Opening up hood vents

[sms2022]

I started to design a set of hood vents. Hopefully they will be easier to install.

My plan is to cut the hood openings larger to match the opening in the vents once the plastic drip trays are removed. This will be virtually unnoticeable to the untrained eye if done correctly with the stock vents in place.

Hood blanket will be cut on three sides around the vents, leaving the rear in place so it can fold. I will come up with a system to pin it back to expose the opening or forwards to cover it (cold weather driving).

Plan for the new vents is to take the grilles out and make the drip tray easily removable. Will also cut access holes in the hood blanket for bolt access.

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[Snakebyte]

@NightmareMoon your video makes me wonder if just the side vents are adequate for track days, and skipping the big center vent.

Interesting also is how the yarn in front of the windshield folds forward, leading credence to the claim that the high pressure zone there would render removing the rear hood edge gasket ineffective.

I performed a similar string test on my MP Concepts GT500 style hood, and got similar results for near the back extractor louver. (The front louvers did much better than the back louvers as well.) The back edge of the MP Concepts hood is a little bit further ahead of the windshield that some, generating a back louver neutral flow up to about 60mph.

That said, I since increased the size of my hood sheet metal opening increasing the airflow substantially out the extractor louvers.

Before:

After:

It worked...especially in stop and go traffic, there's evidence of success as I now observe significant wavy air currents billowing out the extractor at stop lights and on interstate stop and go situations. So, my reason for obtaining the GT500 style hood is working to my satisfaction.

Note that I also did not put insulation on the underside of the hood so that heat would transfer through the metal and radiate quicker into the atmosphere. Of course folks with similar CF material may have issues without insulation.

So back to your mention about the high pressure area...indeed as you stated there is a high pressure area in front of the windshield. In my early driving years about 1970 I recall numerous cars taking advantage of that high pressure area for cowl induction. The 1970 Chevelle SS 454 immediately comes to mind. Even NASCAR had an approved air intake location at the base of the windshield for stock cars...of course cars back then were more stock than they are today.

 

[WildHorse]

First off on a GT hood, those aren't heat extractors. They are positioned is such a manner that it'll do next to nothing for heat extraction. They're for pressure relief. GT350 hood, GT500, the center section is for heat extraction.

 

[MrMike]

Maybe I misunderstood some other threads, so please correct me if I'm misunderstanding and this was hyperbole.

I thought that the best way to go for airflow was an aftermarket GT500 hood or center race louvers. That way the air would go through the radiator and out center hood vents that were positioned far enough back.

 

[Paul McWhiskey]

Always keep in mind that no matter how big of a hole you have for air to enter, if it cannot get out there is no increase in airflow. This subject has been very well covered by A.J. Hartman and a few others.

There is a reason that the Ford engineers have designed the grills and front facia on these cars the way that they are. Unless modified, there is not much reason to change things. But, we are never happy with stock so we throw ourselves into these situations. For me, I will stay with those like A.J. Hartman and follow their well thought out, and backed by testing, lead.

 

[sms2022]

Always keep in mind that no matter how big of a hole you have for air to enter, if it cannot get out there is no increase in airflow. This subject has been very well covered by A.J. Hartman and a few others.

There is a reason that the Ford engineers have designed the grills and front facia on these cars the way that they are. Unless modified, there is not much reason to change things. But, we are never happy with stock so we throw ourselves into these situations. For me, I will stay with those like A.J. Hartman and follow their well thought out, and backed by testing, lead.

Completely agree. This is a hand in hand mod with the bullit grille from FP which has a lot more openings for air to flow through. I just want to neutralize that increased pressure which will have the added benefit of cycling more air and in turn heat from the engine bay at speed. How much? I don’t know, probably not much.

 

[Paul McWhiskey]

Completely agree. This is a hand in hand mod with the bullit grille from FP which has a lot more openings for air to flow through. I just want to neutralize that increased pressure which will have the added benefit of cycling more air and in turn heat from the engine bay at speed. How much? I don’t know, probably not much.

Gotcha! But without creating an avenue for the air in to get out there is no benefit. Many times, i think that we start from the wrong end of the problem.

 

[sms2022]

Gotcha! But without creating an avenue for the air in to get out there is no benefit. Many times, i think that we start from the wrong end of the problem.

Think we’re just speaking two different languages right now. If I cut the openings in the hood for the vents larger more air will flow out of those vents to counter the additional air flowing in from the grill. That’s my hope at least from observing the fog pass through the factory 1” hole in those vents.

 

[526 HRSE]

I mean you can always do a DIY project and install one of those spare AC vents laying around the house with some spray paint… +10hp

That's why they are MexiCANs and not MexiCANTS!

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