Hood spacers
07-27-09, 05:49 PM
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Hood spacers
Some of the local rx7 guys were talking about hood spacers so I came up with these. Not sure If I'll keep them on my car as my hood is already vented.
07-27-09, 06:13 PM
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Not really sure, I don't really have a problem with cooling .... as I said my hood is already vented ... you can see one of the vents in the first picture. I know at the track for of the boingers that run the hood spacers see a small drop in ET's with them.
07-27-09, 06:18 PM
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Yeah, I'm sure if my hood wasn't venter they'd make way more of a difference. Sitting in traffic I can actually see the heat waves coming out of the passenger side vent.
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07-27-09, 06:20 PM
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It would to a certain degree, but honestly it's not going to be noticeable. The cowl is already a high pressure area which is why this works so well. Switching to a TII hood would actually be worse for your coefficient of drag.
07-27-09, 06:31 PM
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Cosmetics aside, from a performance standpoint is not pointless.
It's be proven for years that using the high pressure at the base of the wind screen has many positive effects. Ideally you want your intake to plumb into the cowl area (which a few OEM cars actually do) but if the goal is more airflow through the engine bay this is an simple way to accomplish it with little increase in drag. There are only two high pressure zones on a moving car that are appropriate for cooling. The front of the car and the cowl. The problem is if you increase the frontal area you increase drag. This is the exact reason cowl hoods work so well and why nascar cars all plumb their intake into the cowl. It's basically a free ram air effect.
Hood scoops may offer a benefit to cooling but they also increase frontal area and drag. Thats why the TII's have a higher coefficient of drag then the NA's. The ideal set up would be a naca duct, but those are not easy to make and they take away from engine bay space.
It's be proven for years that using the high pressure at the base of the wind screen has many positive effects. Ideally you want your intake to plumb into the cowl area (which a few OEM cars actually do) but if the goal is more airflow through the engine bay this is an simple way to accomplish it with little increase in drag. There are only two high pressure zones on a moving car that are appropriate for cooling. The front of the car and the cowl. The problem is if you increase the frontal area you increase drag. This is the exact reason cowl hoods work so well and why nascar cars all plumb their intake into the cowl. It's basically a free ram air effect.
Hood scoops may offer a benefit to cooling but they also increase frontal area and drag. Thats why the TII's have a higher coefficient of drag then the NA's. The ideal set up would be a naca duct, but those are not easy to make and they take away from engine bay space.
07-27-09, 07:27 PM
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I think it would look great. It's be a custom hood and you's have to be good with fiberglass or maybe metal working.
Here is a picture of them in an OEM application
Here is a picture of them in an OEM application
07-27-09, 07:36 PM
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Actually you wouldn't really want to cool the turbine housing. Hot exhaust gases have a higher velocity and are better for spooling the turbo. By cooling the housing and gases you'd spool up a bit slower. Now if you ceramic coated the housing and manifold you could then use the duct to help cool the downpipe and surrounding areas.
07-27-09, 07:53 PM
#16
learn something new everyday, thanks!
Actually you wouldn't really want to cool the turbine housing. Hot exhaust gases have a higher velocity and are better for spooling the turbo. By cooling the housing and gases you'd spool up a bit slower. Now if you ceramic coated the housing and manifold you could then use the duct to help cool the downpipe and surrounding areas.
07-27-09, 09:01 PM
#17
Raise hood?
Man as akward as it has become, Millions of Honda lovers have adopted this JDM look into their low quality cars. This has really become a Honda trademark for kids so I really started to dislike this idea of having your hood fit sloppy.
True for performance, but there is nothing better to me than a clean clean clean FC on the road.
True for performance, but there is nothing better to me than a clean clean clean FC on the road.
07-27-09, 09:22 PM
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Looks and style are very subjective. I personally prefer the hood to be flush, but that being said on the rare occasion when I do track my car, heat is a major problem both to reliability and performance so for the 5 minutes it takes to install these I'd do it. For me when it comes to performance it's always function over form. It's actually why I have a black hood. I found a blue aluminium one and didn't want to pay for paint, but really wanted the lighter hood. Flat black is slightly better then blue so a few rattle cans and now the car is 40lb lighter
I've seen a few cars where i actually liked the look of the raised hood. I think for me it was because the cars were ***** out drift cars and it wasn't done for appearance but because the cars were running hairy edge and needed every little tweak and advantage they could get. That to me is the definition of a high performance vehicle
I've seen a few cars where i actually liked the look of the raised hood. I think for me it was because the cars were ***** out drift cars and it wasn't done for appearance but because the cars were running hairy edge and needed every little tweak and advantage they could get. That to me is the definition of a high performance vehicle
07-28-09, 11:02 AM
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That is not a vent! It's an cowl intake...
If you go by theory, it will increase pressure in the engine bay (so behind the radiator) and decrease the amount of air passing through the radiator, hurting cooling performance.
Riz.
If you go by theory, it will increase pressure in the engine bay (so behind the radiator) and decrease the amount of air passing through the radiator, hurting cooling performance.
