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- GTP_Orido
Who are you quoting? Race gas vs 91 octane consistently adds 10 hp? In what cars? You can use a bloody million octane fuel in a car tuned to run 91 and it won't add anything. Octane rating is just a measurement of a fuel's knock resistance. Unless you're changing the tune on a car, using higher octane fuel than the car has been tuned for makes no difference other than costing more.
This reminds me of a friend of mine who was convinced he could "feel the difference" in his crappy old Commodore when he ran 98RON premium in it lol.
For the quote, you can read here : http://f80.bimmerpost.com/forums/showpost.php?p=16459929&postcount=11
Also read here :
http://f80.bimmerpost.com/forums/showpost.php?p=16517925&postcount=190
"I believe that there is a lot of misinterpretation of the term "drivetrain" losses in the discussion here (and in general). By definition, drivetrain losses are the losses incurred by friction in the transmission, bearings, differential and CV joints. However tire drag and slip losses, engine ancillary losses and inertial effects should not be included in drivetrain losses.
10% pure drivetrain loss is not an unreasonable number IMO. Looking at the Rototest results, I found drivetrain losses to be in the 6-10% range. Add to this tire drag and inertial effects and the difference between crank power and WHP can easily reach 15-18%. But that 15-18% is more than just "drivetrain" losses."
Interesting discussion there Tire pressure alone can influence dyno reading, intentionally raising or lowering tire pressure can give interesting results. I think a better term is parasitic loss. Japanese tuner tend to use lower % at 10-13 ( depending on MT or AT ) as often they use Dynapack, which is different as it runs on wheel hub.
I wonder what your friend would say if he drive Commodore or Falcon running on gas like the taxis Can he feel the difference ? Back in early 2000, most young import enthusiasts in my circles know that ECU tuning is very crucial part to make sure the cars perform well and reliable no matter what fuel used to run, some just ran piggyback, some use standalone like EMS, Wolf EMS, and expensive one like Motec or plug n' play like PowerFC. Cars also can have more than one mapping on stock ECU for different conditions, usually one of them is for safe mode, but I also heard special mode for emission test / factory mode ?
There's also aftermarket solutions to allow storing of multiple maps, and change of mapping at user discretion ( been in a car that can change maps using cruise control switch )
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