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Old 06-27-2010, 09:17 AM   #1257
Scooby Newbie
Member#: 116814
Join Date: Jun 2006
Location: Colorado Springs
2003 wrx wagon

Default Caution: IWG porting trade-off

Porting the turbine inlet and compressor outlet should be of some benefit, but I would caution against porting the wastegate. Doing so would likely increase the boost taper seen by rcodea in the upper range (currently from 21 psi peak to 16 @ 6600 rpm with MBC). To maintain higher boost in the upper range, it'll be necessary to increase the EBCS WG duty cycle to close down the WG as rpm increases above 5000 rpm. Porting the WG would have the opposite effect and possibly make it more difficult to maintain higher boost in the upper range.

The exhaust housing outlet diameter was enlarged by PT to accommodate the larger H wheel. This resulted in an outlet area increase of ~ 15%, and should be enough to accomodate the higher flow capability of the 19T compressor wheel. Porting the WG may offer some benefit in the mid range where there is an excess of exhaust manifold pressure (relative to that required to achieve target boost), but for reasons stated above, will be a trade-off that may increase midrange performance at the expense of top-end.
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