I've been looking for some heat extractor hood vents that are specific to the R5X minis. Unable to find some that are specific to our hoods I had to come up with something of my own design. I could have gotten a set of generic vents that would have either layed on top of hood bracing or you need to cut it out. I am definitely not a fan of cutting out impact protection in the event of an accident. You wouldn't cut out your roll bar to go racing so why cut hood bracing for a vent? Using the underlying hood bracing as a template I designed three hood vents that are not going to harm anything in the event that heavy rain goes in them. One is located center of the hood over the air box and the other two are over the wheel liners and part of the strut towers.
I'm picking up what I hope to be the final renditions tomorrow. If there is interest I will have some made up and posted for sale here.
I'm of the opinion that a lot of problems with the mini engine is heat and heat soak. When I pulled out my water crossover pipe the end crumbled off as a result of heat damage. I cant say this will cure that problem but it will definitely help with the longevity of the engine if you have spirited runs. Not only should they reduce heat they will also reduce any under hood lift and allow the opening up the S model's scoop increasing the cooling effect.
Here are some pictures of the development of the vents.




















the blue hood is a trial fit hood nonS. I'm going to add a scoop to it and try running with it.

 

Very nice work! Laser cut it looks like? What CAD software are you using?

I like the design approach of working around the hood bracing - though the bracing layer is for panel stiffness, it won't do much for collision energy absorption. That's all in the design of the front chassis and the subframe. But keeping the bracing intact will keep the hood from becoming floppy and that's a good thing. Too bad you can't put the entire hood panel in the laser cut machine and just cut the metal that's already there.

 

Not sure you have them in a good place for full aerodynamic effect. Every aerodynamic diagram I have seen has the best place on the front of the bonnet.

I saw a diagram for these somewhere on a Miata forum. Can't remember which one and they declined to make some for the R53.
https://www.singularmotorsports.com/...-hood-louvers/

This dude did quite a lot of testing on his car and wrote some very good articles on testing and designing. He is a fellow Antipodean and I have had an American say the website didn't work for them.
http://www.autospeed.com/cms/article...art-1&A=113176

James

 

I'm not sure you quite understand the function of a heat extractor but the front of the bonnet would be the worst place to install a vent. Or I'm misunderstanding your description.

I spent a lot of time researching this and exactly how they work. Like everything in life there are always compromises. These are no exception. My criteria for the vents was 1, function 2, looks 3, protection of critical engine components 4, the actual hood structure itself. Function being the most important with the other 3 in differing order.

It definantly is not as simple as it seems to vent an engine compartment. Unerhood and outer hood pressures would need the be measured with a monometer to get perfect placement. So we would be looking for high pressure points under the bonnet and low pressure points on top of it. The areas with the largest differential of pressure would be the best location for vents. Since the high pressure would move to the low pressure side it would carry the heat with it. Doing this may put the vent over hood structure and it is part of collision protection of the vehicle. So it's off the table in my play book. The vent may end up looking terrible by placement, again a no no for me as form needs to follow function. It also my end up over critical engine parts another red flag. Although the car could be driven without a bonnet in the pouring rain and be perctly fine I'm not about to try it.
so back to my vents why they are where they are. Looks and function have been well thought out and I would not have done this if they would not have worked or looked good. For placement we are looking for known high and low pressure zones on any vehicle. So vertical surfaces would be high pressure and points directly behind them would naturally be low pressure. The frontal area of the car is a high pressure and behind that low. The headlight sticking up a bit higher adds to this pressure so directly behind them would be low. This eara also has the least hood structure and the least sensitive parts under it. It also looks nice. This spot is the most sensible placement of the vents.
the vent iive placed center and nearer the cowl is a difficult placement. This is in front of the windshield and the start of its high pressure area. For this one I've added a wicker that will create an artificial high pressure point in front of the vent. Since this is directly behind the S model scoop it may not be a requirement. Aesthetically they look great and add some really nice costomizing mods to the car. I will post pictures later today of what I hope to be the final product.

