under hood temperature management

[yevgenievich]

This was a relevant excerpt that I found posted by FellowTraveler:

"Past the radiator shroud to vent hot air and determined about a foot of that area after shroud is good for vent at all speeds except as noted the results were drivers side vented w/o problems at all speeds the passenger side pulled air in at all speeds the pulling in of air depends on rotation of cooling fan. Farther back @ center of hood the air vents at low speed and is pulled into the engine bay/bonnet at speed however this are is great for venting at lower speeds. The trailing edge of the hood/bonnet always pulls air in which is good for a sealed cowl intake to the 6.5td. I also have the area around the passenger side of the 6.5 busy w/IC/CAC pipes too which disrupts airflow on passenger side. All GMT400's have upper inner fender vents that vent at the area between the trailing edge of the fender and leading edge of the front door works somewhat but fender vents enhances the flow there and the turbo side will always flow out hotter air from under the hood/bonnet."

 

[yevgenievich]

Again, that will stagnate flow through the radiator. The more air you cram in behind the radiator, the less can flow through it as that pressure gets closer to what's in front of the radiator.

Was debating on idle/low speed benefit if offset by enough of flow at highway speed.

 

[Supercharged111]

Was debating on idle/low speed benefit if offset by enough of flow at highway speed.

Ahh, in that case I can't see it not helping.

 

[yevgenievich]

Two examples that were claimed to work with lowering under hood temp. I was thinking of similar to the green one, but bring down a bit.

 

[Schurkey]

Put a fookin' air dam under the radiator support, leave the hood alone.

You don't need rain/sleet/snow entering the engine compartment via the louvers.

You don't need unintended reverse-flow air depending on vehicle speed.

An air dam under the rad support increases pressure in front of the radiator and lowers pressure behind the radiator. This increases airflow through the radiator, and prevents waste air from interfering with heated engine compartment air blowing out under the vehicle.

The only downside to an air dam under the rad support is the possibility of increased driveline temperatures--which would tend to be cooled by the waste air coming under the rad support. Done properly, an air dam under the rad support can direct airflow into the front brakes. But the differentials may suffer in extreme-duty situations.

 

[Erik the Awful]

The idea of the ceramic coating is to keep the heat inside of the pipes so that's already working to your advantage and wrapping them will only shorten the life of the coating so not recommended. The header manufacturers say you will void the warranty if you wrap them as well so it obviously makes a big difference.

Engine Masters Episode 115 was a test of paint vs ceramic coating vs header wrap. Ceramic coating was worth less than a 10°F drop. Header wrap was actually effective, dropping the temperature 60°F.

The takeaway is that ceramic coating is for preserving your headers and making them look good. Header wrap is for heat management, but causes them to rust faster.

I agree with Schurkey on not cutting your hood. I cut a hole in my Jag's hood to get the hood scoop through, and now I can't park it outside. Any rain ends up pooling on the intake manifold and heads and eventually it ends up finding its way into the engine oil.

 

[yevgenievich]

I am ok with header wrap for heat management. Might be a good start. And for louvers, was thinking for them being on a side of the hood instead of middle. That way rain does not get directly on to the engine

 

[yevgenievich]

Still thinking of a snorkel as a way to get direct air for the engine from outside

 

[Frank Enstein]

Trays could be fabricated to divert rain from dousing anything important.

Stainless steel headers will tolerate being wrapped much longer than any other material except maybe Titanium.

Splitting the top edge of the fender and pulling the fender out at the back will absolutely evacuate the engine compartment especially at speed.

The grille area is best for stuffing air into the engine followed closely by the cowl area.
Mounting the snorkel closer to the ground is a great way to make the air cleaner dirty fast. Same with the grille area.
That is why cowl induction is often a first choice.
I agree with Shurkey on the air dam. A simple flat plate at the radiator core support (better with a forward facing lip) will increase pressure in front of the rad but more importantly create a low pressure area behind it.

Yarn tufts are your friend!

There is a book by Forbes Aird that has a bunch of good ideas that will help.

You must be registered for see images attach

It's out of print so get a used one.

 

[Supercharged111]

Am I the only snob who parks his truck (dually) inside?