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      07-25-2009, 11:55 AM   #14
Lemans_Blue_M
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Quote:
Originally Posted by MrHarris View Post
I thought the Euro E46 M3 had 343hp, compared to US 333hp?
When factoring in the differences of DIN (Euro metric HP calculation) vs. SAE (U.S. standard method of calculating HP) the difference is much smaller than 10 HP...

E46 M3 S54B32 engine output DIN: 343 HP

E46 M3 S54B32 engine output SAE: 338 HP

That's only a net difference of 5 HP

The only reason the U.S.-spec E46 M3's didn't get the exact same power as the Euro-Spec engines was our strict emission regulations here in the United States. The EPA/CARB emission standards that required BMW to moving the catalytic converters up into the actual exhaust headers to burn off more volatile exhaust gas hydrocarbons during cold starting conditions. (before the engine is fully warmed up)

That engineering revision caused a restriction of the exhaust gas pulses exiting the engine, and that reduced the exhaust gas savaging effect of the headers. This resulted in a slight loss in overall horsepower.

Euro-spec engines had their cats in the first mid-pipe section further downstream, so their engines did not suffer the same performance hit as ours.
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