 

Does a non S hood fit on an S model car?

 

The MINI Goodwood is an S with a non S hood. Not sure if anything else is different to make it fit though.

 

I understand you thinking that, but I have done lots of reading on it. Haven't actually measured my R53, I can't find a cheap manometer to get sent over here.

These are the type of diagrams I have used to form my opinion of where the vents should be.


See the low pressure pressure zone just at the front of the hood where the air has to change direction? That is the best point for a vent as long as that point is behind your radiator. The lowest pressure on the outside of the car, and just behind the radiator where you want the hot air to exhaust from. It may or may not be the highest pressure point inside the engine bay, especially considering we have a top mount IC, but lowering the pressure there means you radiator (and AC condenser) work the most efficiently. This also correlates to anecdotal pressure measurements I have seen done by people (including Autospeed above). Here is the Flyin' Miata pdf I have seen before.

https://www.flyinmiata.com/support/i...sc/louvers.pdf

You will notice the NC hood has the point of lowest pressure out to the side similar to where you have your vents, but much further forward. Without knowing the pressure data for our specific car it is just a guess whether your vents are too long along the ridge of the hood and will just stagnate as the high pressure air from the back travels forward and gets sucked out again.

I agree with squawSkiBum, the hood structure is for panel stiffness and rigidity, not for crash protection. The hood folds, so there is no crumple zone for energy absorption.

Don't get me wrong, you are making an excellent product! I personally think you aren't doing the work needed to ensure it actually works at speed. It will definitely work when stopped at traffic lights, the Miata guys say they can see the heat roiling out of the vents when stopped, but there were a few early types that actually made their overheating issue worse on the test I read.

Take from this what you will. I freely admit I am not a professional in this field, and have no practical knowledge of my own. I have formed my opinions by reading a lot of anecdotal articles that look like they use good scientific methods, and by looking at how car manufacturers and professional race teams set up their vehicles.

James

 

Take that spare hood, draw a grid on it, drill a bunch of holes, wire up some pressure sensors and go out for a drive to get some data! The one thing I have learned is that if you look at a shape and think you understand intuitively how the air flows around it, you're most likely wrong. And the high and low pressure areas will move depending on speed. I wish I had a small wind tunnel available.

I like your thinking - just need some data to make sure you're putting the vents in the right places.

 

Just an fyi a folding hood is a crumple zone. I'd had my share of accidents and dont want to test this again LOL. I hear what everyone is saying and since I'm still in the build stage of the actual car and its winter there's not much chance of me driving around with tufts of wool taped to the hood. I have done some studies on fluid dynamics. Air is part of that theory and its reaction to other forces is all related. I am no expert either though.
I just want a cool looking car that's quick and like a gokart. I also have done enough research in these cars that heat and heat soak seems to be a big problem. I honestly can't think of a better spot to put the vents that will also be ..... well cool looking. I may be way off track on this but it's not often that I do that at this stage of my life (getting farting old). I do sometimes go overboard and the vents are just the tip of the iceberg of what I'm doing with that spare hood. It's getting a big scoop and inside the scoop will reside a 15 row engine oil cooler. Half the frontal area of the scoop will be deflected to the engine front just past the rad and the other half directed to the oil cooler. From the cooler it will be directed under the hood and out the rear vent. So the rear vent will just be for engine oil cooling. Like I said a bit overkill.

 

I'm thinking of selling these for 120 or so once testing is done. If someone here wants a set to test for me, I will sell to them for $60 plus shipping. If they need a revision or two I will send them free plus shipping. I'm still in the build stage with my car so I won't have time for actual road tests for a while. Plus some extra input can only help.
please PM me if interested. Regards Clovis

 

did you ever get these made?

 

+1 to "did you ever get these made?"

I have a feeling I'm local to you as well lol...