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Originally Posted by buildbright
Quote:
Originally Posted by Ilia@IND
While it's possible to make power improvements using a piggy back computer, you are ultimately changing input values to the DME by modifying sensor outputs.
Even when considering only one parameter- boost, for example- a piggy back solution is far from ideal. By modifying sensor output a piggy back will allow for the engine to create additional boost pressure. If a DME's target boost pressure is X psi, the piggy back will send a signal to the DME that equates to X - 5 psi. In an effort to maintain boost pressure, the DME will then close the wastegates to force the engine to produce X + 5 psi, giving the driver a power gain over stock.
The trouble with this scheme is that modern BMW DMEs are not simply Air/Fuel/Boost calculators like the performance car ECUs of 15 years ago, and take literally hundreds of sensor's inputs into account, across thousands of tables. Input boost pressure, air flow, and other factors that piggy back computers typically modify are only a small fraction of the bigger picture, and by modifying those factors without affecting any additional parameters you substantially handicap the DME's ability to control the engine safely.
A piggy back computer cannot modify a host of systems controlled by the BMW DME like the top speed limiter, air/water heat exchanger water pump control (important for maintaining the lowest possible IATs, and something few tuners have even looked at thus far), cold start, secondary O2 sensor sensitivity (important for using catless or high flow cat downpipes), the torque limit built into the DME from the factory, etc...
While it's possible to raise boost pressure over stock and maintain a safe air fuel ratio (in normal operating conditions) by using a piggy back computer, it is absolutely not a good way to control a modern BMW engine. The DME makes decisions based on data that is outright false, and as a tuner someone who uses a piggy back is introducing variables that can lead only to a decrease in long term reliability.
For this reason we will wait until a true control of the original BMW DMEs is possible, prior to offering any sort of modified software for the M5.
It would be easy for IND to sell software modification via piggy back right now, and it is of course tempting to begin to recoup the sizable investment we've made into the F10 M5 program right now, we must stand by our core values and therefore cannot deliver what we know is a poor compromise of an engine control solution to our clients. The S63tu is a very expensive engine, and I have no interest in controlling one via piggy back.
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I can respect that piggybacks are not for you but don't spew incorrect info. Any aftermarket item that changes engineered variable's can put increased stress on the engine. Thus causing decreasing reliability. This could be a simple exhaust or air intake.
If you don't like piggybacks don't sell them but don't say they are not safe because you personally don't like them. I personally am going to trust Hartge that has been tuning since 1971. Turner Motorsports which actually has a successful Motorsport record. BMS and others which have 10's of 1000's piggybacks installed and successfully working. What is you experience? |
I think you just highlighted Ilia's point. "[They] have been tuning since 1971".
When meeting with the BMW engineers, it was rather astounding to me just how many inputs the F10 DME receives from various components throughout the car. Definitely not as simple as it used to be.