I agree with you concerning the high speed cooling under most circumstances but.... When I installed the shroud on my roadster it completely eliminated any low speed heating but it did raise the temp on the interstate. The shroud actually obstructs the air flow at 70 mph. Cooling Componants installs rubber flaps in the bottom of their shrouds to aid in the air flow at speed. I find that running the fan on mine has a surprizing effect. You would expect that the air pressure at 70 mph would eliminate any effect that the fan would have but that is not the case.
Usually high speed cooling is a matter of radiator size but air flow is always important.
Last edited by John long; 07-03-2013 at 09:30 PM.