We’ve been working on a Motec PNP solution for the Porsche 996tt since we purchased our car. Starting off with a base jump harness Darin was able to wire the Motec into the jump harness without cutting a wire on the factory harness. If we even wanted to go back to a factory Motronic setup we can unplug the jumper harness and plug the factory ECU back in. I want to be the first to say this is not a replacement for a ECU reflash, and should not be considered as such. While the harness is plug and play, the setup and tuning of a standalone is anything but and should be left to only the most qualified of tuners. It’s not intended for a full daily driver or basic bolt-on turbo car, we’re looking to race the car heavily at both the drag strip and road course, and went with the Motec for on the spot control of the ECU, as well as the additional data that can be recorded and reviewed between runs during testing. We’ve had to do quite a bit to get the factory ECU to continue to control the vehicle while allowing the Motec to take control of the engines functions, but after a few days or troubleshooting we have made huge grounds and have the car running and driving quite smoothly, now it’s just a matter of turning the car up and making the extra power we hope for with the K24/18G setup.
As a result of converting the car to speed density we where able to remove some factory parts that are known to be restrictive. Here you can see the very restrictive plastic intake ducting that connects the airbox to the turbocharger inlet. Anyone who thinks that new shiny airbox or filter is getting them a ton of performance, remember it has to flow through this restriction before it ever meets the turbos.
Since we removed the MAF sensor and went to a speed density setup when installing the Motec we where able to use a standard air filter setup, our Fabricator John did a great job of routing the pipe through the fenderwell to the new filter location.
This image should show you how tight a fit the 2.5″ pipe is inside the wheel well. It took many test fits but John was able to make the pipe work while providing adequate clearance for our R888s to fit. We modified the intake ducting for the intercooler to provide fresh air to the filter as well, providing a true ram air effect that not only provides the filter with fresh air, but still maintains proper intercooling as well.
Since the Motec operates off a MAP sensor rather than a closed loop MAF sensor, we where able to remove the factory diverter valve setup and install a standard blow off valve onto the existing Y Pipe. We opted for a Tial BOV mounted at the front of the y-pipe for easy vacuum line routing and venting to atmosphere.
We’ve got a bit more fabricating and tuning to do, but hope to have the car on the dyno on Friday and if all goes as planned the car on the track that evening.