Options sport 8HP expliquées : blip, bump et trans-brake
Blip, bump and trans brake are three separate functions in the TurboLamik sport options set, and only two of them are used together. Trans brake holds the car still under full power for a launch, bump is a staged forward creep used with the trans brake at the start line, and blip is a downshift function that belongs on a road or drift car rather than at the drag strip.
| Function | What it does | Where it belongs | Precondition documented |
|---|---|---|---|
| Trans brake | Activates all clutches in the gearbox, as if to put forward and reverse at the same time, so the engine makes full power without transmitting it through the driveline and the car stays still | Drag racing launches | Manual program, vehicle stopped |
| Bump | Reduces clutch pressure during the trans brake so the car rolls forward gently, then locks it back in place | Drag racing starts, used while in trans brake | Vehicle in trans brake, gear up held |
| Blip | A throttle request from the TCU on downshift so engine speed matches the next gear | Road, circuit and drift use | ECU able to act on the request |
Blip: the TCU asks, the ECU acts
A blip is a brief throttle opening during a downshift, raising engine speed so the next gear engages with the engine already spinning close to the right speed for it. The important architectural point is that the TCU does not open the throttle. That is the engine controller's job. TurboLamik documents blip as a request the TCU raises on its CAN output, and it is visible in the documented streams:
- TCU stream v2 TX, byte 5 bit 1 is a "Blip request" flag, transmitted at 100 Hz.
- TCU stream v1 TX, FLAGS1 bit 7 is "Blip out", active when set.
- In the Holley stream, "TCU Blips" is sent as CAN ID 1824, input 6, at 50 Hz, as a flag.
So the success of a blip depends on your engine management system acting on that flag, which is why the manual's ECU pages all cover torque reduction. The same stream carries "Target Engine Torque (TQ Reduction)" in Nm and a torque reduction percentage, so the ECU has both the request and the torque context to execute the shift cleanly. If your gearbox downshifts without any blip, the problem is almost always on the ECU side: confirm the CAN stream is reaching the ECU and that torque and blip handling is configured before you look at the gearbox. Blip parameters are set in the tuning software, and their names are not reproduced here because the manual's Blip page presents the function rather than a written parameter table in the material this article was built from.
Bump: controlled creep at the start line
Bump exists for one problem. In drag racing you want to stand in front of the starting line, build boost, then creep forward just enough to turn on the start lights without loading the driveline. The manual describes the trigger as: while in trans brake and holding the gear up paddle or button, also press the gear down paddle or button.
Mechanically, bump reduces clutch pressure during the trans brake so the car rolls forward. The TCU counts the steps with the gearbox output sensor, and once it has counted the set number of steps it locks the vehicle back in place.
| Parameter | Documented effect |
|---|---|
| Enable bump | Turns the bump function on |
| Pump base clutch pressure | The initial pressure applied when the bump function is activated |
| Enable ramp, pressure reduction | A ramp that lowers clutch pressure when bump is activated; enabled by default after an update |
| Pump Torque pressure correction | Raises pressure on the clutches in proportion to engine torque. If set correctly, the manual states the thrust force of the car is constant regardless of engine torque |
| Pump Max distance | The distance the car is to travel, counted in pulses from the gearbox output rpm sensor. An 8HP gearbox produces 40 impulses per one turn of the output, so a value of 10 equals one quarter of a turn |
| Pump distance Clutch pres. up | Pressure build-up while the car is moving. Clutch pressure increases by the value entered each time an impulse from the rpm sensor is detected, which prevents the car from accelerating |
The distance parameter is the one to think about first. Forty impulses per output revolution means 40 counts per full turn of the output shaft, so a value of 10 is a quarter of that turn: bump distance is set in fractions of an output shaft revolution, not metres. The torque pressure correction is what makes bump consistent, because scaling pressure with engine torque gives the same forward thrust on low boost as on full boost. If you have an F series selector, the manual notes the P button can be used in place of the gear up paddle or button.
Trans brake: the full sequence
Trans brake activates all clutches in the gearbox, as if putting forward and reverse at the same time, which lets the engine create full power without transmitting that power through the driveline so the car stays in one place. The documented procedure:
- Enter the manual program.
- Stop the vehicle.
- While holding the brake, pull the gear up paddle or button.
- You can now release the brake, press the accelerator and enter boost.
- When you release the gear up paddle or button, the vehicle will start.
Note the order. The brake is held while you pull gear up, and only then released. If you release the brake before pulling the paddle the sequence does not match the manual and the car will not hold as described. Trans brake also appears on the CAN output: byte 5 bit 2 of the TCU stream v2 TX is a "T-Brake activation" flag, with a related "T-Brake or Launch control activation" flag at bit 4 and a "Burnout activation" flag at bit 5. The TCU stream v1 TX carries a T-Brake bit in FLAGS1, and the Holley stream includes a TCU T-Brake flag. Seeing that flag correctly is the first thing to check if a trans brake does not hold.
The warning that applies to both
The manual carries the same attention note on both the trans brake and bump pages: use this option consciously, you can damage the gearbox or the drive shafts. That is not boilerplate. Both functions manipulate clutch pressures in ways the gearbox was never asked to do in a factory car, and they do it at full engine torque. If you are new to either, start with the lowest workable values and change one parameter at a time.
Which one do you actually want
For a drift or track car, trans brake and bump are irrelevant, and your tuning time belongs on blip and torque reduction. For a drag car, blip matters less and trans brake plus bump is the whole launch strategy.
Frequently asked questions
Does the TCU control the throttle for a blip? No. It raises a blip request flag on CAN, and the engine management system performs the throttle action and the torque reduction.
Can I use bump without a trans brake? No. Bump is documented as a function performed while in trans brake, triggered by the gear down paddle while the gear up paddle is held.
How far does bump move the car? It is set as a distance in pulses from the gearbox output rpm sensor. With 40 impulses per output revolution, a value of 10 equals a quarter turn.
Can I release the brake before pulling gear up? The documented order is brake held, then gear up, then release the brake, then accelerator.
Is trans brake hard on the driveline? The manual states plainly that misuse of trans brake or bump can damage the gearbox or drive shafts, so treat both as functions that need careful setup.
Next step
Tell us what you are building and how you intend to launch or downshift it, and we will talk through which of these functions is worth configuring and what the gearbox needs to support it. If you are chasing a blip or torque reduction problem, tell us which ECU you are running so we can point you at the right integration path.
All function behaviour, parameter descriptions, trigger sequences and CAN flags in this article are taken from the TurboLamik official manual at manual.turbolamik.eu.