Riz.
07-28-09, 03:38 PM
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You make a good point about increasing the pressure in the engine bay, although it's not quite accurate. Hot air rises so at a standstill with the hood raised or vented the air can escape out of the back of the hood, helping prevent heat soak. At low speed the air will actually flow out of the rear of the hood allowing more air to pass through threw radiator due to less of a restriction. At higher speeds air is actually drawn/forced through the back of the hood and exits at the lower back of the engine bay. This actually creates a suction effect and helps pull air through the radiator, sort of the same way exhaust scavenging works. This also passes more air over the actual engine cooling the engine itself and not just the coolant.
High speeds are not much of a problem for cooling as there is plenty of airflow through the radiator. It's at idle and low speeds that the engine bay turns into a furnace. When I stop my car and let it sit for a few minutes, the vents in my hood get so hot that they will sometimes burn you. This is simply from the shear amount of ambient heat escaping through them.
I'm not saying a raised hood or hood vents are the end all and be all, simply sharing some of my personal experiences and knowledge I've gained from researching cooling efficiency. In my opinion nothing but good things are gained from allowing an engine to run cooler (but not to far below operating temps). You make more power, the oil breaks down slower and lubricates better, gaskets/seals last longer and electronics are less likely to melt/die. On most cars you don't need to worry about cooling, but the rotary is a beast like no other and the amount of heat it generates is mind boggling sometimes.....I have teh scars to prove it
07-28-09, 03:56 PM
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I feel like I am missing something? How would this be 'such a dangerous mod'? Please tell me people don't think this is more likely to make you hood fly off or open.
07-28-09, 04:00 PM
#24
When I said vent was referring to the ones in the center of my hood, see the picture below.
You make a good point about increasing the pressure in the engine bay, although it's not quite accurate. Hot air rises so at a standstill with the hood raised or vented the air can escape out of the back of the hood, helping prevent heat soak. At low speed the air will actually flow out of the rear of the hood allowing more air to pass through threw radiator due to less of a restriction. At higher speeds air is actually drawn/forced through the back of the hood and exits at the lower back of the engine bay. This actually creates a suction effect and helps pull air through the radiator, sort of the same way exhaust scavenging works. This also passes more air over the actual engine cooling the engine itself and not just the coolant.
High speeds are not much of a problem for cooling as there is plenty of airflow through the radiator. It's at idle and low speeds that the engine bay turns into a furnace. When I stop my car and let it sit for a few minutes, the vents in my hood get so hot that they will sometimes burn you. This is simply from the shear amount of ambient heat escaping through them.
I'm not saying a raised hood or hood vents are the end all and be all, simply sharing some of my personal experiences and knowledge I've gained from researching cooling efficiency. In my opinion nothing but good things are gained from allowing an engine to run cooler (but not to far below operating temps). You make more power, the oil breaks down slower and lubricates better, gaskets/seals last longer and electronics are less likely to melt/die. On most cars you don't need to worry about cooling, but the rotary is a beast like no other and the amount of heat it generates is mind boggling sometimes.....I have teh scars to prove it
You make a good point about increasing the pressure in the engine bay, although it's not quite accurate. Hot air rises so at a standstill with the hood raised or vented the air can escape out of the back of the hood, helping prevent heat soak. At low speed the air will actually flow out of the rear of the hood allowing more air to pass through threw radiator due to less of a restriction. At higher speeds air is actually drawn/forced through the back of the hood and exits at the lower back of the engine bay. This actually creates a suction effect and helps pull air through the radiator, sort of the same way exhaust scavenging works. This also passes more air over the actual engine cooling the engine itself and not just the coolant.
High speeds are not much of a problem for cooling as there is plenty of airflow through the radiator. It's at idle and low speeds that the engine bay turns into a furnace. When I stop my car and let it sit for a few minutes, the vents in my hood get so hot that they will sometimes burn you. This is simply from the shear amount of ambient heat escaping through them.
I'm not saying a raised hood or hood vents are the end all and be all, simply sharing some of my personal experiences and knowledge I've gained from researching cooling efficiency. In my opinion nothing but good things are gained from allowing an engine to run cooler (but not to far below operating temps). You make more power, the oil breaks down slower and lubricates better, gaskets/seals last longer and electronics are less likely to melt/die. On most cars you don't need to worry about cooling, but the rotary is a beast like no other and the amount of heat it generates is mind boggling sometimes.....I have teh scars to prove it
Airflow is all about positive and negative pressures, and each setup (speaking specifically of engine bays) is different. Belly pan or not, fan shourd or not, rear aluminum pan or not. No one mod will affect each car the same.
Tape some tell tales to it and go for a drive. Video tape it and post it up so there's no more debate about whats going in or coming out.
Of course you'll see heat rising out of the hood while stopped. You can see that without hood vents
I think its a neat idea, Aerodyne tried to make adjustable ones back in the day. But to me, it looks like some yahoo didn't know how to fit a panel. But I like neat ideas, top marks on that.
