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Old 19th March 2014, 03:34 PM   #1 (permalink)
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Post EcuTek RaceROM Phase 4 Rolling Launch Explained

Tobin @ Ecutek posted this on the other forum. Its been going down really well



EcuTek are all about pushing the boundaries of what is possible with the stock ECU and our Rolling Launch feature is no exception. Usually found on stand alone ECUs, EcuTek have engineered a solution that works with the stock ECU and doesn’t require any application of the brakes. It operates using the cruise control and is quick, simple and very effective at launching great big grins on the faces of anyone who has used it or experienced it. Let’s be clear though, this feature is not just for Roll Racing. It is awesome fun out on the open road - provided you use it responsibly of course!

The RaceROM Rolling Launch (RRRL) feature allows us to increase airflow, increase turbo speed and therefore build positive boost pressure whilst maintaining a constant vehicle speed. This is achieved using a clever closed loop Ignition Timing strategy that will control the Ignition Retard amount until the target manifold pressure (boost pressure) is achieved. This unique EcuTek feature makes Roll Racing possible with the factory GTR ECU.

Some Engine ECU and Transmission ECU log file screen shots below show the 3 different stages to the RRRL feature :

Step 1 – Preparing for RRLC mode
This stage is simply driving the vehicle with cruise control enabled. Turn ON the cruise control. Set your cruise speed as you would normally do. The vehicle is now in a controlled, steady state with no additional load placed on the engine or drive train.

The engine torque is around 30 to 60 NM depending on RPM, vehicle speed and other load factors like wind, road gradients and vehicle weight. Inlet manifold boost pressure is in vacuum at around -0.5bar (light load condition). Ignition Timing is around 40 deg



Step 2 - Entering the RRLC mode
Building boost and getting ready for a rolling launch – this stage is engaged by simply pressing the accel pedal to the floor and the boost will build within 0.5 second depending on your current engine speed. The Ignition will now be retarded therefore reducing engine torque, load on the clutches and the drivetrain in general.

The engine torque is around 70 to 130NM depending on RPM and boost pressure target. Inlet manifold boost pressure is around 0.2 to 0.5bar positive pressure depending on the calibration settings. Ignition Timing is around -20 deg

During this stage the Ignition Timing and AFR are controlled whilst a safe closed loop boost pressure is achieved – there is little real stress on the drivetrain but the EGT will increase steadily if the feature is held for continuous long periods.



Step 3 – Launching
The RRRL feature is deactivated by turning off the cruise control. This will cancel the RRRL closed loop Ignition control. Ignition Timing will be progressively advanced from around -20 deg to +15 deg and engine torque will progressively increase from 100NM up to 1000NM+ depending on the engine spec.

Inlet manifold boost pressure is around 0.8 to 1.5bar+ positive pressure depending on the calibration settings. Ignition Timing is around 5 to 15 deg depending on the above
You will instantly pull 0.7g or greater !!!




Some key points:

The engine torque value given to the TCM clutches is a calculated torque value (and not a measured torque value) so for this reason, as soon as the Ignition Timing is advanced, the TCM will increase clutch clamping pressure to receive the immanent surge in engine torque. You have now left the RRRL mode and the engine is producing full boost, power and torque for the given engine speed.

Several things can happen at this stage

If the target boost pressure was too high, the following could happen

· Rear tyres can slip momentarily whilst the torque is distributed and transferred to the front
· The clutches will slip if the torque is greater than they can physically hold (but this would be apparent on any full load run without rolling launch




If the target boost pressure and launch RPM are just right then

· The vehicle takes off like you have suddenly been hit from behind by a freight train (slight exaggeration but we are setting the scene)
· You surge ahead of your competitor as he waits for his turbo’s to build boost


If the target boost pressure is too low then following could happen

· The vehicle takes off like you have suddenly been hit from behind by a small vehicle
· You competitor takes off and leaves you behind because he has RaceROM Rolling Launch running a higher boost pressure than you.

The beautiful advantage with EcuTek Rolling Launch is the clutches are actually engaged the whole time, unlike a static launch where the clutches are NOT engaged and then suddenly engaged which as you can imagine places considerable stress on the clutches, gears and the rest of the drive train.

We hope you enjoyed this little feature and please post any go pros, pictures etc. to share your experiences with us.
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Old 19th March 2014, 04:25 PM   #2 (permalink)
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Thanks, good read.
How is the target boost pressure changed?
Also how long is too long whilst in RRLC mode for the EGT to become an issue?
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Old 19th March 2014, 04:31 PM   #3 (permalink)
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Quote:
If the target boost pressure and launch RPM are just right then

· The vehicle takes off like you have suddenly been hit from behind by a freight train (slight exaggeration but we are setting the scene)
· You surge ahead of your competitor as he waits for his turbo’s to build boost
Confirmed!
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Old 19th March 2014, 04:38 PM   #4 (permalink)
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Quote:
Originally Posted by cd09 View Post
Thanks, good read.
How is the target boost pressure changed?
Also how long is too long whilst in RRLC mode for the EGT to become an issue?
its set by the tuner in the switchable maps.

best not to sit on RRLC for too long 5-10 secs is about ok
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Old 19th March 2014, 04:46 PM   #5 (permalink)
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Interesting read.. Thanks
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Old 19th March 2014, 06:48 PM   #6 (permalink)
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Very interesting article. The only problem I had was with some of the acronyms. Being a fairly newcomer to the world of GTR, I was able to become AF (that would be au fait) with most. but was still left in the dark with AFR. Help anyone?
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Old 19th March 2014, 06:57 PM   #7 (permalink)
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Is this only on the latest ecutek software?
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Old 19th March 2014, 06:58 PM   #8 (permalink)
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Air fuel ratio
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Old 19th March 2014, 09:15 PM   #9 (permalink)
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Good write up Ben
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Old 19th March 2014, 11:15 PM   #10 (permalink)
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Ben
I'm Trying out the Rolling launch tomorrow weather permitting!!
Did a static Launch Today I thought the earth went backwards
This car is now super quick
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