Can't think of any Pontiac performance engines after the mid 60's that came with what the Engine Master guys called the "stock fan" that caused the 30 horsepower loss. The clutch fan's 14 horsepower loss sounds about right.
The shroud would cost horsepower because it does what it is supposed to do - help the fan pull more air through the radiator. More air pulled requires additional horsepower, but it accomplishes why we have the fan in the first place which is to draw more cooling air past the radiator fins.
My non-air '67 HO did not come with a shroud, but was less than two weeks old when I went down to the dealership and purchased one to combat the temps I was seeing when stuck in summer traffic. While it dropped idle temps down by close to 20°, it did raise running temps blasting down the freeway by about 5°.
They didn't mention that the flow of air going through the radiator at speed would greatly reduce horsepower loss from the fan since it would be at or close to a neutral pull.
__________________
Mick Batson
1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress.
|