Modern Diesel Engines
Modern diesel engines have come a long way from the old oil burners of years gone by. They now have very well designed and tested components. Things like air intakes, cylinder heads, camshafts, combustion chambers and exhaust systems are all made to the most efficient levels the manufacturer can make. This is how they achieve great power levels from small engines.
In fact many of the modifications race teams were doing twenty years ago to high performance petrol engines have made their way into the modern diesel engine. Bosch has developed a fuel injection system that is the envy of any system on a petrol engine, the Common Rail Direct injection fuel system. It has made the diesel engine what it is today.
These engines are the very best that the manufacturers can build. They have all the good parts, good design- they just don’t have enough fuel! They are running lean to meet the euro III, IV & V emission requirements.
This is where DTP Ultimate chips come in. Our tuning chip is designed and built in the UK to work with the Bosch (common rail) system. We add the fuel that the factory can’t add, and they can’t add it for two reasons. First, the Euro emission laws are why they don’t add more fuel to generate more heat (the only thing that will make power in a diesel engine), and the second is climate. All these engines must work in extreme cold where fuel becomes thick and hard to pump, this is why fuel pressure is set lower than it could be. Not a problem in the Philippines, so let’s add some fuel pressure (about 5% more) and have the power the Alaskan’s can’t have.
It must be noted that we don’t add overall pressure, We can only do that by installing a larger fuel pump. We add pressure for a specific RPM. For example at 2000 RPM we increase pressure by 5%, and the same for 2100 RPM, and 2200 RPM and so on. The maximum pressure will not change as we electronically turn the unit off when it reaches full pressure.
This is where the digital DTP Ultimate chip comes in, the engine now has everything and the added fuel pressure we put into the engine does several things. A finer spray of fuel burns much more efficiently, makes more heat and builds more pressure on the piston which generates more power. More power means you drive with a lesser throttle opening and less fuel used. We have installed units on large trucks towing large trailers and achieved a 12% fuel saving as measured by GPS.
But we don’t just add 5% fuel pressure. The unit also makes the fuel pump, pump more volume of fuel. This has a knock on effect in that the added volume of fuel through the Common Rail triggers the computer to add a little pulse width to the injector cycle. The Computer calculates the injection pulse based on the fuel volume being pumped. BUT as it’s the factory computer that’s adding the injection pulse, it is still within the spec that the piston is designed for. (see notes below on the piston design). This is where the additional power comes from and mid-range torque comes from, the reduction in consumption comes from the increased pressure.
For some vehicles we have units that connect to the fuel and turbo pressure sensors on the engine. This allows the turbo to blow an additional 4-5 PSI of boost. This is enough to make a nice difference and keep the exhaust a little cooler, but not enough to overload the factory turbo.
You will get a 7-14% fuel saving on cars and SUV’S from the added efficiency, lots more smooth torque and quite often the gear shifts are better as well. Diesel engines are very short of revs compared with petrol so the gear shift has to be perfectly placed, with more power being put on the transmission we often find the car makes its mind up better and the shifts seem to be improved.
Of course, the engine has its own protection system. We simply cannot add more fuel or air pressure than the factory allows. There are pressure sensors on the fuel and air intake of all common rail diesel engines. (Remember, all common rail systems are built by Bosch, it’s their technology much like Windows belongs to Microsoft) If those sensor’s report a pressure higher than the factory has set as a safe maximum, the car’s ECU will shut the engine down to limp mode.
Ok so here are a couple of very important points to recap
Firstly, the factory designs the combustion chamber shape in the piston, to work in conjunction with the diesel injection timing. For example the piston below may need the injection between top dead center (+0) and 6 degrees past top dead center (+6) and a different piston may need +1 to +8. This is why we (after years of playing with engines) disagree with changing the injection timing by remapping the computer. Unless each map or chip is adjusted for each engine specifically, then you have the ability to generate a lot of heat in the piston. The injector needs to spray the fuel perfectly into the piston cup.
At DTP Ultimate chips we NEVER change the start point of the injection timing. That’s great in a race engine, not good for extended duty cycle.
Secondly, the factory turbo is designed to blow a lot of excess air through the engine to lower or dilute the exhaust emissions. The more spare air in the emission test, the lower the emission result. This is why we can fuel up an engine without the need to add extra boost. With our chip you will expect an extra pound due to the added efficiency.
We hear our competition that remap, talking about the fact that ‘only they can tune a diesel engine, they must change all the computer settings and rewrite the whole program. We already talked about the timings related to Combustion Chamber, there are no spark plugs or spark timing, the turbo already blows spare air and the air fuel ratio doesn’t matter as a diesel will run from 12:1 to 50:1 quite happily. There is no rich or lean in a diesel, you are just burning oil and when the oil is all burnt, the fire goes out whether or not all the air is burnt. So what do they do – they add fuel pressure and play with injection timing outside of what the piston is designed for.