84' Cutlass pro touring build

Tony1968

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Jul 1, 2018
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I bought a set of these guys at a swap meet a while back that I’ll be using in my hood.
They came with the trays/covers, but one could just as easily use this to keep water out.
View attachment 211921

How well do your vents line up with the underhood structure? Any fitment issues?
The under hood structure on my hood is not like any I've ever seen. I'll get pictures once I mount hood. The vents are actually supposed to be a stronger structure once installed.
 
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Texas82GP

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Apr 3, 2015
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My little sister had a 93 Lumina Z34 with similar hood vents from the factory. It had little trays with drain hoses under each vent. That way, no matter if it rained or if you washed the car, no water got into the engine compartment.
 
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superbon54

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Apr 15, 2014
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I’m a fan of the open look btw. If you don’t plan to drive the car in the rain and have provisions to cover the vents if needed, my vote is run em wide open!
 
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scoti

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My little sister had a 93 Lumina Z34 with similar hood vents from the factory. It had little trays with drain hoses under each vent. That way, no matter if it rained or if you washed the car, no water got into the engine compartment.
This. Most hood openings from a factory perspective have drainage of some sort. To be clear, I'm not picking the choice apart; I'm asking to determine what others thoughts are on the matter and/or what they've done regarding the issue. I just know that water dripped/splashed on a detailed engine/engine compartment that's @ temp tends to not keep things looking quite so 'detailed'.
 
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Tony1968

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I’m a fan of the open look btw. If you don’t plan to drive the car in the rain and have provisions to cover the vents if needed, my vote is run em wide open!

This. Most hood openings from a factory perspective have drainage of some sort. To be clear, I'm not picking the choice apart; I'm asking to determine what others thoughts are on the matter and/or what they've done regarding the issue. I just know that water dripped/splashed on a detailed engine/engine compartment that's @ temp tends to not keep things looking quite so 'detailed'.
This is a nice weather car. Not even close to a daily driver. The purpose of the vents is to cool engine compartment and down force. Water intrusion is not something that concerns me at all. Appreciate all the opinions and keep em' coming.
 
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superbon54

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Apr 15, 2014
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This is a nice weather car. Not even close to a daily driver. The purpose of the vents is to cool engine compartment and down force. Water intrusion is not something that concerns me at all. Appreciate all the opinions and keep em' coming.
You and I have the same thoughts on hood vent function and execution.
 
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Streetbu

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May 22, 2011
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This is a nice weather car. Not even close to a daily driver. The purpose of the vents is to cool engine compartment and down force. Water intrusion is not something that concerns me at all. Appreciate all the opinions and keep em' coming.
Plus they just look badass Tony!
 
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Tony1968

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You and I have the same thoughts on hood vent function and execution.
And there is some serious engineering with hood vents and placement. I actually moved them forward from where I originally planned to place them. This was after extensive reading about high pressure area at the base of the windshield. It would take a multi million dollar air flow test facility to correctly find the best low pressure area for perfect placement.
It was interesting reading about Zora Arkus Dontov and cowl hoods on corvettes.
 
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superbon54

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Apr 15, 2014
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And there is some serious engineering with hood vents and placement. I actually moved them forward from where I originally planned to place them. This was after extensive reading about high pressure area at the base of the windshield. It would take a multi million dollar air flow test facility to correctly find the best low pressure area for perfect placement.
It was interesting reading about Zora Arkus Dontov and cowl hoods on corvettes.
Placement can be low buck….. or at least for close enough placement. When I break in all the mechanicals, I’m going to determine where to put the vents by running a mocked up hood with yarn strands taped all over it. Where the yarn pulls up and blows around is where the pressure is low, where it lays flat is where pressure is higher.

For those that may not understand the method to the madness, the vents go where pressure on the top side of the hood is lower to 1)”suck” the heat out of the engine bay and 2) lower underhood pressure, thus reducing up force at speed. I have an interesting book (I’m an engineer, so my definition of interesting may be different than most) regarding automotive aerodynamics and how to improve them.
 
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scoti

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This is a nice weather car. Not even close to a daily driver. The purpose of the vents is to cool engine compartment and down force. Water intrusion is not something that concerns me at all. Appreciate all the opinions and keep em' coming.

You and I have the same thoughts on hood vent function and execution.

And there is some serious engineering with hood vents and placement. I actually moved them forward from where I originally planned to place them. This was after extensive reading about high pressure area at the base of the windshield. It would take a multi million dollar air flow test facility to correctly find the best low pressure area for perfect placement.
It was interesting reading about Zora Arkus Dontov and cowl hoods on corvettes.

Placement can be low buck….. or at least for close enough placement. When I break in all the mechanicals, I’m going to determine where to put the vents by running a mocked up hood with yarn strands taped all over it. Where the yarn pulls up and blows around is where the pressure is low, where it lays flat is where pressure is higher.

For those that may not understand the method to the madness, the vents go where pressure on the top side of the hood is lower to 1)”suck” the heat out of the engine bay and 2) lower underhood pressure, thus reducing up force at speed. I have an interesting book (I’m an engineer, so my definition of interesting may be different than most) regarding automotive aerodynamics and how to improve them.
Again.... Not going against the grain; just asking questions to see what others approach to the possible issues will be since I've considered underhood venting.
Building a fair-weather cruiser is how many (most?) do it. Having built a few rides, I also know Ma Nature & her ability to change things on a nice day when you're out & about.

If I remember correctly, what works well @ one speed might yield different results @ other speeds which also dictates what would be considered 'optimal' placement? Since these aren't race cars, the placement isn't a huge deal. But if one is going through the effort, they might as well @ least try to put them as close to optimum for their needs.
 
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