The raised parts increase the low pressure above the opening. The Vette is overkill but the correct concept.

 

So which would be optimal: 1) Cut a couple of "H" shapes into the hood with the cross-bar of the "H" closer to the nose of the car. Bend the shorter tab up above the line of the hood and bend the longer tab down into the engine bay. or 2) Cut slim rectangles transversely into the hood without cutting a half inch in the middle which would make the downward plane of one louver the upward plane of the next (I think this is what genesplicer did). I guess I'm wondering whether a big opening is better than a few little ones. It's probably not that big a deal, but I was wondering.

 

If I did ducting, I would do something like this from the new C7. Chevy claims they stole it from the C6.R

How feasible is this with the miata?

 

With the radiator in an OEM position, almost impossible. If you start cutting sheetmetal at the front and move the radiator, it would work great.

 

Angle the radiator at maybe a 35 degree angle back toward the engine-just an idea.

 

Wouldn't that make it even more difficult?

 

The rad. would need to be angeled foreward at the top.

 

both of those should work well.

 

This. The back of the radiator needs to be ducted to the vent(s) in the hood. Leaning the radiator back would make this impossible.

 

This is my car. It's still a work in progress so I have not been able to test whether or not this gap works as intended. That said, all I had to do to make that gap was loosen the bolts on the hood and hinges and slide the hood back as far as it will go. It would be really easy for somebody to try this and do some tuft testing if they were so inclined. The positioning of the gap relative to the radiator, I expect, would have minimal impact on performance. The engine bay, as mentioned in the thread previously, is essentially a uniformly pressurized box. If that box has a hole in it, and the hole opens to a region of lower pressure, air will flow through that hole.

 

Anyone have observations on the heat rejection hood from Carbonmiata.com? I may buy a couple which would save on shipping. I hear that their quality is very good.

Full carbon variant. Looks like the vents are forward enough.

 

This one?



Total opening area on that hood is only ~50% of ideal. Placement of the vents is OK for the front two slots, not so great for the rear two - figure the rear two slots will only be marginally effective, reducing overall performance further below that 50%. That will also dump water on top of the valve cover when it rains.

Carbon Miata parts are nicely made though, good fit and finish.

-Ryan

 

I don't want water in my spark plug holes.
-guy who lives where it rains every day in the summer.

 

This should belay concerns about the valve cover. I think placement is good, but overall area may be small.

 

^ That NB version is safe from water, but correct on the opening area being minuscule.

-Ryan

 

But better than not having an opening, for sure! Massaging the openings might help if they don't prove effective enough.

 

Not necessarily. The rear openings will see positive pressure, potentially negating any gains from the front two. TBH it sounds like you're rationalizing the poor vent configuration because it's pretty. OEM hoods are really light. Only lighter hood I've ever seen are teh two vacuum formed dry carbon skins I got from Lightyear. Anything clamshell, wet layup like this one tends to be about the same weight as OEM or usually heavier.

 

everyone should just get singular hood louvers and be done with it

 

Evo vents?

 

OE vents are usually full of compromise, and it gets worse when they are grafted onto a car which has different airflow than the car they were intended for. The Ford GT500 vent in a Miata hood we tested? Our hood louvers doubled the performance over those. The Mini Cooper scoop in a Miata hood, same story.

We have an Evo coming in soon for venting improvements. Even the C7 Corvette - a car with some very good function-focused development behind it - we've improved the main hood vent by 30% on that car.



-Ryan