A Diesel engine is a heat engine. The only way to make more power in a diesel is to make more heat. More Heat is more power.
1. There are 3 major ways of tuning Diesel engines.
A. Common rail tuning
- Increases rail pressure by changing voltage to the fuel sensor, sometimes the turbo sensor. Quality units connect to the camshaft sensor to measure engine rpm as well.
- These systems increase fuel pressure sometimes dramatically; they work on earlier diesels ok but are less successful on later engines after 2008 that have pilot injection.
- Easy to remove and must be removed at service for the fuel pump calibration.
- Cheap price from $300 to $1200 but no need to spend more than $500 for one of these units.
- Can cause faulting and smoke if the cars fuel system is not in perfect condition, and many are not as filtration hasn’t really changed in 20 years, but fuel pressures have increased 10 fold.
- Critical to be set up correctly and custom installed, advanced units can be data logged which is by far the best.
- Most or all modern common rail engines from around 2008 have a pilot injection, when you raise fuel pressure the pilot injection (and pre injection in the case below) are affected, this is not good as the pilot injection (and pre injection) are very precise and should not be changed. Only the main injection should be increased. Earlier models that have no pilot injection are ok with common rail chips
- Poor resale value.
- Poor power gains compared to injection tuning or remapping
- Out dated technology now, there are far superior ways of tuning, these systems are about making easy money, not providing a quality result at any level….
B. Injector Tuning
- Provides total control over the length of the injection pulse to add fuel.
- Extremely accurate. Can control the fuel injector within 1;1 millionth of a second at every rpm and does not affect the pilot injection or pre injection at all, only the main injection is increased in length.
- A quality external tuning unit can be asked to reduce the tune if the engine or exhaust temp rises too much to protect the engine.
- Can control turbo boost and rail pressure as well for high power results.
- Can be switched off or removed easily, cannot be detected when turned off by.
- Cost effective, from $750 to $2500 depending on the engines fuel system and number of cylinders.
- Make excellent and reliable power, quality resin filled units will last the life of the vehicle. Can be tuned to individual engines easily and moved to the next vehicle.
- Quality units can be data logged to perfectly fit the engine they are to be installed on. This is the perfect solution and superior to any other method, it customizes the tune perfectly to the individual engine and takes into account all the variables that differ between the same engines.
- Quality units have very good resale value.
- Only a very specialized electronic control unit can tune an engine fitted with High Voltage Piezo fuel injectors.
- Can make as much power as the engine can deliver reliably and easily.
- Quality units can be supplied with several maps.
C. Computer Remapping
- Changes the software in the cars computer to add fuel
- Generally make good power and torque, but like all products, some a much better than others, some tuners are very good, some very bad, you need to trust the tuner.
- Detectable at dealership, Aftermarket warranty companies may check also.
- No resale value.
- Can be overwritten by a dealership software upgrade
- Most European dealerships will easily detect software changes.
- Many cars can be tuned directly through the OBD port
- Some times the computer must be removed from the car and opened to be tuned. You should be sure what you are getting.
- Usually very reliable if its been done well but beware, Many people ask for big power gains, you get what you ask for, it costs money to turn the car down if you get sick of the extreme tune…..
D. Chip tuning or Aftermarket Computer
- This technology is mostly used on extreme, high performance and modified petrol engines and is a good solution for that.
- Not commonly used on modern diesels engine engines and should be avoided. There are much better solutions available unless it’s a highly modified race engine
Tractor engines are the hardest working engines, even harder than trucks, they never get a break like a truck going down a hill or working on the flat. A tractor can work at 100% duty cycle for hours at a time. They should always be tuned with a dyno for this reason. If a dyno is not available a plug in device should be used.
The reason based on a 20% power gain wanted. So 100hp changed to 120hp
- Plug in units only work with the added power, not the total power. So a 10% mistake will make 2hp of unwanted power. (10% of the added 20hp = 2hp)
- Changing the computer software works with the total power, not the added power. So a 10% mistake will add 12hp of unwanted power. (10% of 120hp = 12hp)
- When tuned with a dyno, the power addition can be checked. It’s very important with tractor tuning to use a dyno always.
Truck tuning is also very complicated, Truck dyno’s are very expensive and very few tuning companies in the world have them. However most trucks with manual gearboxes can be used to dyno themselves. For example a truck can drive up a hill loaded before and after the tune. If the truck is 1 gear higher after the tune, this equates to approx 60Hp. So its important to have a tuneable device that can be adjusted to make the correct power. 2 gears higher may well cause the engine to have a short life.
- Some trucks are best with changing the computer software
- Many work very well with plug in or wire in tuners.
- Neither is better than the othger
4. Turbo Boost
Increasing Turbo boost in most cases is very good. The engine does not necessarily have plenty of air, Many modern diesels run quite rich, 19:1 or less. Diesels don’t run rich or lean but they do make soot when the air fuel ratio gets below around 17:1 and this soot is hard on turbos, egr and can clog intake manifolds via the egr. added boost can bring the air fuel ratio of a tuned engine back to above 20:1
You should know your tuner, Any tuning solution that only adds fuel in passenger diesel engines should be avoided unless, its its a very modern multi turbo engine, or you know its a lean from factory engine.
5. Inter-coolers & Exhaust
larger inter-coolers will dramatically increase performance, cooler air will carry the fuel particles better than warm air, The cooler air will raise the air fuel ratio, there is no down side what so ever.
A larger exhaust will almost always help a diesel engine, by better breathing and removing heat from the top of the engine and turbo, there is usually 10% gain to be had, 15% if the car has been tuned.
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