Quote:
Originally Posted by BMW M4 PWR
Oh Jesus Christ here we go again 
Put simply, its the correction everyone uses on the dynojets, which CANT be altered by dynojets operator... so for example, an SAE figure on an M3 on one dynojet can be accurately correlated with another M3 at a different dyno / different day but SAME SAE correction factor. The delta between them is as close to accurate as you can get... as long as you use the machines same scalar (SAE vs SAE or STD vs STD)
There's more to why correction factors are still applicable to modern sophisticated self corrected turbo motors (albeit not as much as N/A motors) but frankly, that's a novel I don't care to the write a dissertation on, along with the BS back and forth for a WEEK by every "Sunday engineer" on here... and particularly on the Saturday before Christmas... (Damn soccer moms are violent in the isles of the malls, watch out!  )
Just remember, the ONLY two things that matter in posted dyno results. #1) The correction/scalar being used, and #2) that it's a FIX'ed correction/scalar that can't be altered by the type of dyno. (Generally dynojets) ...then and only then do you have as close to "apples to apples" as you can have when comparing different cars... |
Are you saying that Dynojets can't show uncorrected WHP? If so I did not know that...
Regardless, applying SAE/STD correction to these engines actually mean that you can't compare from one dyno to another, unless the dyno's are next door to each other and have the exact same ambient conditions... Because there isn't such a thing as a "fixed" correction... The whole point of correction is that it varies according to varying altitude and ambient conditions.
If you have one dyno at sea level and one at 2300 feet the SAE/STD correction will be very different between the two dynos. Same with ambient temps and intake temps, if they are different then the correction will also be different.
Those correction factors are there for one thing, to equalize measured power on engines that is affected by these varying conditions. For a engine that self corrects for this, correction adds a false value.
Let's say that you take a F8x and dyno it on three different dynos on different locations. At different altitude and ambient conditions. The uncorrected whp will be the
same at all three dynos, since the DME adjusts boost etc to compensate for these different conditions. But if you add SAE/STD correction, you end up with three
different HP numbers (because correction factors are different, see explanation at the end of the post).
Now, let's say you dyno a E9x M3 on three different dynos on different locations. At different altitude and ambient conditions. The uncorrected whp will be
different at all three dynos, because the engine power is affected by these different conditions. But if you add SAE/STD correction, you end up with three
similar HP numbers (because correction factors are different in order to cancel out differing conditions).
So, on a traditional engine you NEED to add correction to be able to compare. On a modern engine you must NOT add correction to be able to compare.
And, this is not "just a Sunday Engineer" statement. But something that is stated in the SAE and EU standards and explained in more detail here (by MAHA engineers and respected German Magazine Sport Auto):
http://f80.bimmerpost.com/forums/sho....php?t=1206686
http://eur-lex.europa.eu/LexUriServ/...12:0046:EN:PDF
Quote:
2.3 Power correction factors
By way of derogation from paragraph 5.1 of Annex V to UNECE Regulation No 85, when a turbo-charged engine is fitted with a system which allows compensating the ambient conditions temperature and altitude, at the request of the manufacturer, the correction factors α a or α d shall be set to the value of 1.
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Here, correction factors as per ECE 85 is defined:
http://www.unece.org/fileadmin/DAM/t...es/R085r1e.pdf