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      08-19-2011, 02:11 PM   #25
JimD
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Drives: 128i convertible
Join Date: Apr 2009
Location: Lexington, SC

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I checked the N51 3 stage versus a high output X5 N52 on RealOEM some time ago and they were the same. The N51 has lower compression, however, and also smaller injectors. The X5 has the 3 stage and different exhaust manifolds. I think it is rated 265hp.

Somewhere here there are dyno runs for a low mileage N52 with 2 stage intake and they look very very close to this higher mileage 3 stage conversion. The newer engine may have been higher. Hard to compare engines with large mileage differences but it didn't support a large gain for the 3 stage.

I think it is possible to gain horsepower with the 3 stage but only if the tune is good.

Jim
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128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09