<VV> Mo' Fanz

[Padgett]

>  Anything you can do to cool the manifolds
>off will cool the heads, and exposure to 70 MPH ambient air certainly
>qualifies.
>  Further, the lower shrouds do reduce total airflow over the
>engine, which would obviously raise head temperature as well.

Thought that was what I said - the lower shrouds cut the airflow and the 
high pressure area under the car does exactly that. Wonder how much the 
every increasing chin spoiler size was to reduce lift and how much to 
improve cooling ?

>  GM needed
>the bottom of the engine to stay fairly hot in order to provide heat and
>defrost once the gasoline heater became optional.  Likewise, it's pretty
>clear that they decided that normal operating head temps below 475 F were
>acceptable, so who cared if the heads were at 450 instead of 400?

GM also considers excursions to 220F-230F in a modern car to be acceptable. 
I do not and run mine at 179F-188F. Just about everything under the hood 
lasts longer. Of course our "new" car is a 1992 and oldest (today) is a 
1970 so tend to keep cars somewhat past their expiration date.

Suspect that it might be interesting to take a set of lower shrouds and 
install a second set of passages on the leading edges. With the right 
shaping it should act as an extractor to boost cooling flow but be able to 
remain closed for heat.

This also raises the question of whether the plenium pressure is needed for 
cooling or for air flow to the heater. Do deflashed engines have as much 
heat - anyone know ?

Something that has always fascinated me is the way a fairly narrow range of 
temperatures have such a seemingly large effect on engines. Almost no-one 
has trouble at 75F yet add just 20F and things go wonkey. Control of 
temperature is one of the areas I concentrate on in our cars and have ever 
since I learned the Carnot and Otto cycles and believe that a properly 
controlled engine will run cooler and more efficiently than one that is not 
(power relates to the area enclosed by the curve. Dropping the bottom is as 
beneficial as raising the top). Being able to concentrate on this one 
aspect is an advantage I have over the GM engineers who operate under many 
more design constraints.

Padgett