I have a pair of Hallman MBCs with cabin controllers and am trying to fine tune my transition. I have a boost pattern of 0.84-0.62-0.84kg/cm2 and, according to my Datalogit logs, a 0.4 second transition (that is, the length of time between the final primary 0.84kg/cm2 setting to the first secondary 0.84kg/cm2 setting, with some error margin).

The transition certainly feels quick but I was wondering what typical transition times people are seeing in their logs.

 

You are the first that I know of to log this and ask about it.

With the DL, Settings 1 - Turbo Transition; you can lower the HIGH RPM side to see what happnes. One person tried this and said that it helped his turbo responce.

 

^I've lowered the high on mine about 80-100rpms, although I haven't logged to see how it affected it. I might try that in the next week or so, I haven't really thought to.

In reality it would be best to have the quickest(full boost) transition at the lowest possible rpms, since when both turbos are open you have a good bit more air flow, which should help the power band.

 

Thanks. I'll try playing with the high rpm setting.

Funny - there are many, many threads discussing transition but no real quantification of what a quick transition would be. A 0.4 second transition certainly feels quick (whereas 0.7 seconds feels like a pause) but I have no idea if, say, 0.2 seconds would be possible.

 

This is due to the fact that many of us pioneers of the PFC/DL went non-seq or single turbo before or about the time that the PFC/DL came out. Thus we never did the experimentation with it.