The Smart Money

Diesel engine performance modules deliver big power gains, but what makes them tick, and are they alt the same?

(4WD CUSTOM GUIDE NO.41 Page.67)

WORDS BY COLIN BROAD. PHOTOGRAPHY BY DAN MACKENZIE AND 4WD ACTION

Back in the day — and we’re not talking about that long ago either — diesel tuning was all about adjusting the settings on the fuel pump, and playing with the intake and exhaust systems to help the engine breathe easier at the same time. These days, the modern diesel is monitored, adjusted and timed based on a series of sensors, and the readings that they send back to the Electronic Control Unit (ECU). If you have an electronically controlled fuel. pump fitted to your modern CRD or late ‘90s-onwards diesel engine, then a diesel engine chip may be just what you need. Gone are the good ol’ days when an old oiler needed to be physically altered in an attempt to get a similar power gain.

There’s no black magic involved when it comes to diesel engine chips, though getting it wrong can result ¡n a very expensive repair bill. A diesel engine chip essentially adjusts the fuel timing as well as setting new parameters for the airflow sensors and other meters. What this means is that it has to communicate with your entire engine management system to work properly.

Most modules are simple plug and play units, while others need a little more effort to install. They can be installed as a DIY project, or if you are time poor like a lot of us, then a technician can usually install the module in under 30 minutes. Either way, it’s generally money well spent. Let’s take a look at what goes into the design, engineering and tuning of a diesel engine performance chip so that your engine can unleash some of that untapped potential.

THESE CHIPS OFFER A BIG REWARD

FOR LITTLE OUTLAY

• 1 Diesels do two things: generate power and generate heat. By adding fuel alone, the air to fuel ratio becomes heavily biased towards combustion and in the absence of enough air to even out the ratio, excess heat is generated without any extra gain ¡n power. Adding more fuel is the backbone of the diesel chip theory, though having a good air supply is just as important.
• 2 Simply pumping in a greater volume of fuel at the same pressure means that the injection timing has to be readjusted to correspond with the correct position of the piston. The reason is that as fuel quantity increases, the time taken to inject it also increases. Chip manufacturers spend a considerable amount of time ensuring that the fuel pump pulse and delivery are accurately timed, and with today’s relatively high-revving modern diesel engines, this fuel timing is critical. Too early and it tarts to burn before the piston is ¡n the optimum position and wilt actually work against the piston’s direction of travel. Too Late and the piston wilt already be too far down its powerstroke and miss out on the combustion bang to help power ¡t. It'll also result ¡n unburnt fuel mix flowing out of the cylinder. Exhaust gas emissions can provide a good indication of how welt the fuel is burning. The richer the exhaust gas emissions, the Less fuel is burning properly.
• 3 The engine’s ECU is responsible for a number of settings to determine how much power the engine produces. Aftermarket performance modules adjust these settings to extract more power from the engine. These include common-rail fuel pressure (the higher the pressure, the more fuel is injected with each injector pulse), how Long the injectors are held open for, and how many times in one cycle that it injects. Chips can also adjust timing (see the previous caption), and the vehicle’s M.A.PI (Manifold Absolute Pressure) sensor that calculates the air density (and hence volume) within the manifold to adjust the fuel Levels. In modern vehicles, they can also monitor engine Loading and adjust fuel delivery if they sense the potential for damage (for example, too high an exhaust gas temperature)
• 4 Diesel chips have been around since the introduction of electronically control led fuel systems. Initially, diesel engines only used an electronically controlled fuel pump, but with controlled injection and common-rail systems, the number of adjustments available to tuners has grown. When a company develops a performance module for a new engine, the development starts with a known number of adjustments and parameters from similar engines. These are then tested thoroughly to ensure the right combination of power and reliability. For a new system, anywhere up to 12 months of testing ¡s to be expected, though if it is an update to an existing engine or system, it can be done in as quick as a week.
• 5 Traditionally, there's a good 10 years between major model changes, so most diesel chips wilt be interchange able with previous models with some minor adjustments to the internal tune. Major changes that require a completely new design come around about the fourth model change, and normally in conjunction with a major change to the electronic systems
• 6 “We spread our development efforts between the UK, Europe and Australia to keep up with a changing market,” said Roo Systems's Glenn Hadden when we caught up with him. “As for field testing, we employ the services of companies or take feedback from customers who are currently using our modules, testing them in the real world with real-world results. The chips work straight from the box. We Listen to our customers to develop the modules even further and find that maximum safe performance Level.”
• 7 Dynos are critical when fine tuning a module. These do not Lie, and the figures displayed are the best way to measure the exact out put of the chip. Improvements or adjustments are displayed, and any adverse effects such as high exhaust temperatures can be determined. “Dynos are an important tool in the whole development process,” says Berrima Diesel’s Andrew Leimroth. “They’re the most accurate toot that you can use to get instantaneous and consistent feedback, as each dyno run is identical. This ¡s why we have spent the money and now own two out of three of the world’s most advanced dynos, purely for this urpose.”
• 8 As a general rule, a 25% increase in power won’t affect the life of your engine, though your current engine condition wilt obviously play a big part in how Long it Lasts. Torque Increases of 15% are reasonable, and when matched with a good exhaust system, the overall gain is typically around 35% in total. To get the most out of your exhaust and diesel chip, dyno tuning is essential
• 9 Quality of the tune is critical. If performed incorrectly, even a tune that ¡s designed to give a 10 to 15% increase could actually be detrimental. Diesel chips may be supplied with a fixed set of parameters, or they might have a selectable range of settings with different parameters and performance gains. Not all chips are adjustable, and this is dependent on the architecture used inside.
• 10 Air delivery ¡nto, and exit from, the engine is the second consideration after fuel. Accessories such as aftermarket or high flow turbos and air filters, Larger mandrel bent exhausts and dump pipes, all help with power gains. If more air can be fed into and out of the engine with fewer interruptions, then more power wilt be developed. However, less power should be expected if this airflow is restricted ¡n any way. During development, manufacturers will try standard combinations, right through to a fully modified and tuned combination of components. “I could List several hundred vehicles from all around the world that use one of our chips,” says John Stillitano from NAFTA Performance. We have designed and tested every single one of them, so we’re certain that they all work.”
• 11 There are several brands on the market each with different claimed performance figures. Some are set and forget, white others are fitted with an adjuster so that you can pick which setting you prefer. Bear in mind, though, if you have more power available, you're most Likely going to play with it. Though theoretical, fuel gains are a given, it all comes down to how much you flex your right foot!
• 12 lt pays to do your research before you buy. A dyno graph is good, but first-hand experiences are better. Irrespective of which module you chose or even who makes it, choose a reputable brand with plenty of testing behind them. That way you won’t run the risk of blowing up that nice expensive engine!