Type-R has an Dual OverHead Cam (DOHC) where as the 1.8 has a Single OverHead Cam (SOHC). There's quite a difference i believe between the two.You guys are wrong the 1.8 does have true VTEC.
VTEC (Variable Valve Timing and Lift Electronic Control) is a Valvetrain - Wikipedia, the free encyclopedia system developed by Honda - Wikipedia, the free encyclopedia to improve the volumetric efficiency of a four-stroke Internal combustion engine - Wikipedia, the free encyclopedia. The VTEC system uses two camshaft profiles and hydraulically selects between profiles. It was invented by Honda engineer Ikuo Kajitani, and was the first system of its kind.
I have never read anywhere that it states that only Type R has VTEC.
But in general you could say the 1.8 has VTEC as it has 'lobes' on that cam which get activated in the eco mode. Its just not used to improve power output but rather to minimize pumping losses. So in fact its an eco-vtec vs the much better known performance vtec.
As for the OP's question, i've seen dyno runs from a forum member where he first did a run with the ac on full and a second with ac off. Power outputs were virtually the same upto around 5000 rpm. With the ac on full it reduced power by 10 BHP. So if you're flooring it just when the ac is drawing power, i think you would notice it.
Under no circumstance would it be the lobes switching at 5500 rpm, anything above 3500 rpm (regardless of throttle position) you will be running on the normal cam.