The deepening of today is a focussed on a (MY 2013) Porsche 911 (991) 3800 GT3 equipped with a Bosch MED17.1.11. ECU supported by a 3.8L engine with direct fuel injection (DFI), 470HP at 8250 rpm and a torque of 440Nm at 6250 rpm.

The engine is based on the model equipped on the 991 Carrera S, but shares with it only some parts. All the other components, also important parts like valves and crankshaft, are customized and developed specifically for the 991 GT3.

For example, the 991 GT3 engine supports rods in titanium directly linked to the piston, allowing the engine to reach 9.000 rpm! The dual clutch transmission is another peculiarity developed only for the 991 GT3 engine, based on the manual transmissions equipped on race cars.

 

>> A view on all the 58 maps available and that can be tuned for this driver.

 

 

And now let’s take some maps as example, to go more in details about the modifications and editing we may do.

 

>> Injection - Lambda

Requested Lambda

It allows you to quit switch from the Closed Loop function (it happens when the injection is set to keep always lambda =1), so to increase the amount of oil in the carburetion either at high revs or at high speed.

 

Lambda Protezione Componenti

>> Injection - Lambda

>> Requested lambda

It allows you to quit switch from the Closed Loop function (it happens when the injection is set to keep always lambda =1), so to increase the amount of oil in the carburetion either at high revs or at high speed.

• Table View

• 2D View

 

>> Air Control  - Throttle Valve

Throttle Valve and its operating angle

It allows you to set the operating angle of the throttle valve and to apply a linearizing strategy to the curve of this map (eliminating “steps” and making it smoother) so to have less sudden and rough responses from the engine. To do that, you should use the 3D view of ECM.

• Throttle Valve operating angle - original

 

•  Throttle valve operating angle - modified - 3D view

 

•  Throttle valve operating angle - modified (II example) - 3D view

 

Mass air flow through the throttle valve

It allows you to re-set the measurements taken by the MAF or, in case it has to be changed, to make a re-calibration of the parameters of the ECU.

• Table view

 

Details about the MAF

The MAF sensor (Mass Air Flow) accurately determines the mass flow rate of intake air [kg/h] taken right after the air filter, using a sensor called «heated wire»: a very thin metallic wire is heated electrically and then immersed in the air flow; it will become colder proportionally to the amount of the air passing through. The «heated film» works more or less in the same way, the wire is substituted with a film. In the MAF there is also a thermometer so no installation of a new sensor is required as instead in the IAT (Intake Air Temperature).

MAF offers a good accuracy in every situation but it is very delicate (the diameter of the wire is only some micron…) and tends to get dirty easily making inaccurate readings. A wrong detection of the intake air may cause many problems because the carburetion cannot be accurate: often one of the first thing to do before tuning the files of the ECU is to change the original standard sensor with a new one; this should be done also because the MAF is designed for a certain amount of measurable air and so, if you want to modify and increase the capacity of the intake air, you need also a «potentiated» MAF, otherwise you risk to have a poor mixture at high revs.

 

>> Rail

Rail Pressure

This map manages the fuel pressure inside the common rail itself so to have a more efficient combustion reading real values (MPa) without bad surprises.

 

 

>> Engine Torque

Requested torque in standard condition

It manages the torque requested by the driver with the accelerator pedal. This car has an automatic 7 gear transmission (PDK), so it’s possible to manage the engine torque for each single gear (7 gears + neutral + reverse).

• Table view

 

Details on PDK transmissions

PDK transmissions are used to shift gear in the fastest way possible without interrupting torque distribution to the wheels, the values of acceleration will be optimised saving on consumption too.

This is new for 911 models – In the PDK Manual Mode, the transmission has the possibility to be set like in race cars and 911 GT3 model: a small touch backwards to shift gear, one forwards to shift into the lower gear. Like being in the track!

From the first to the sixth gear the transmission is in sport mode. The highest speed is reached in the sixth gear. The seventh gear is instead focussed on fuel saving.

PDK consists in two integrated shifts in only one box. This double clutch system links the two shifts to the engine with two concentric primary shafts. The engine torque is constantly applied using only one transmission and a clutch at a time, the following gear is already ready in the second transmission. When the gear is shifted, while in the transmission the first clutch is closed, the second is open at the same time. The gear shift becomes a matter of milliseconds.

Max Torque for each gear

It’s 1000 Nm because the transmission is automatic so the maximum torque available for each gear is limited only by the TCU (trasmission control unit) PDK.

• Table View

 

Best engine torque

This engine is manufactured in many versions (some also with mechanical changes) so in this case you won’t be able to find the 100% of the available torque. Increasing the values to 100% in the last column (corrisponding to 100% of air), it’s possible to reach the best performance for this kind of engine; it’s also possible to linearize the toque supply using the 3D view map like we did with the throttle map before.

Best original torque

• 3D View

 

 

 Best modified engine torque

• 3D View

 >> Advance

We implemented either the map managing the standard advance either the one for the best advance. It’s important to make a distinction between the two maps because the best advance one shows the limit you reach during the map tuning, while the standard advance is used during the normal vehicle operation.

• 2D View

 

• Table view