Quote:
Originally Posted by R32 Combat
Ever since the CAS was used, Nissan found that the ignition timing would drift as 4500-5000rpm. This is caused by engine harmonics in it's STD form and there is nothing physical that can be done about it. Nissan got around this be basically not using the CAS through this rev range and calculating the ignition timing using engine speed. All cars with CAS suffer from this. Which is why Toyota don't use this system. As soon as anything is changed in the valve train, the rpm of ignition scatter changes, which is why DET is so pronounced in the RB engines.
|
I have never heard of this in the factory ECU. I will enquire into it myself. I know that at higher RPM's we see some RPM drift. The thing is that the RPM is picked up off the CAS.
The CAS is belt driven, and I think the belt moves around a little. One a 600 hp car under load, I would see the RPMS move around 200-600 rpms up and down. Thats on a new build, with a new motor. If you are on the Datalogit group - for Power FC. In the files section, there are some logs of Nicks car 11 second runs. You can see in secessive frames the RPM's bouncing.
I remember reading that Mario - Exvitermini had issues with the Motec and the Nissan CAS. I think they were seeing something similar. Big rpm movements frame to frame.
I have a Nissan CAS that was altered to run a pre- Nissan CAS AEM. They made a new wheel for it. Seemed to work out ok on that car. It did over 900 whp.