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If you look at the second sheet it shows "SAE" up top for the correction factor where the first is "uncorrected". SAE is calibrated for specific air temperature and barometric pressure baseline numbers to produce the dyno correction factor used in the chart. If you google "sae correction factor" you can find some pages with specific details about it.
So which numbers are the more accurate ones to go by?
The SAE correction is pretty much an industry standard. Otherwise, testing conditions will skew the numbers.
But dynos measure power at the wheels while car makers quote power at the crank. Applying even conservative wheel HP to crank HP correction puts this at close to 700 hp! https://www.mk5cortinaestate.co.uk/calculator4.php
In order to get crank’s numbers take a number on the paper and multiply to 1.15.
1.2 is probably more accurate because of the all-wheel drive. You're accounting for total drivetrain losses and we have an extra two differentials to account for.
Which raises another question. Is this a four-wheel dyno? I do know that these wheel numbers are similar to ones seen with four-wheel dynos but I don't know anything about how this engine was tested. In any case, all the tuners admit the stock baseline is around 690 peak hp. I have no idea why MB derates this engine so much. Leave room for higher power claims in more expensive cars?
1.2 is probably more accurate because of the all-wheel drive. You're accounting for total drivetrain losses and we have an extra two differentials to account for.
Which raises another question. Is this a four-wheel dyno? I do know that these wheel numbers are similar to ones seen with four-wheel dynos but I don't know anything about how this engine was tested. In any case, all the tuners admit the stock baseline is around 690 peak hp. I have no idea why MB derates this engine so much. Leave room for higher power claims in more expensive cars?
"Better to appear intentionally under-promising than deceptively exaggerating". Their claim power figures and acceleration times are usually given for worst possible conditions so that you're almost always guaranteed to perform better than quoted figures. It keeps someone from being able to dyno their car in the hottest, thinnest air possible and complain about power inferior to Mercedes' claims.
03-30-2019, 11:57 PM
