Steve,
Heres the data I had from my completely stock Mustang dyno runs. NOTE: The dyno was being run in AWD mode, so both roller sets were connected.
As you can see my numbers were 249 HP and 252 Torque.
Going by these numbers for adding back in the 18% and 12%...
18% ... 82 * 1.2195 = 99.999
12% ... 88 * 1.1364 = 100.0032
18 + 12 = 30% ... 70 * 1.4286 = 100.002
Add back in the 18% drive train loss they told you to use...
249 * 1.2195 = ~303.66 HP
252 * 1.2195 = ~307.30 torque
IF the Mustang dynos typically show another 12% lower than say dynojets, then we add back in the 12%...
303.66 * 1.1364 = ~345.08 for HP
307.30 * 1.1364 = ~349.22 for torque
This looks VERY close to the numbers we had figured for the SRT6 (not advertised, but actually closer to the SLK 32 AMG)
Adding both percentages together and then doing just one step...
249 * 1.4286 = ~355.72 for HP
252 * 1.4286 = ~360.01 for torque
There IS a flaw in these calculations. My question is which is right...
Add in each percentage separately OR add the percentages together and then add back in the overall percentage???
By the way Adding 18% back in... is not the same as subtracting it! Because you are working with LESS than 100% for a starting number, you have to actually add in a higher percentage of the number to get a full 18% of the original 100%.
So, if you LOOSE 18% from say 330 from the drive line, you are loosing an actual 18%. 330 * 0.82 = 270.6 ... BUT, if you want to add back in this loss, you must add in MORE than 18% of 270.6!
270.6 * 1.2195 (21.95% added) = 329.9967
Make sense?