The highly lame: Hood "Risers"
08-08-2011, 01:58 AM
#1
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The highly lame: Hood "Risers"
Okay, so i've searched decent amount of topics here, and while I have no need to fix a current temperature problem, The science somewhat interests me, and the topic is always debatable amongst my friends.
As the topic says..
On MY Car, 1990 miata, with all a stock hood, and vented turn signals,
1. car running, say over 40mph
a. air comes in thru vents? sucked in due to pressure
b. would air come out and "vent"
2. car idling, 0 mph
a. hot air does come from engine bay, and onto windshield u can see, but, theres no pressure then correct?
some claim it vents, some claim good temp decreases, some say stupid "CR.net ****", like I said, not interested in doing it, i'm just wanting what you think about it, thanks
As the topic says..
On MY Car, 1990 miata, with all a stock hood, and vented turn signals,
1. car running, say over 40mph
a. air comes in thru vents? sucked in due to pressure
b. would air come out and "vent"
2. car idling, 0 mph
a. hot air does come from engine bay, and onto windshield u can see, but, theres no pressure then correct?
some claim it vents, some claim good temp decreases, some say stupid "CR.net ****", like I said, not interested in doing it, i'm just wanting what you think about it, thanks
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08-08-2011, 02:15 AM
#2
Okay, so i've searched decent amount of topics here, and while I have no need to fix a current temperature problem, The science somewhat interests me, and the topic is always debatable amongst my friends.
As the topic says..
On MY Car, 1990 miata, with all a stock hood, and vented turn signals,
1. car running, say over 40mph
a. air comes in thru vents? sucked in due to pressure
b. would air come out and "vent"
2. car idling, 0 mph
a. hot air does come from engine bay, and onto windshield u can see, but, theres no pressure then correct?
some claim it vents, some claim good temp decreases, some say stupid "CR.net ****", like I said, not interested in doing it, i'm just wanting what you think about it, thanks
As the topic says..
On MY Car, 1990 miata, with all a stock hood, and vented turn signals,
1. car running, say over 40mph
a. air comes in thru vents? sucked in due to pressure
b. would air come out and "vent"
2. car idling, 0 mph
a. hot air does come from engine bay, and onto windshield u can see, but, theres no pressure then correct?
some claim it vents, some claim good temp decreases, some say stupid "CR.net ****", like I said, not interested in doing it, i'm just wanting what you think about it, thanks
There is no 'highly debated' topic here. At speed, the windshield is a high pressure zone. Raising the rear of your hood simply raises the pressure in your engine bay reducing the effectiveness of your radiator.
At idle, there would be no pressure, but if your car is overheating at idle, you have other issues.
If you would be willing to spend time and/or money on a "performance enhancement" that would only provide a marginal effect at best, and only at idle, while actually REDUCING the performance of your car AT SPEED, then you're priorities are *** backwards. (Note: not YOU, you. The hypothetical 'you' )
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08-08-2011, 02:17 AM
#3
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Wtf, who debates this still? The area behind the hood is high pressure at speed, lifting the back of the hood will increase engine bay pressure and decrease cooling ability.
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08-08-2011, 11:38 AM
#7
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But I run a slightly elevated hood (bent), cut short rubber trim (about a foot removed from driver's side), and no splash shield on my car and my rad. fans don't turn on often.
Why? the cut rubber hood trim was an attempt to get the pressurized cowl air to the turbo area so my hood paint wouldn't turn brown, and I'm too lazy to install the splash tray, and I don't track my car, and I have a coolant reroute, and I have a slightly larger aftermarket automatic replacement radiator. My "big" intercooler is a tube/fin too so more air gets thru it.
Why? the cut rubber hood trim was an attempt to get the pressurized cowl air to the turbo area so my hood paint wouldn't turn brown, and I'm too lazy to install the splash tray, and I don't track my car, and I have a coolant reroute, and I have a slightly larger aftermarket automatic replacement radiator. My "big" intercooler is a tube/fin too so more air gets thru it.
