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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
I am not sure what I experienced is termed over-boost or not.

With the K27-7200, the Tial just ran at a higher than spec level. I have long suspected that is how the B&B's make part of there power gain --from tricking the WG with a less than ideal angle. Most of us were going to the Tial to ensure better boost management at the time.

I am staring to believe that is the best place to put a WG on a shorty header system as that is where the volume of the secondary tubes have to restrict down almost by half to enter the turbo. But that is another discussion.

I did however latter experience boost creep that did create an over-boost condition when I went to one of the early HF prototypes. In that case even with my .7 bar Tial, boost would creep up to 1.1 bar. Probably as noted because the WG circuit was to small.

Jim makes a good point about using an EBC ! It can keep the WG from leaking before target boost level is reached. Not sure but I think it needs to be the type that has a set up procedure or logic that learns the boost curve. This locks boost down until the target is reached and then opens is just as much is needed to maintain said boost.

That was one of the selling points of the EBC's years ago. That they added power right where you needed it. The difference between relying on the WG spring and using the EBC could be seen on a dyno. The kink in the TQ curve as the boost target was reached could better be seen.

I found the EBC effective enough that I was actually able to tame my over-boost issue from the early HF (big compressor/small turbine) and hold boost at 1 bar.

Did not make sense to me but that is what it seemed to do.
Old 06-17-2010, 05:40 PM
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