Options on making fake hood heat extractors functional

[2morrow]

I gutted the vent and cut out the underneath area on the bottom of the hood.

Shortly after I replaced those vents with aftermarket Carbon Fiber Roush style pieces.

Eventually I replaced everything with track spec units.

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[MrMike]

I gutted the vent and cut out the underneath area on the bottom of the hood.

Shortly after I replaced those vents with aftermarket Carbon Fiber Roush style pieces.

Eventually I replaced everything with track spec units.

Did the Roush style vents actually drop temps or were they just kind of a half measure?

I enjoyed your build thread, not many other Guard cars still around!

 

[WItoTX]

It's also not taking into account just sitting in traffic, slow driving etc. Heat is absolutely pouring out of my hood at all times, it's very easy to see it lol.

Mine does too LOL...But, with the SC right there, I suspect the size and placement of the GT500 vent is to help get heat out while just sitting or moving slowly, when air can't be pushed through the radiator and up through the vent, exactly as you point out.

 

[MCS]

This. Get a GT500 hood if you want heat extraction.

I'm so tempted to take mine back to the body shop and have them remove the rain tray and then reseal it back up. I never drive it during the rain anyways LOL although I do wash the car with a hose.

 

[tosha]

Ask and you shall receive....you see how all the strings lay flat on the back side of the middle vent? That means air isn't coming out. See how the strings in the front are pointed up in the air? That means air is flowing.

As you can see, the side vents move a hell of a lot more air than the middle vent while driving. And the back half of the middle vent does nothing. The GT500 vent is far larger than the vent in this picture. But as vaee said, it's menacing AF!

Here is a link to the full video. Credit to @NightmareMoon. AJ Hartman also has wind tunnel videos with a variety of hoods/vent combo's worth watching.

My experience with racelouver rx vent is different, all the ribbons are standing up in the center one. Likely this is due to different construction and efficiency of racelouver vs tracspec

I agree about GT500 vent in general. It seems to be designed more for heat dissipation on top of SC area, rather than to create negative pressure to pull heat from radiator.

 

[NightmareMoon]

The reason the big center vents are not as effective over their entire area is because of the location of the pressure area on the hood caused by the windscreen. The back half of the vent is getting into a higher pressure area.

The GT500 hood is a unique shape, and its a little domed. I'd guarantee its flowing more over the front part of it than the rear part of it, but you'd definitely want to look at it's aerodynamics as a little unique, because it is.


Anyway my testing showed that the Ford side vents on the 15-17 and 18" are located in fantastic places, assuming you open them up enough to flow well. Ford knew what it was doing.

 

[2morrow]

Did the Roush style vents actually drop temps or were they just kind of a half measure?

I enjoyed your build thread, not many other Guard cars still around!

I never had a temp issue with my car as the grill is open compared to OEM. I run at Thunder Hill a lot and it get crazy hot up there. I’ve never had an issue though with the mods I have.

My goal with the CF units (Sigala made but look similar to roush with bigger openings) was to move the air out of the hood. Apparently it works because one day coming down the straight one of the vents blew off and flew 20’ straight up in the air. Like straight up. After that I went with the track spec units.

Note that my center vent is moved forward compared to their suggested placement to catch all the air after the radiator shroud, not over the engine. One forum member noticed the lack of flow in the original placement and that was my original concern so I forward mounted mine.

Lastly, thank you on your comment. It’s a fun car and I like how the color is unique to a degree. I’ve been tossing the idea of a wrap but haven’t done it yet.

Stay safe out there and enjoy the ride!

 

[DopamineQuest]

I'm so tempted to take mine back to the body shop and have them remove the rain tray and then reseal it back up. I never drive it during the rain anyways LOL although I do wash the car with a hose.

Lol this is what I do when I wash it. Totally unnecessary I assume, but it makes me feel better damnit!

 

[WItoTX]

My experience with racelouver rx vent is different, all the ribbons are standing up in the center one. Likely this is due to different construction and efficiency of racelouver vs tracspec

I agree about GT500 vent in general. It seems to be designed more for heat dissipation on top of SC area, rather than to create negative pressure to pull heat from radiator.

Funny enough, I almost used your post as the reference, until I looked at the gurney effect on yours. It appears only your last vent is flush with the hood. I don't think these vents are comparable to the generally flush mount GT 500 vents. Also they are quite a bit shorter, and further forward on the hood (As pointed out by someone else) right in the low pressure zone.

These were the vents I plan to go with at some point, and stick a gurney in front of the whole thing.

 

[Ewheels]

OP, cut your hood....you know you want to!

Racelouvers are well documented to be the best in the business and they have actual wind tunnel data to back that up.

 

[tosha]

Funny enough, I almost used your post as the reference, until I looked at the gurney effect on yours. It appears only your last vent is flush with the hood. I don't think these vents are comparable to the generally flush mount GT 500 vents. Also they are quite a bit shorter, and further forward on the hood (As pointed out by someone else) right in the low pressure zone.

These were the vents I plan to go with at some point, and stick a gurney in front of the whole thing.

I agree, the construction is completely different. Here's few more shots for better idea:

The gurneys on rx version are super aggressive:

 

[Paul McWhiskey]

After spending a lot of time on this I will be ordering Race Louvers for mine. I don’t particularly care for the bolt on look, but a buddy of mine who is a genius with sheet metal (he retired from Alaska Airlines) and I ( A&P but not anywhere as good with sheet metal) are going to install. He says that he has some ideas to make the final product look better. I will post up some photos when it’s finished.
Last weekend while coming over 50 from Carson CHT got to 232 degrees, it was 90-92 ambient, A/C on, 5th gear, 55mph. Oil temp got up to about 2/3’s of the green arc and stayed at 50lbs oil pressure. I am pretty sure the Race Louvers will help.

 

[MrMike]

Anyway my testing showed that the Ford side vents on the 15-17 and 18" are located in fantastic places, assuming you open them up enough to flow well. Ford knew what it was doing.

Yeah from your comment here and from others, sounds like letting more air out of the existing side vents is a viable option. Maybe the Roush style or other drop in replacements aren't too bad after all.

My goal with the CF units (Sigala made but look similar to roush with bigger openings) was to move the air out of the hood. Apparently it works because one day coming down the straight one of the vents blew off and flew 20’ straight up in the air. Like straight up. After that I went with the track spec units.

I bet that was both funny and embarrassing at the same time.

Looking at track spec's site they say it's a direct swap but also say "minor cutting of the hood is involved" for the side vents. How much cutting was really required?

 

[NightmareMoon]

Looking at track spec's site they say it's a direct swap but also say "minor cutting of the hood is involved" for the side vents. How much cutting was really required?

For the side vents - a lot . Its irreversible. The good news is for the side vents, all the cutting is to clear out the underhood 2nd skin metal which is in the way to get access to bolt the vents into the top skin of the hood. IIRC you don't have to cut anything which will end up visible from the top of the car so it wasn't very stressful (unlike cutting the hole for the big center vent)

 

[Paul McWhiskey]

Keep in mind that air that cannot get out means that air is not going to be coming in. Therefore, custom grills that are wide open, or cutting out a stock grill may only provide a small increase in airflow if at all. Allowing that air to exit the engine compartment and creating a bigger delta across the radiator and other coolers will make a difference.

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