Thread: Muffler Choices
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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269

As you know, boost occurs when the differential pressures about the turbine wheel reachs a minimum threshold level. Increase pressure in the area after the trubine and we need to wait for more pressure to be made by the motor up stream to before we see boost.

Thus, the later boost threshold in this case would imply an increase in back pressure in the low rpm area of operation.

But why are we not seeing any impact on peak HP over a 3" Zork?

For some reason it seems the hot side of this turbo dose not need to flow anymore exhaust volume to support the 400hp.

This may indicate the turbo's turbine has become the restriction (choke point) and not your improved 2.5" system.

Thus, we probably can put as large of an exhaust on this thing as we want and it may not make any more HP as the turbine probably just can not flow any more.

Interesting thoughts.

Thus, I do not know the modified Monty is any indication that a 2.5" can support big HP or even 400hp in all cases. On a turbo with a larger flow rate hot side this may not be the case.

It is also probably not conclusive evidence that a tight 180 turn would not have an effect on back pressure at some point or even in this case, as evendenced by the later boost response.

It may be that anything larger than a well designed 2.5" straight through muffler on a smallish hot side turbo or K27-7200 hot side may not be needed to make HP.

Thus, it is not peak HP that may be determining exhaust size after the turbo but the flow rate of the turbo's hot side.

Very interesting!
Old 05-18-2010, 08:26 AM
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