Further dyno evidence of no under rating

[flinchy]

Originally Posted by swamp2

You've obviously not been keeping up with some of the newer developments. It seems likely that one contributing factor is a double SAE weather correction. The car largely corrects itself being able to output the same factory specified power across a wide range of conditions. Thus applying a correction factor to either trap times (as most magazines do) or to dyno results is an effective "double dipping" and will lead to the conclusion of under rating.

i have, read the whole thread, and every thread related

the ONLY 100% sure way to get accurate numbers would be on an engine brake

as that's not realistic, working with the information at hand, the S55 is underrated. Quite simple.

yes, which means it's putting out more power with the 'over correction'?.. most modern cars, even the E9x has similar tables, adjust timing based on inlet temps and fuelling, so i'm not sure what the difference is you're trying to describe?

doesn't matter how or why, because it's doing it, and that's all that matters.

plus, as said above, the temperature change, even if it was 100-110 degrees, wouldn't effect power more than a couple of hp assuming octane is enough and the cars weren't pulling timing (which looking at the numbers, they weren't).. air density doesn't change THAT much. clutching at straws.

Originally Posted by swamp2

Also, as has been discussed extensively, inertial dyno's just don't cut the mustard. One can get any result they want. This is well documented online and by the measured variance in the m3 dyno database.

So no, same, day, same, dyno, same operator, no, this is not sufficient nor quality information to conclude the absolute crank power of the S55.

and inertial dynos don't cut the mustard? in what way.. being too consistent from dyno to dyno? being able to accurately adjust based on gearing if known?

they more than cut the mustard for these purposes.

it's LOAD BEARING dynos that don't cut the mustard, i think you're confusing yourself - load bearing dynos have calibration/ settings that the operator can modify at will, to give a desired result.

same day same dyno same operator on a dynojet CANNOT be beaten for accuracy.

[Racer20]

I think part of the issue is that with modern engine controls, cooling systems, and aerodynamics, you can't just stick a fan in front of a car on a dyno and assume it's going to work the same as if it were driving down the road.

Airspeed, pressures, flow around the engine compartment, engine load, etc. etc. are all critical to the engines dyno results.

[swamp2]

Originally Posted by flinchy

i have, read the whole thread, and every thread related

the ONLY 100% sure way to get accurate numbers would be on an engine brake

as that's not realistic, working with the information at hand, the S55 is underrated. Quite simple.

yes, which means it's putting out more power with the 'over correction'?.. most modern cars, even the E9x has similar tables, adjust timing based on inlet temps and fuelling, so i'm not sure what the difference is you're trying to describe?

doesn't matter how or why, because it's doing it, and that's all that matters.

plus, as said above, the temperature change, even if it was 100-110 degrees, wouldn't effect power more than a couple of hp assuming octane is enough and the cars weren't pulling timing (which looking at the numbers, they weren't).. air density doesn't change THAT much. clutching at straws.

and inertial dynos don't cut the mustard? in what way.. being too consistent from dyno to dyno? being able to accurately adjust based on gearing if known?

they more than cut the mustard for these purposes.

it's LOAD BEARING dynos that don't cut the mustard, i think you're confusing yourself - load bearing dynos have calibration/ settings that the operator can modify at will, to give a desired result.

same day same dyno same operator on a dynojet CANNOT be beaten for accuracy.

And that is what BMW has done, 425 hp with EU regulations permitting a 5% variation.

Look, I used to be "on your side". I know the arguments. The castle has crumbled...

I'm probably just about done going round and round here. The evidence is there. Pretty well everything agree except inertial dyno data which is all over the map (as Boss330 has summarized).

Plug this into the SAE J1394 (1990) correction:

hp: 425 (crank)
temp: 110 deg f
pressure: 29.0 in Hg
humidity: 80%
resulted corrected hp: 486 (crank)

Any reliable evidence points toward minimal to no under rating. If you trust absolute crank numbers or even whp numbers from an intertial, that is your choice but it has been shown to be FACTUALLY unrealiable and inconsistent data. Believe what you like. It's also obvious that the more sophisticated "in the know" folks here also pretty well agree here.

"doesn't matter how or why, because it's doing it, and that's all that matters."

Precisely the sort of blasé unexamined attitude that leads to incorrect conclusions on all sorts of matters every day.

Originally Posted by flinchy

same day same dyno same operator on a dynojet CANNOT be beaten for accuracy.

Seems pretty clear that the Insoric "in-situ" dyno which can estimate/calculate losses does a much better job for both whp and crank hp.

PLEASE, PLEASE, say something new or insightful or just give it a rest.

[Boss330]

Originally Posted by swamp2

And that is what BMW has done, 425 hp with EU regulations permitting a 5% variation.

Look, I used to be "on your side". I know the arguments. The castle has crumbled...

I'm probably just about done going round and round here. The evidence is there. Pretty well everything agree except inertial dyno data which is all over the map (as Boss330 has summarized).

Plug this into the SAE J1394 (1990) correction:

hp: 425 (crank)
temp: 110 deg f
pressure: 29.0 in Hg
humidity: 80%
resulted corrected hp: 486 (crank)

Any reliable evidence points toward minimal to no under rating. If you trust absolute crank numbers or even whp numbers from an intertial, that is your choice but it has been shown to be FACTUALLY unrealiable and inconsistent data. Believe what you like. It's also obvious that the more sophisticated "in the know" folks here also pretty well agree here.

Precisely the sort of blas unexamined attitude that leads to incorrect conclusions on all sorts of matters every day.

Seems pretty clear that the Insoric "in-situ" dyno which can estimate/calculate losses does a much better job for both whp and crank hp.

PLEASE, PLEASE, say something new or insightful or just give it a rest.

And, the EAS dyno runs had the lowest IAT at 114 deg F I believe, with a 140 highest...

61hp correction on top of the engine already having taken care of correction (as that high 19 PSI boost reading also indicated)... No wonder we are seeing all sorts of inflated dyno results for the S63 and now the S55...

[swamp2]

Originally Posted by Boss330

And, the EAS dyno runs had the lowest IAT at 114 deg F I believe, with a 140 highest...

Are there multiple IAT data for F8X dyno runs? Please post. Would be nice to have a small reference set of data.