fan shroud ?

[rallystyle]

ok I am starting to shop for a radiator for my 69 camaro with a ls swap. i see some manufacturers are using a fabricated shroud that covers most of the back side of the radiator and some are using a plastic that have the pressure relief vents. what i am really trying to find out is at what point do you need the relief vents to help with cooling. i know the suck closed when the fan turns on to pull air from the radiator core for max cooling. but when your going down the road they allow more air through the core for cooling. at what point should you have them? if your radiator does not have them. can they be added ? to me it seams that the radiator is not being fully utilized if you have to force all the air out just where the fans are. any insight on this would help before i decided on my radiator order.

Thanks

[Vince@Meanstreets]

Originally Posted by rallystyle

ok I am starting to shop for a radiator for my 69 camaro with a ls swap. i see some manufacturers are using a fabricated shroud that covers most of the back side of the radiator and some are using a plastic that have the pressure relief vents. what i am really trying to find out is at what point do you need the relief vents to help with cooling. i know the suck closed when the fan turns on to pull air from the radiator core for max cooling. but when your going down the road they allow more air through the core for cooling. at what point should you have them? if your radiator does not have them. can they be added ? to me it seams that the radiator is not being fully utilized if you have to force all the air out just where the fans are. any insight on this would help before i decided on my radiator order.

Thanks

Yes, the flaps are to allow air flow when you are at speed. The theory is when you are driving down the road and the fan kicks on it can increase air resistance drag, alternator charge drag and decrease fuel economy.

Most believe it is unnecessary and the air flow through a not running fan is enough to cool the engine and keep the fans off.

[rallystyle]

thanks vince.

been shopping around trying to narrow down what to buy. i have not seen a oem with any vents like that so i didn't know it would make that big of a difference.

[Justin@EntropyRad]

As long as a quality fan is used, it can bypass the use of flaps/vents on the shroud.

Make sure you get a radiator that has enough cooling surface to to the job properly!