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Old 02-01-2013, 02:38 AM
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K-A K-A is offline
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Originally Posted by cordoor View Post
Rain man was right on. He was very good at math. So basically, by saying it is rain man math, you agree.

But based in your second sentence, I think you meant to say that it was Duh-bya math.

At any rate, K-A is probably right, but perhaps a bit high if you consider the 5er has an 8 speed gearbox. What matters is the total area under the HP curve from start to finish (I'm trying not to use math here). With the 8 speed gearbox, you stay at the top of the curve a bit more so you end up with more total under-the-curve area by the end of the run compared to say, the GT. So there is *some* benefit to the 8 speed gearbox (maybe it's 10-15 HP benefit or something; to know would require using math and I'm many years removed from that ).

But even if you assume a super efficient 15% drive train loss, then 277 RWHP puts it over the 300 @crank HP claimed by BMW (about 326 HP, to be more specific, which would probably be enough to get the vehicle to 100 trap with the 8 speed gearbox).

Originally Posted by Emilner View Post
It should be approx 330hp but 340 is not out of reach for a broken in motor. A fair parasitic loss number should be 16-18%.

Gearing is a good point to bring up, but still.

Using this example again, as I find this particular car a very accurate and solid basis for HP/Weight=Trap Speed.. the '03 Mustang GT with MANUAL (I'd assume the extra lack of drivetrain loss there could possibly equal out missing out on a few gears, who knows, but for the sake of argument....) has 260 HP on the nose (crank), and traps 100 (average). The 535i traps 100 MPH (average, I've seen some as high as 102 and some as in the high 90's, but with more broken in motors, I wouldn't be surprised if low-100's becomes more common), and weighs a good 800 lbs more. So, using the 100 lbs = 10 HP rule, we're looking at around 340 HP.

Considering gearing, and efficiency, I'd guess the N55 is putting 325-340 at the crank (a fair guesstimate).

Dyno's will range everywhere, but what's important is trap speed when trying to determine genuine power rate, IMO. So some N55's will dyno less, some more (and especially more when broken in some).

Remember, some guys with N55 3-Series' have apparently dyno'd in the 290's, stock.
'15 Porsche Macan S SportDesign | White/Black (Alcantara/Leather), PDK, 20" RS Spyder's w/ Colored Crests & Summer Tires, Air Suspension w/ PASM, High-Gloss Black Trim, Premium Package, Comfort Lighting, HD Radio, Tints.

'15 Mazda 3 i Sport.

Recents: '13 BMW 535i M Sport: Black/Black, Prem/Tech/Sport Auto/etc. M-B's: '11/10/06 E350 "Sport", '02 S500 w/ Every Option.

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