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I'm at a tuning stand still, all in all, it's been very frustrating, not an SDS problem though. Mostly it's a lack of funds and resources. I've always had something going on that I couldn't pin down when trying to run high boost in the upper rpm ranges and another thing that would happen right at 4K, now I think that they are related.
I've had very little luck tuning with a standard A/F meter, so it is really impossible for me tell what is really going on. I really like the SDS system and the programmer, but I tell you, for street tuning, you really need some sort of data logging and a system with good boost control software would be nice too. Road Dyno has been helpful, but I can seldom get the three runs,(as programmed, rich, lean), I need to analyse the system and I can only get it to work with a totally stock ignition.
With all this talk of duty cycle, I finally got a friend to help me investigate it further. Basically I found that the engine can start acting stupid at duty cycles as low as 80% and this can happen at 4200 rpm if over 15psi and it will act all kinds of stupid above 6K, after boost drops, duty cycle comes down and it will clean up.
The more I think about it, the Autronic System may be a good choice, even for a street car, if the ignition is as tunable as the SDS system. Like I said before the rpm settings are almost the same once you reach the torque peak, and except for off idle the load slope is linear, gaining a little at high boost to fight detonation. I can drop the load settings accross the board and not compensate for detonation with my water injection running, this drops duty cycle and is the only way that I can run boost at 15psi.
Below is a 15psi run with the hybrid turbo, at the wheels, (stage 3 Turbonetics, .82 AR turbine housing, super V cold wheel). It works well, if you keep it at or above 4K, but I can't run high boost or redline because the injectors are maxed out. I've got a turbo off a Thunderbird Turbocoupe, (.63 AR turbine housing, 60 cold wheel), that I'm going to try before looking at getting at getting a smaller AR housing for the hybrid.
posted by 204.214...
, Sat, 22 Sep 2001 18:42:36
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