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Not exactly that easy. The miata has studs coming down from the hood, not bolts as most cars do. So you can add a spacer, but not much of one before you run out of threads.
The kits that are sold are simply a bolt extender that screws onto the stud, then another bolt attaches the hood hinge to that. The parts are of course metric, and hard to come across at your local hardware chain store.
 

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But it screws up air flow through the rad as it pressurizes the engine bay
 

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Well, my car last summer had overheat issues when idling in traffic. Changed out radiator, flushed the block, new fluids, checked line, still overheats in traffic. After the hood risers, no more overheat. I understand all the high/low air pressure talk but the bottom line is that when I'm sitting in a 100+degrees freeway jam, the risers help hot air escape, and that's good enough for me. And until I overheat at highway speeds, I'm going to assume that it's not "scewing up the airflow" enough to make any difference.

An added bonus is that the raised hood allowed me to modified the air intake on my turbo so that it's directly behind the radiator, there's even room for an over-the-radiator intercooler pipe set-up in the future.
 

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I've read about the same low-speed vs. high-speed effects ExHondaMan talks about. At low speeds it helps heat escape. At high-speeds air goes into the engine compartment. The amount of disruption at high-speed may or may not be significant. Some people have trouble at low speeds, others at high speeds, and some have no cooling troubles at all but if you live in a hot climate and have cooling system troubles that cannot be cured using other methods as described give it a shot. It's a cheap and easily reversible mod.
 

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I will agree that in stop and go traffic they will help heat escape from the engine bay.
 

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Just be careful when putting the risers on. Since our hoods are aluminum, I ended up slightly bending the hood on the passenger side and couldn't get the hood exactly realigned after taking the risers off. #-o
 

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That's the one good thing about my heavy ass steel hood. Once I 'upgrade' to a stock aluminum one, I plan to remove my hood risers.
 

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Hood Risers do not let hot air out.

They let air into the engine bay. The area in front of the windshield is a high preasure area.



Read this thread from MiataTurbo and follow the links

http://www.miataturbo.net/forums/showthread.php?t=9485



I don't buy it at all. Though my hood rise is very minor. My real life experiences on track to me prove that it not only helps cooling at low speed, but does not hurt at all at high speed. Though I feel it fair to say that I also have 2 small rear facing gills cut directly above the turbo to help let some more heat out.
 

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I'll grab some tonight if I remember.

One day when I get around to it I might also cut some of the hood structure beams to open them up more, but I'm not sure they are necessary, since stuff doesn't melt anymore, I can already see a good amount of heat waves coming out of them just at idle on a cold day, and the IR pyrometer shows that there is definately alot of heat coming out of them at idle.
 

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Hood Risers do not let hot air out.

They let air into the engine bay. The area in front of the windshield is a high preasure area.



Read this thread from MiataTurbo and follow the links

http://www.miataturbo.net/forums/showthread.php?t=9485



I don't buy it at all. Though my hood rise is very minor. My real life experiences on track to me prove that it not only helps cooling at low speed, but does not hurt at all at high speed. Though I feel it fair to say that I also have 2 small rear facing gills cut directly above the turbo to help let some more heat out.
Then explain to me how a Randall Cowel Intake works?
 

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Then explain to me how a Randall Cowel Intake works?

I would not attempt to, or to try and convince you that a randall intake does or does not work. I have absolutely no experience with them.


All I can tell you is that my car at 6000ft elevation, with a $125 stock replacement brass radiator, 6 psi of boost, large starion IC, slight riser in the back of the hood, two small gills cut in the hood above the turbo, oil cooler behind both the radiator and IC, and no belly pan stays dead center on the stock temp gauge during 30 minute track sessions, and around town, though it's slow to warm up on cold mornings.

Also my drivers side headlight lid is slightly bent down at the back, as well I have the R pack front airdam.

Before the riser and gills I was overheating a little on track as well as melting stuff at stoplights, sorry I didn't test independantly as I did the gills and riser at the same time.

Without any serious windtunnel ($$$) testing on a loaded dyno which will never happen, I think detailed anecdotal evidence specifically to a miata is the best we can do. Take it for what it's worth, as it really doesn't matter to me if you believe me or not.
 

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OK then why did Mazda, who did do wind tunnel testing on the Miata put weather stripping to seal the bulkhead between the cowel and engine bay.

We all know that Mazda is 'cheap' and would not waste $ 5 on weather stripping if they did not have to.

By the way the Randall Cowel Intake works because of the positive air preasure in the cowel. (in front of the windshield).
 
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