MoTeC GPRP-Pro

Hello Experts,

Is anyone experienced with the MoTeC GPRP-Pro package and the features it offers?

I have a fully functional street/strip car with a M150 GPR system and its working pretty good.

I recently wanted a change and wanted to test out the new Torque based TMS modelling MoTeC offers in their GPRP-Pro. Can anyone give us insights as to what benefits i could be looking at from switching to this firmware?

I have had a look at MoTeC published setup guide, but I want input from the guys who have used this package.

Thanks

It's pretty simple -- torque based modeling works to produce only the power that can be expected to be used. This means the traction control doesn't have to do 60% cuts to tame a 2000 hp beast, when it's only producing the 800 hp that can actually be used in the current conditions (gear, aero loads, etc).

I am in process of doing my first GPRP-Pro tuning, and while it hasn't been finished / tested, it certainly seems that what the setup manual describes is what I will be able to deliver. It does require significant dyno time and a methodical approach to tuning.

Track tuning will consist of determining what amount of traction is available.

Crystal clear.

So the GPRP-PRO will bring on this passive traction control sort of thing.

I'm sort of interested in the Throttle mass flow fueling and how it will affect driveability.

Would you say that this sort of package would make a difference in a drag/street racing application?

Or perhaps in a desert/rally application?

The torque modelling functionality of GPRP-Pro has been around for awhile, as it is based on the R35/Huracan Torque based model. The GPRP-Pro Package has also been used in off road racing.

AD.Wolf,

The only question I would really have for you is what transmission do you have in the car?

I ask ask as there isn't super strong support in the firmware for a drag racing style automatic transmission in GPRP-Pro.

In regards to the throttle mass flow calculations influence on fuelling - that is a bit of a tricky one to answer. In GPRP pro, the is a modelled inlet manifold pressure, which is derived from the throttle area table, throttle position, throttle mass flow area factor and the resulting throttle mass flow calculation. The only time this can influence fuelling behaviour is if the kalman gain for the inlet manifold pressure is reduced from 1000, otherwise the inlet manifold pressure sensor will be used without conditioning (the same way in non torque GP firmwares you can have the inlet manifold pressure mode set to sensor)

Reducing the kalman gain will consider both the inlet manifold pressure modelled and the inlet manifold pressure sensor value, with the kalman gain set deciding the ultimate contribution of each of these for the inlet manifold pressure value used for fuel and other calculations.

This could almost be compared to the inlet manifold estimate blend and decay - although where these are only present in transient events in non torque GP firmware, the blend in pro is always present.

This is why the Kalman gain has a table axis to allow for a bias of this in engine speed regions - for instance where camshafts cause a lot of overlap and reduce your inlet manifold pressure signal resolution you may wish to lean more heavily on the modelled value.

With the firmware carefully configured, it is possible to drive the car afterwards on the modelled value only setting the inlet manifold pressure kalman gain to 0 - i have done this on my own car as a proof of concept.

As David has outlined - it is a more complex firmware to calibrate and far more time consuming (this gets better when you have calibrated several cars with the firmware and start ti develop a workflow that suits your tuning methodology). It is also far less forgiving with less accurate sensors and sensor calibrations - a key one here being your inlet manifold pressure and boost pressure sensors in a turbocharged application. Any differential between them will affect the inlet manifold pressure modelled and torque calculations - as you begin calculating a pressure differential across the throttle that isn't there.

I have seen 5-6 kpa differences when 4-5 bar sensors are used and even instances where the sensor placement can cause deviation in how the sensors read. A car i recently worked on had the boost pressure sensor in a boss in a straight charge pipe before the throttle and the manifold pressure sensor in the back of the plenum. At 1.3bar of boost, the boost pressure would read almost 8 kpa lower than the manifold pressure (response was not turned on, so we had 100% throttle servo) which affects the modelled manifold pressure, throttle mass flow and several other items. As the engine is in the region of 1500hp at this boost level, there is also a near 100nm error in the modelled torque calculation.

I greatly appreciate your inputs Stephen and Nathan.

I plan to install this package on a manual (to be Sequential in the future) supercharged vehicle that will be used for off-road purposes with occasional road driving.

For the pressure sensors post and pre-throttle, I will try to place them as close as possible to the throttle (will tap the Throttle body if needed).

But how would this sort of reliance on the pressure drop across the throttle body be handled in the case of WOT? I assume it would default to the pressure sensor or something of that sort?

And in the application of the torque modelling, would i be able to control the torque from a SC vehicle?

AD.wolf,

So you are referring to a PD blower setup like a whipple or equivalent as opposed to a a procharger which is pre throttle?

The next public update of GPRP pro will have an update for handling the torque model in this scenario - the current version doesn't handle this as well, due to the the pressure differential behaviour not only occurring across the throttle.

It uses pre and post blower inlet manifold pressure sensors as well as measuring any differential across the throttle with the pre supercharger inlet manifold pressure sensor and the ambient/airbox pressure.

The pre/post inlet manifold pressure sensors also allow the torque to track when the bypass valve is active.

You're exactly right Nathan, so i need 3 pressure sensors for this to work (pre-throttle, post-throttle, and post PD rotors and aftercooler)

I'd better get accustomed to this package till that update rolls out then.

Is it planned for any time this year?