SuperFlow AutoDyn, Руководство оператора, Страница: 208 / 208

Fundamental Concepts to Obtaining Superior Repeatability
Volume 3, 9/10/04
Appendix B - Page 215
don't repeat well, so by averaging the tests, you'll get a much more realistic picture of
what the engine is doing. You can also average columns of data in WinDyn.
• Always optimize the engine after any changes. Try to return to the same A/F ratio
setting before determining if the change made an improvement or not.
• Also, optimize the A/F ratio for atmospheric conditions. Hendrick Engines uses O2
sensors in each cylinder and one in each collector. They believe O2 sensors are
crucial for repeatability.
• Try to minimize the correction factor, if possible. Don't dyno on "bad air" days.
• Systematically return to the baseline configuration during the course of your testing.
This helps insure the improvements you saw were indeed from the changes you
made.
• As atmospheric conditions change, re-establish the correct A/F ratio.
B.4 The Engine
• The engine must be properly broken in using your established break-in procedure.
• The engine's state of tune is critical for good repeatability. A badly running engine
simply will not repeat.
B.5 Tuning tips
• Remember, G-forces can't be duplicated on the dyno, so jetting on the dyno will be
different than jetting required on the track.
• Jet for maximum power, and let BSFC fall were it may.
• Use step testing to jet and to work on BSFC. Step testing is far more accurate than
accel tests for jetting work.
• Typically, for every 100 RPM change in acceleration rate, you lose approximately 2-3
lb-ft of torque. Most circle track teams test at 100 RPM acceleration rates. Drag racers
use 300 or 600 RPM rates.
• The best way to measure A/F ratio is through the use of O2 sensors. Hendrick
Engines uses 10, one in each header tube and one in each collector.
• The Air Turbine must be on straight and sealed to get repeatable results.