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It usually works good in stop and go traffic and in general at lower speeds.
In higher speeds the extractor hoods are better...and more expensive :)
 

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/\/\

agreed. If you have overheating issues at idle, then this is the perfect mod for you.

If you have overheating issues while driving at higher rates of speed (over 45 mi/hr) these spacers actually have the reverse effect on cooling. air actually goes into the engine bay at the base of the windshield lessening the pressure differential behind the radiator.
 
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Matt [exz3owner said:
@ Fri Sep 15, 2006 4:30 pm]/\/\

agreed. If you have overheating issues at idle, then this is the perfect mod for you.

If you have overheating issues while driving at higher rates of speed (over 45 mi/hr) these spacers actually have the reverse effect on cooling. air actually goes into the engine bay at the base of the windshield lessening the pressure differential behind the radiator.
I disagree, Matt.

For us mere mortals who drive our cars primarily on public streets, this setup allows heat to escape the engine bay rather than soak the engine when resting at stop lights. While driving at speed, the high pressure zone at the base of the windshield forces heat out the raised side corners of the hood.
 

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Matt [exz3owner said:
@ Fri Sep 15, 2006 4:30 pm]/\/\

agreed. If you have overheating issues at idle, then this is the perfect mod for you.

If you have overheating issues while driving at higher rates of speed (over 45 mi/hr) these spacers actually have the reverse effect on cooling. air actually goes into the engine bay at the base of the windshield lessening the pressure differential behind the radiator.
I disagree, Matt.

For us mere mortals who drive our cars primarily on public streets, this setup allows heat to escape the engine bay rather than soak the engine when resting at stop lights. While driving at speed, the high pressure zone at the base of the windshield forces heat out the raised side corners of the hood.
ok. I'll only say one more thing about this to keep this respectful. Physics applies to road going cars as well as race cars.

I will conceed that depending on where you placed your filter, this could effect air intake charge temps. And if you don't experience overheating while driving, then this may not be harmful. My biggest point is this is not a mod to combat overheating.

If you are having overheating issues, then you need to address what makes the most difference in cooling your engine. Is that radiating heat trapped in your engine bay? Or the factory heat exchangers like your radiator? This mod hurts the effeciency of your radiator. I'm not arguing that the raisers don't let some air our the sides or corners. But it lets more air in that it lets out. This lessens the pressure differential across the radiator. If you don't believe me, tape strips of yarn to the base of your hood and go for a drive. The mass majority of them will be sucked into the engine bay. Not pushed out. I've done this admittedly not on a miata, but on other cars with this result. If your car is having overheating issues, then you need to address things that effect water and oil temp.

But to each thier own. If you like the style, and can come up with a reason for why it benefits you, go for it. People on m.net were saying things like this to me about wings for a long time before I proved them wrong. So I can appreciate you attempting to experiment with something outside the mainstream. Good luck.

Matt
 
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I believe it's commonly understood that the hood riser kit is not intended to repair abnormal overheating issues, but rather to minimize the inevitable phenomenon of engine heat soak and underhood temperatures on otherwise properly functioning cars.

I would welcome a scientific comparison test so we can put this matter to rest, one way or the other.
 

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i think if you're in the market for something that increases your cooling system's efficiency, a hood with a drop vent would be much more effective than these hoodrisers. granted the hood will cost you $500-700, as opposed to $10 for a set of coupler nuts, if you're going for efficiency, i'm sure you won't be cutting corners =]
 

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i'm curios about lifting hood too. so if at speed, air flow thru radiator should eventually escape down the bottom,right? now with a raised hood,at speeds, wouldn't the bypassing air flowing over the windshield only vacuum out the air from the engine... its the same idea as those reverse vented hood scoops on EVOs.
 

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anyone who has access to shop air and a smoke machine should test this out. really! get a cigarette, a small fan, shop air or air nozzle.
test subject EVO9. blow smoke into engine and air over the top and see if smoke gets vacuumed out. if it doesn't... than what does that tell us about the engineering behind the hood on a EVO9???? hood ornament?
 

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i'm curios about lifting hood too. so if at speed, air flow thru radiator should eventually escape down the bottom,right? now with a raised hood,at speeds, wouldn't the bypassing air flowing over the windshield only vacuum out the air from the engine... its the same idea as those reverse vented hood scoops on EVOs.
The difference here is that the pressure changes over the hood. THe evo vents are in the middle which is a low pressure area so it vaccums the air out of the engine. as you approach the windshrild the pressure increases, so where the hood riser is open you have a lot of high pressure air trying to force it's way in.
 
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