This could also be that the huge opening in the roof caused so much wind resistance
that you needed to push the engine harder to maintain the speed.

PerL
87 Syncro 112i

jim hayes wrote:

> Wife and I noticed that when we opened the sunroof on our '71 bus at 50mph, the
> Cylinder head gauge climbed 50 deg F in 2 minutes give or take...(if memory serves,
> depending on wind direction)
>
> >
> >  Gen Berg wrote about the the air flow on his bus and the differance the
> > vent widows and mirrors made in air pressure and vacuum when they where
> > open and closed they interrupted the air flow and made the cooling fan
> > less effeciant
>
> --
> Jim Hayes
>
> Pixelography: The marriage of silicon and silver.
> Images at http://www.jymis.com/~jimhayes