welcome to contact us to discuss the options available.

Price Guide

First generation tuning box (from) £85.00 +VAT

Second generation tuning box (from) £295.00 +VAT

Fitting cost between 1 & 2 hours (approx) £70.00 – £140.00 +VAT

Select-A-Map (from) £499.00 +VAT

Rolling Road Dyno Charge (from) £40.00 +VAT

Rolling Road Dyno

Measuring the Power

CRD Performance, Bolton, is one of a few specialist UK garages to own a rolling road (also known as a dyno’ or chassis dynamometer)

The 2WD dyno’ is frequently used for both diagnostic purposes and to measure calculated engine brake horse power (BHP) and torque.

There are two methods used to measure BHP and torque: A braked dyno’ or, the preferred modern method, an inertia dyno’. The dyno’ at CRD Performance is capable of both methods.

Braked Dyno

Braked DynoHaving ‘settled’ the vehicle and strapped it to the dyno’ the car can now be driven on the rollers in any gear and up to 125mph.

The operator chooses at which road speed or engine speed to apply a braking force to the rollers using the inbuilt eddy current brake.

Fault Diagnosis

If diagnosing a running fault at motorway speeds, for example, the rollers can be restricted to 70mph and, no matter how hard the operator accelerates, the rollers will not exceed 70mph. This fixed speed method can be used to carry out diagnostic tests and measurements to the ignition and fuel systems at various engine loads. In this mode we would normally observe exhaust gases, ignition coil output, fuel pressure and flow and even turbo boost pressure. Being able to choose any speed and engine load also allows us to to calibrate an LPG system or remap (tune) the engine’s power using, for example, the Dastek Unichip.

Estimating BHP

The more the operator presses the accelerator pedal or makes improvements to the engine power, the greater the BHP displayed on the dyno’s display panel. However, using a braked dyno’ for BHP measurements only displays the power at the wheels, not the power at the engine’s flywheel. Also, while a braked dyno’ is great for diagnostic work, mapping and before/after comparison testing, it is not suitable for accurately testing the vehicle’s BHP.

If, for example, a braked dyno’ were to be used to check the maximum BHP, the car would be rolled in the most ‘straight-through’ gear (normally 4th) at the required engine RPM. Let’s say max BHP is developed at 6500 RPM – then in 4th gear this may equate to 100mph, which the operator would find by gently driving the car up to 6500 RPM without locking the rollers.

Having now set the rollers not to exceed 100mph the vehicle is driven through the gears gently into 4th gear until 6500 RPM is reached and the braking resistance of the rollers felt. Now the operator can accelerate ‘flat out’ with the power at the wheels driving into the locked rollers, which causes a strain gauge attached to the torque bridge of the Dyno’ to move; the greater the power, the greater the strain gauge movement and higher the BHP on the display.

Now the BHP is known at the wheels we can estimate the flywheel BHP; Any losses, including transmission and tyre friction losses, have to be taken in to account. Typically, it is generally accepted, that front wheel drive cars lose around 20% through their transmission and tyres, while up to 25% loss is normal for rear wheel drive vehicles. These figures are only a guide since some well engineered vehicles, Porsche for example, are often claimed to lose only about 15%. Other factors effecting losses include non standard wheels and tyres, tyre pressures and adverse geometry (such as excessive negative camber or toe in/out).

Inertia Dyno

Rolling RoadEven though our Sun Ram X11 rolling road was originally designed to be a 300BHP braked dyno’, it has since been modified and upgraded to enable it to also work as an inertia dyno’. using the TAT software system, and is now capable of measuring up to 500BHP at up to 160mph.

The inertia method of measuring BHP does not rely, in most cases, on the eddy current brake to load the rollers. The TAT system, during installation, is configured to match the type of rolling road it is to be used with, so it therefore knows the mass of the rollers and can make its calculations accordingly.

After initial programming and calibration all the operator needs to do is drive the vehicle at 60pmh in any gear he chooses, (often top gear) and let the TAT dyno’ software know what the engine RPM is at 60 mph. The system automatically measures the workshop’s air temperature and takes a barometric pressure reading so that BHP calculation compensations can be made, be it a cold, damp day or a hot, dry day.

The operator would initially strap the car down, position the cooling fan next to the radiator and perform 2 or 3 runs to warm the tyres and transmission. During the power run it is normal to set off slowly in 1st gear to approx’ 2000 rpm, then 3rd gear to 2000 rpm, select top gear and then ‘floor’ the throttle and accelerate to the engines max’ RPM or rev-limiter. At max RPM or rev-limit the clutch is pressed (if a manual transmission) and neutral selected, then the operator waits while the vehicle coasts to a standstill, during which time the transmission losses are measured.

Rolling RoadSince the TAT system knows the engine RPM at 60mph and the mass of the rollers, it monitors the acceleration rate and deceleration rate of the rollers, from which it calculates engine torque and BHP at the flywheel. This method of calculation even allows for excessive transmission losses due to tyre temperature change during several repeat runs or even the vehicle being strapped down too tight.

We have used this inertia method hundreds of times and it never ceases to amaze us how accurate it is. We have frequently had customers come to us for power runs, claiming some wonderful exaggerated unrealistic power figures their vehicles have produced on someone else’s dyno’ – all I can say to these is that our dyno’ has done very little work from new and often measures non-modified standard cars whilst in our workshop of either an LPG conversion or to have a Superchip and the BHP measurements we see are very believable.

I did mention earlier that the inertia method does not use the eddy current brake most of the time, now let me explain the exception: When testing high-powered turbocharged vehicles it is essential that the turbo is made to work so that boost is achieved. Without any dyno’ braking the run could be over in just a few seconds and therefore maximum boost may not be achieved. The TAT system allows the operator to select a small and linear amount of roller braking throughout the whole run, to enable full boost and engine power to be realised. The amount of eddy current braking is electronically fed into the TAT software during the power run but is then switched off by the operator during deceleration to allow correct measurement of transmission losses.


You will be asked to sign a disclaimer prior to your vehicle going onto the rolling road.