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08-08-2011, 01:20 PM
#15
don't care what you guys say. i bought some risers for $5 put them on in 4mins. and it definitely let heat out. in s. tx. traffic, while cruising, and at speed. yes that is a high pressure area in the center 12-18 inches. air does flow "in" a little in the center, stagnant near each end of those center 18", but flows "out" from under the remainder of the hood on each side. It was fine until i got a drop vent hood about a year later. only downside was i think it looks ugly, like your car was in a wreck, and everybody and their mama tells you your hood is open! it's not a vette 
might not be a big deal in cali. or michigan, but in south texas it gets stupid hot. and i've had to replace a ton of my brittle underhood wiring from it.
that was on my way to a pca event in the rio grand valley. i did put yarn all the way across the hood too see what it did at the track, but didn't get any video of it. like i've told other people though, ymmv. i had a splitter, and big hitler stache cutout on my bumper. not sure if that made it work better for me.
might not be a big deal in cali. or michigan, but in south texas it gets stupid hot. and i've had to replace a ton of my brittle underhood wiring from it.
that was on my way to a pca event in the rio grand valley. i did put yarn all the way across the hood too see what it did at the track, but didn't get any video of it. like i've told other people though, ymmv. i had a splitter, and big hitler stache cutout on my bumper. not sure if that made it work better for me.
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08-08-2011, 01:23 PM
#16
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I did the exact same test and my strings pull in at 40mph.
its a horrible vid, but at :06 i say "40 mph" and the inner string is sucked in and never lows back out. And that was just with the gasket pulled out.
anyways, who gives a flying **** how hot it is under the hood? If i move to TX I won't change a damn thing on my setup.
its a horrible vid, but at :06 i say "40 mph" and the inner string is sucked in and never lows back out. And that was just with the gasket pulled out.
anyways, who gives a flying **** how hot it is under the hood? If i move to TX I won't change a damn thing on my setup.
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08-08-2011, 01:24 PM
#17
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don't care what you guys say. i bought some risers for $5 put them on in 4mins. and it definitely let heat out. in s. tx. traffic, while cruising, and at speed. yes that is a high pressure area in the center 12-18 inches. air does flow "in" a little in the center, stagnant near each end of those center 18", but flows "out" from under the remainder of the hood on each side. It was fine until i got a drop vent hood about a year later. only downside was i think it looks ugly, like your car was in a wreck, and everybody and their mama tells you your hood is open! it's not a vette
might not be a big deal in cali. or michigan, but in south texas it gets stupid hot. and i've had to replace a ton of my brittle underhood wiring from it.
http://www.youtube.com/watch?v=ejPk2eBnr7o
that was on my way to a pca event in the rio grand valley. i did put yarn all the way across the hood too see what it did at the track, but didn't get any video of it. like i've told other people though, ymmv. i had a splitter, and big hitler stache cutout on my bumper. not sure if that made it work better for me.
might not be a big deal in cali. or michigan, but in south texas it gets stupid hot. and i've had to replace a ton of my brittle underhood wiring from it.
http://www.youtube.com/watch?v=ejPk2eBnr7o
that was on my way to a pca event in the rio grand valley. i did put yarn all the way across the hood too see what it did at the track, but didn't get any video of it. like i've told other people though, ymmv. i had a splitter, and big hitler stache cutout on my bumper. not sure if that made it work better for me.
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08-08-2011, 01:28 PM
#18
sad thing is many of them actually have better car control skills than 90% of the people hating on them. and atleast they are doing something with their cars besides hardparking them. what pisses me off is someone with a built motor, big power, and their tach has never swung past 4k. hardparkers/showcars don't need internals to look good in a parking lot. if you got it, use it!
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08-08-2011, 01:43 PM
#20
I did the exact same test and my strings pull in at 40mph.
its a horrible vid, but at :06 i say "40 mph" and the inner string is sucked in and never lows back out. And that was just with the gasket pulled out.
http://www.youtube.com/watch?v=aF-UPdfHEzU
anyways, who gives a flying **** how hot it is under the hood? If i move to TX I won't change a damn thing on my setup.
its a horrible vid, but at :06 i say "40 mph" and the inner string is sucked in and never lows back out. And that was just with the gasket pulled out.
http://www.youtube.com/watch?v=aF-UPdfHEzU
anyways, who gives a flying **** how hot it is under the hood? If i move to TX I won't change a damn thing on my setup.
i replaced my IAT wire 2yrs. ago. the wire broke inside the insulation causing my car to cut out under boost, and only after warming up. during a 15min. drive or longer, the isulation would soften/relax and the broken wire would separate. once it cooled the insulator would contract, making the wire reconnect again. this weekend, it did the same thing at the track, killing my session. extreme example, but thats one of the reasons why i care. but then again, if you don't track your car in 105*+ weather every year, it might not be that important to you. there's better ways to do this, like what i have now, but for the money and time involved it's not a bad short term solution.
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