What gives the 6er's I6 "15" more HP than the 5ers I6 (N55)?

I put 15 in "_" because we all know the N55 is underrated on paper, therefore it'd be interesting to know how each compare on a dyno.

Sorry, didn't run a search in case it's been answered yet, but I'm curious as to what gives the 640i the extra little "boost" in HP from the 535i/etc.

Thanks.

All I have seen mentioned was that it was reprogrammed for more power (probably a little extra turbo boost) while maintaining the same fuel efficiency. I would assume the N55HP has a simliar amount of underrating as the N55.

Ah, cool thanks. Makes sense.

So is the 6's N55 referred to as the N55HP?

Based on my calculations of 20% Automatic drivetrain loss and the dyno I've seen of a 535i putting down 277 RWHP/283 TQ, then assuming with a few more break in miles a roundup to 280 RWHP would be easily feasible, we're looking at what seems to be around 335 crank HP. I wonder how the 6ers N55 would dyno.

Interesting thing is they've dyno'd 335i N55's to have over 290 RWHP in stock form, but amongst the only 1-2 535i dyno's I've seen it hasn't seemed to break that figure yet.

Just did some research. Figured out the "N55HP" thing.

Crazy thing is it makes 330 Torque, which means that maybe the differences are more significant than the almost negligible 15 HP would seem to imply?

Originally Posted by K-A

Ah, cool thanks. Makes sense.

So is the 6's N55 referred to as the N55HP?

Based on my calculations of 20% Automatic drivetrain loss and the dyno I've seen of a 535i putting down 277 RWHP/283 TQ, then assuming with a few more break in miles a roundup to 280 RWHP would be easily feasible, we're looking at what seems to be around 335 crank HP. I wonder how the 6ers N55 would dyno.

Interesting thing is they've dyno'd 335i N55's to have over 290 RWHP in stock form, but amongst the only 1-2 535i dyno's I've seen it hasn't seemed to break that figure yet.

The 535i does make around 330hp on crank.
It makes sense seeing how the 4200lb+ car can accelerate 0-60 in 5.6 sec.
15hp is not big of a difference for sure. The 5 can easily get a $500 burger tune to increase that to 350hp.

Originally Posted by smashhell

The 535i does make around 330hp on crank.
It makes sense seeing how the 4200lb+ car can accelerate 0-60 in 5.6 sec.
15hp is not big of a difference for sure. The 5 can easily get a $500 burger tune to increase that to 350hp.

Yeah, I've been doing research and it seems like the 250-300 lb heavier 6 Gran Coupe with the N55HP motor is a little slower (consistently via various different publications) than the N55 535i in 0-60 and 1/4 mile times (namely on trap speed), for what it's worth.

Yeah, been doing some research on the N55 cars dynoing and it seems at least 330 HP crank is what it truly makes. I'd assume that a broken in motor should be pushing 340. No way does a car that feels like this and traps over 100 in some tests have "only" 300 HP at this weight level.

It almost as if BMW likes to report their Wheel HP as their Crank HP.
When compare to other similar cars with similar HP, BMW always out perform. (say G37 vs 335i, 330hp vs 300hp, 3600lb vs 3600lb, RWD vs RWD; but 0-60 comes out to 5.6 vs 4.9, does not make sense unless the 335i is seriously underrated)

The 640i is running slightly higher boost(11psi at peak) than the 535. All through programming thats all. I am running at 16psi peak.