Quote:
Originally Posted by BEAR-AvHistory
So what would it be at the wheels? What loss factor would you use for a 3/435? Be interesting to see what "Unlock 10 HP and 15 lb-ft of torque in under an hour" for $600 actually looks like at the wheels.
Reason I asked is because back in the bad old days when I was running a 335is with only a piggy back & one of the other 335is guys was running a lot of Dinan equipment we looked like this on page 8 of the BMW 335i section of Drag Times in positions 148 & 149.
148) 12.583*^ 114.529mph 8.062 90.430mph 2.070 BMW 335i 335IS 2011 BEAR-AvHistory
149) 12.590*+ 108.740mph 8.130 87.740mph 1.960 BMW 335i S Dinan Stage 3 Tune 2011 BuraQ
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Get asked the drivetrain loss question a lot so I will resort to a response that has been made in the past since its pretty comprehensive... if you wanted a concise non elaborate answer it depends on the transmission but the drivetrain loss typically caps out at 12-15% ---
"We do use a Dynapack chassis dyno and a DTS engine dyno for all of our testing. Like most OE's, we publish our crank numbers, not wheel horsepower numbers, simply to keep things as accurate as possible. Dinan tests multiple cars with multiple runs and averages them so no one chassis dyno test would be representative. When we compare our engine Dyno Data to our chassis dyno data we find that most if not all chassis dynos, including ours, overstates the lower RPM torque values. Our chassis dyno does not do a coast down for inertia and friction corrections. If we are using the chassis dyno once we have performed multiple Chassis dyno runs and averaged them we apply different correction factors to each RPM to correct for these inflated torque numbers. All this is done to ensure the most accurate reporting to our customers. We list both Stock and Dinan numbers using the same corrections to ensure the comparison is fair. If we are using the Engine Dyno the data is just averaged over multiple runs to get a fair average performance. With both the engine dyno and chassis dyno we ensure the room is as close to standard weather conditions as possible and all dyno runs are performed in the same weather window to ensure comparisons are fair. In most cases Dinan Dyno numbers will be lower than those you will get at low RPM because of the inaccuracy at low RPM previously mentioned. Also in most cases Dinan's numbers will be higher at hi RPM because of the work we do to ensure proper heat exchanging that we find almost no one else does.
A few years ago, we put together a really in-depth article on our dyno process and how even slight variables can affect the outcome of any test.
http://dinancars.com/dinan-university/ - (Dynamometer Testing and The Modern BMW Engine)
It's a long article, but it gives you a really detailed looks at the process with a conclusion that has a good breakdown of what we covered. The most accurate thing we can say is that we've observed over 36 years of tuning, with most models we've tested, that the drivetrain loss is between 6.5 and 15 percent. It’s not as simple as a percentage, as it varies on car, transmission, RPM, vehicle speed and a myriad of other variables."