Hood Vents
1990 928 S4

April 23, 2005

In an effort to get rid of more heat from the engine compartment (and increase air flow) I'm experimenting with some hood vents. Beth and Richard donated a hood off their crashed 928S:

The location of the slots were at point 9 on the chart below (but before 9.5). This is a low pressure area, which will suck air out of the engine compartment, but is also far enough back to let the air flow over the engine and to the firewall to create a high pressure area (of hot air) under the hood.

I took it to B & M Auto Body in Berkeley and had Bob cut some vent slots and paint it:

It didn't look too bad when he was done

Then Bill and I installed it:

I think it looks good, I'll have to see if it improves air flow through the engine compartment.

Thanks Beth, Richard, Bob, and Bill, also to Marc T for suggesting the location.

Update 04/04/2016

After adding the vent for the intercooler heat exchanger, I decided I wanted to use the same style louvers for the hood. I ordered a set of steel powdercoated air return vents from Home Depot and cut them to size.
Here is a trial fit:

I then taped the area and cut out a section of the hood, then glued and pop riveted them in place.

Here's all three vents:

This is a larger hole with more aerodynamic venting, so it should flow even more air.

Update 08/20/2016

To help remove some more heat from under the hood I decided to add another vent, this time behind the radiator on the passenger side. This has the hottest air flowing throught the radiator. I figured it would be good to let some of that air exit before hitting the rest of the engine bay.

Here is what it looks like from underneath after cutting and pop riveting the new vent in place:

And a look at the top:

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Copyright 2005, George A Suennen
written: 01/23/05
rev: 08/20/16