How much does the airbox take off the idle speed?

[cleverusername]

I have the Sprint engine tuned to idle at 800rpm steadily without the airbox and filter on. Do I need to turn up the idle speed a bit to compensate for the restricted airflow through the filter before refitting the airbox or will it have little effect?

[soe8m]

It does have some effect on idle speed fitting the airbox. The mixture slightly changes affecting the revs. Even open or closed bonnet does alter the idle speed slightly because of heat difference.

I never measured but I guess it's in the range of 50 - 100 rpm.

Jeroen