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R32 Combat · 27th September 2006, 11:10 AM

Mapping, now there's a topic.

I've found out some interesting information about Nissans and the CAS.

This is what I've been told by 'a man who knows'

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.

Motec, Autronic etc all suffer from ignition drift. This is why the Japanese are so keen to run with a piggyback system which utilises the Nissan 'fix' for this problem.

AEM and GEM's are both working on a fix for this. The problem is, the American customer base for the RB26 AEM is very small for it's a low priority for them. As soon as an acceptable solution has been found, it will be implamented on my car and I get a free mapping session.(Bonus)

This is the only problem with the AEM, it's not just an AEM problem, but a nissan bodge from the very beginning.

However, until then, I'll be running a safe 1bar boost with safe ignition timing.

I've hatched a plan to run the CAS straight off the bottom cam pully, which will eliminate all these issues and make for a cracking setup.

Back to my mapping. Although I've not dyno'd it yet, the car runs perfectly, drives very smoothly and is very quick. The turbo lag is greatly reduced and I no longer use the ALS for launches, it lights up all 4 wheels with great ease. It's time to activate the launch control me thinks.

I'll be running @ pod for wheeze and see what I can break.(probably the gearbox and my wallet(again))

These are no issues with the conversion, everything works and I think its a great conversion.

Maybe in hind sight I would have opted for uprated conrod's, but there does it all end????

27th September 2006, 11:10 AM	#173 (permalink)
R32 Combat New Users Join Date: Jan 2004 Location: Berkshire Posts: 4,341	Mapping, now there's a topic. I've found out some interesting information about Nissans and the CAS. This is what I've been told by 'a man who knows' 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. Motec, Autronic etc all suffer from ignition drift. This is why the Japanese are so keen to run with a piggyback system which utilises the Nissan 'fix' for this problem. AEM and GEM's are both working on a fix for this. The problem is, the American customer base for the RB26 AEM is very small for it's a low priority for them. As soon as an acceptable solution has been found, it will be implamented on my car and I get a free mapping session.(Bonus) This is the only problem with the AEM, it's not just an AEM problem, but a nissan bodge from the very beginning. However, until then, I'll be running a safe 1bar boost with safe ignition timing. I've hatched a plan to run the CAS straight off the bottom cam pully, which will eliminate all these issues and make for a cracking setup. Back to my mapping. Although I've not dyno'd it yet, the car runs perfectly, drives very smoothly and is very quick. The turbo lag is greatly reduced and I no longer use the ALS for launches, it lights up all 4 wheels with great ease. It's time to activate the launch control me thinks. I'll be running @ pod for wheeze and see what I can break.(probably the gearbox and my wallet(again)) These are no issues with the conversion, everything works and I think its a great conversion. Maybe in hind sight I would have opted for uprated conrod's, but there does it all end????