Shopping Cart -

Your cart is currently empty.
Continue Shopping
This website use cookies and similar technologies to improve the site and to provide customised content and advertising. By using this site, you agree to this use. To learn more, including how to change your cookie settings, please view our Cookie Policy
Pocketmags Digital Magazines
CA
Pocketmags Digital Magazines
   You are currently viewing the Canada version of the site.
Would you like to switch to your local site?
Digital Subscriptions > Diesel World > January 2019 > Q&A

Q&A

DIESEL WORLD MAGAZINE

COWL INDUCTION HOODS

Can you explain how a hood’s cowl induction, not directly connected to air intake, can affect the air pressure inside engine bay, which according to what I’ve read could affect engine cooling? I’ve also heard that cowl induction could slow the flow of air entering through the grille area. I would think that if the air enters through the grille and exits through the hood and/or through the open bottom of the engine bay it would not cause heating issues, compared to just exiting through the bottom of the engine bay without cowl induction?

James North Via Email

Good question. Here’s a theory. Airflow through the cooling stack (ATF cooler, A/C condenser, intercooler, radiator) is a result of a pressure differential—higher pressure ahead of the stack and lower pressure behind, either due to road speed or fan operation. Also, at speed, there’s a high-pressure area located at the lower edge of the windshield due the horizontal airflow across the hood stacking up against the windshield. This is why cabin ventilation inlet ducting exists at that location— it’s forced-air ventilation. This area of higher pressure will force air into the engine compartment via a cowl induction hood unless the cowl is sealed and is used to supply air only to the engine’s intake system.

So, any forced air entering the engine compartment, other than the cooling stack, can and will change the pressure differential and could likely reduce the amount of airflow through the airflow-resistant cooling stack. Because of the large areas surrounding the engine that allow for hot under-hood air to exit, no hot underhood air exits through the cowl hood because of the pressure differential that exists when the vehicle is moving at normal road speeds. Without the cooling stack (again, ATF cooler, A/C condenser, intercooler, radiator), airflow through the grille would overwhelm the cowl induction hood in terms of air forced into the engine compartment, but the stack makes it a lot harder for air to flow through even at highway speeds… whereas open-cowl induction is pretty much a straight shot into the engine bay.

READ MORE
Purchase options below
Find the complete article and many more in this issue of Diesel World - January 2019
If you own the issue, Login to read the full article now.
Single Issue - January 2019
$9.99
Or 999 points
Annual Digital Subscription
Only $ 1.75 per issue
SAVE
82%
$20.99
Or 2099 points

View Issues

About Diesel World

Diesel World January 2019, VINTAGE MODERN: DMAX’D 1958 CHEVROLET, NATIONWIDE EVENT COVERAGE – INSIDE!!, And More.......