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Diesel Tuning: A Guide to Diesel Engines

A diesel engine uses heat compression to initiate the process of burning the fuel previously injected into the combustion chamber. It differs from spark-ignition engines that run off petrol gasoline, which are commonly found in standard automobiles. The diesel engine ranks as having the highest thermal efficiency of any standard internal or external combustion engines, because of its exceedingly high compression ratio. Diesel engines come equipped in two different models, including the two-stroke and four-stroke. In 1893, Rudolf Diesel built the engine as a replacement for stationary steam engines; the diesel engine became the definitive answer for commercial transportation vessels, such as locomotives, submarines, ships, trucks, heavy equipment, and manufacturing plants. Automobile manufacturers began to slowly introduce diesel engines in a few on-road and off-road vehicles, and eventually led to the rapid selling of non-commercial cars across the United States. As of 2007, nearly half of all new car sales have diesel equipped engines in Europe.

The first diesel engine prototype used injected fuel with the assistance of compressed air to atomize the fuel before forcing it into the engine through a built-in nozzle. The nozzle opening had a pin valve that was closed by a camshaft, which started the flow injection process, also known as an air-blast injection. This early model used minimal power compared to the efficiency and net power output of modern diesel engines. Today's diesel engines increase the fuel to high pressures through a series of mechanical pumps that lead to the combustion chamber by pressure sensitive injectors. Direct injected diesel engines use injectors to spray fuel through four to twelve different orifices in its nozzle. The earliest air injection diesel engines always had top notch combustion without the extreme increase in pressure during the combustible phase. Researchers have taken the effort to design efficient air injectors that will reduce the overall pollution emissions in today's automobiles.

Diesel engines employ a mechanical or electrical governor, a vital component that regulates the idling and maximum speed of the engine's fuel delivery rate. Without a governor, diesel engines exceed their speed capacity, which sets the self-destructive process in motion. All mechanical governor fuel injection systems utilize the diesel engine's gear train, which consists of a combination of springs and weights that control fuel delivery according to the automobile's load and speed specifications. Diesel engines equipped with an electronic governor utilize an electronic control module (ECM), a device that receives an engine's speed signal and other operating controls. Altering the advancement and delay of the start injection results in reduced fuel efficiency, exhaust smoke, and elevated engine noise.

There are many advantages of owning a diesel-powered engine over other internal combustion engines. For instance, diesel engines burn less fuel than petrol-based engines exerting the same force, because of the engine's high temperature combustion and expansion rate. In addition, a diesel engine lasts about twice as long as petrol-based engines due to the fuel's lubrication properties. Diesel fuel has a safer composition than petrol, and can be applied in various ways. Diesel engines generate far less heat in their cooling and exhaust processes. They accept super and turbo charging pressure without setting natural limitations, and only become restrained by the engine's internal components. Diesel engines also emit far less monoxide content than their counterparts.

Despite its advantages, diesel engine technology certainly has its pitfalls. In cold weather, high-speed diesel engines may prove difficult to ignite, because the cylinder block and cylinder head absorb the heat compression. Diesel fuel also becomes prone to waxing and gelling in cold weather. In addition, diesel engines tend to create loud noise, also known as diesel clatter, diesel knock, and diesel nailing. Diesel nailing is caused by the internal combustion process that occurs from the ignition started from the heat compression.

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What others are saying...

“I was a sceptic at first, then after reading the experiences others had been through I decided to give it a go. I bought a new 1.7 CRDI Sportage, not the 2ltr purely for better fuel figures. Whilst this engine pulls very well in standard form, and was returning 44-45mpg even during the first 500 miles I had to go down the CHIP Express route. Well, there is absolutely no point in forking out the extra 2 grand for the 2 litre model when you can get the 1.7 and spend much less to get 2 litre power figures. Excuse the cliché’s, but this car is transformed and by a big margin too. From what I can remember about my 2 litre test drive, my 1.7 now pulls better than the 2 litre version. The low-down grunt is remarkable and pulls like the proverbial train. Fitting took minutes and was effortless, the box was kept on factory settings, I feel there is no need to mess with it. Needless to say I am now a very happy boy and would without question take this route again. I would recommend this to any diesel Sportage owner. Many, many thanks for a remarkable product and a customer service that is rare in this country!”


Ron from Thetford

Kia Sportage MK3 1.7 CRDI 116

“Be assured, this is NO gimmick. Arrived yesterday (less then 24 hours after the order was placed) and fitted today. The fitting was easy especially with the photos and instructions sent with the chip. The first thing I noticed was the responsiveness of the engine from a standing start, no more lag. I then went on a 30 minute drive both motorway and sideroads and my average fuel consumption went UP from 33.3mpg to 38.7mpg. My motorway speed varied from 60 to 85mph and the sideroads from zero to 40mph. I am so pleased with the whole result. This is worth every single penny paid. Thank you!”


Edwin from Bridgend

Ford Kuga MK2 2.0 TDCi 163

“I have a 2015 Mercedes E250 CDI Cabriolet and recently fitted the chip. It took minutes to fit the chip itself and a further few mins of fettling to find the best place to stow the item, all in all a very easy solution. I bought the chip for the extra performance, more torque than power, as opposed to economy gains, and it has delivered it in spades. I took my car out for spin prior to fitting then again on the same road post fitting and I could feel the difference instantly and everywhere. I highly recommend this product for the grin factor, the economy gains will come as a result of the chip which to me is just a bonus.”


Leigh from Taunton

Mercedes E-Class W212 E250 CDI BlueTEC Facelift 204

“A good product and a good service deserves recognition: I fitted a CHIP Express unit to my Insignia. What an amazing bit of kit! My fuel economy and performance went way up and with the mileage I do was a Godsend! On a run to Aberdeen from Hull I returned an average of 62 MPG and I drive quite energetically! I've just taken up the trade in offer and saved a few quid on a new system. The Vauxhall has now gone with 125,000 trouble free miles and I have changed car to a Volvo S60 D3. I'm looking forward to fitting the Chip Express unit and reaping the rewards, thanks guys!”


Frazer from Skirlaugh

Vauxhall Insignia MK1 2.0 CDTI ecoFLEX 130

“May I congratulate you on this diesel tuning product as it has made a noticeable difference to my Land Rover Discovery. I have tried other diesel tuning boxes for my previous vehicles (Kia Sorento, Peugeot 206 and Vauxhall Vectra)... and they all produced slight engine stuttering under certain load conditions. The CHIP Express system does not show any evidence of this and is equal to the likes of an ECU remap (which I have also had done before) for smoothness and noticeable power gains. This would be the only diesel tuning product I would recommend.”


James from Callington

Land Rover Discovery (3) 2.7 TDV6 190

“As do many, I took the 'if it sounds too good to be true, it probably is' approach to performance chips. But CHIP Express were recommended by an impeccable source who had had experience with their product on my model of car - a Citroën C6 with the 2.7 HDi twin turbo diesel. Following a first rate response to a query, the product has delivered in spades. Ten days and more than 1000 miles of mixed town, country, low and high speed driving later I am certainly getting more than 10% more from a gallon, and probably 15%, and the performance is markedly better. Low speed response is immediate and has eradicated what I took to be baked-in lag in a big automatic turbo diesel, and mid-range acceleration is silky smooth, including up inclines. A very good car has been turned into the excellent car I had hoped for all along.”


Simon from Ketteringham

Citroen C6 2.7 HDi 204