Intake Design Exploration

[scotty305]

Additionally, you might want to think about how you're going to test your setup. It seems it would be wise to use realistic ramp rates on the dyno (if the dyno software allows for this).

I fully appreciate the benefits of step testing with sweep testing at the actual rate of acceleration of the vehicle. This can show completely different issues, and allow the separate tuning of load/rpm tables from acceleration enrichment. It can also help to separate engine loads from drivetrain rotating mass loads - both of which alter tuning requirements (both fuel/spark for engine management and pulse tuning in intake and exhaust systems).

An example of different results - Using step testing, I can develop a plenum where a specific volume shows a very nice improvement in output at higher rpm over a 1000 rpm window of the power band - without hurting low rpm output. However a sweep test will show a tendency to hurt lower rpm response and not influence upper rpm output nearly as much as the step test. On the track, this plenum causes the engine to be lazy with poor transient response. And a plenum 20%-30% smaller is actually considerably quicker and faster on the track - dyno results be d@mned.

The same things hold true in exhaust design.


All that matters is the track or street results - RIGHT?
Dyno results (HP/TQ numbers) are irrelevant other than for impressing uninformed customers, internet bragging rights, and the Engine Masters Challenge. They don't win races.

IMHO, both step and sweep testing need to be performed together. And all atmospheric conditions need to be taken, and corrected for, at the point of air entry into the vehicle.

this is about actual results using several types of testing methods on both engine and chassis dynos, and comparing the results to actual performance on road or track, not theory.

On a quick accelerating vehicle, intake and exhaust pulse tuning does not have the same time to stabilize as it would with a step test spending 6-8 seconds at each rpm point. The difference can be very large. This is a well understood issue. Perform your own testing and see the results for yourself.

There is a big difference between tuning being "fine" and being right. To engine builders, racers, and customers trying to get the best results for their hard earned Dollar, this matters.

info from http://www.efi101.com/forum/viewtopic.php?t=4105