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911st 911st is offline
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Join Date: Jan 2004
Location: Sacramento
Posts: 7,269
turbo lag, short v equal length headers.

Stole the following data point from another thread that pretty well displays to potential effect of smaller volume exhaust header compared to a more free flowing equal length system.

I suspect volume of the header system, including the wast gate pipe, has a direct correlation to turbo response.

The larger the volume the more area that has to be pressurized.

There will always be examples where design or other factors overcomes.

This example is a stock restrictive compared to a race system so the HP levels in the upper ranges might be discounted.

It may be a better designed shorty system could better approach the equal length depending on the design. However, the equal length has the advantage of better timing the exhaust events which reduce back pressure over a shorty system.

The same principle seems like it would apply on the intake side as the amount of volume that has to be pressurized.

Originally Posted by beepbeep View Post

... Here is dyno papers from identical engine configuration. One pull is made with trick equal length headers and other with complettly OEM cast-iron non-equal length exhaust manifold with narrow ports. As you can see, equal length headers give more power (some of extra power might be explained with boost runaway due to less backpressure) but they also spool the turbo 300-400 RPM later.

Old 01-08-2010, 08:27 AM
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