Furnace blower motor RPMs modified... is faster ok?

Ductape wrote:
And it will change your air to fuel ratio. I would bite the bullet and replace the entire furnace.

How so? The burner and firebox is seperate from the room air blower and has nothing to do with blower speed or air.

I'd go with the faster motor and not be concerned. Corrosion issues are from sitting over years, not from running. At operating temp the firebox HX is plenty hot enough to burn off any condensation.