interesting thread 
op:
op:
boxing in the radiator
- Thread starter Fast99Snake
- Start date
Does anyone have pics of what they used to attach the material used for boxing?
I was cruising another great thread on CC and came across this article again and thought I should share it with you guys since CC is often so hostile to newbs.
I feel that this is a terrific article that explains very well WHY what works WORKS!
Written for Z cars(Datsun/Nissan), but the physics apply to every car.
LINK_> Aerodynamics & Cooling
Let me toss out some of my qualifications first, not to come across as a bragger but just to say that I have some experience in this area
(1.Aero. Eng. degree at VPI, 2.Design Engineer at Fairchild, 3.USAF Research Pilot at Wright-Patterson AFB & Edwards AFB etc., 4.Now flying big fat jet through air).
This subject takes a lot of words to explain but here goes.
First, throw away the term laminar flow.You can pretty well bet that due to our close proximity to the ground and the existence of turn signal lenses, bumpers, bugs, wipers, molding, etc that our Zcars are operating well into the turbulent air flow regime.You don't really care. In fact many aircraft manufacturers purposely use vortex generators to create turbulent flow on their high flying jets.
As air approaches your car, air particles are affected in different ways depending on their relationship to the body of the car.These air particles slow down and build up upon each other, each one trying to find the easiest way around your car.The ones about four feet above the ground simply do a little jog and divert over the top of the windshield and accelerate along the roof and down along the hatch.Air particles about two feet above the ground slow down slightly as they approach the front of the hood, then accelerate over the hood, slow down again at the windshield wipers, and accelerate again as they pass over the windshield and roof.
Air particles about one foot off the ground are really slowed down and will either try to go up and over, down and under, around, or through the radiator or any other convenient hole in the nose. By the way, this very slow area of air is called the stagnation point. Stagnation points are great places to put radiators. Now, air particles near the ground will slow down slightly then accelerate under the car before twisting and turning due to the complicated affects of the under carriage.
This is how the slowing and accelerating of these air particles applies forces to the car:Simply put, air that is slowed down builds up high pressures, while air that is accelerated lowers pressures.High pressures on the car start at about the front suspension cross member, and run forward to the front bumper on up and over to a point about one foot aft of the front edge of the hood.From this point back to about 6 inches prior to the wipers, low pressure exists.From that point to about half way up the windshield, another high pressure area forms.From the middle of the windshield on up over the roof, a low pressure area exists. Various aerodynamic books as well as fundamentals of flight books show drawings of this pressure gradient on wings.The Z is just a complicated wing.
I think the question was, "how do we use the aerodynamics of the car to increase engine cooling" or something like that. Nissan already attempted this in the 280 with hood louvers. Notice that the location of these louvers are as aft as possible on the hood but prior to the high pressure area near the wipers.This places them in a low pressure area, allowing the hot air in the engine compartment to vacate.This also allows the air stagnating on the nose to more easily pass through the radiator.
It's been mentioned that some models had a piece of metal starting from the aft edge of the radiator, running aft to the cross member. I am not familiar with this since I only have a 240Z but I have seen similar devices on Mazda's and other hot running cars.These devices were installed to smooth and accelerate the air under the radiator and combined with tiny louvers, extract air out of the engine compartment, much as the 280Z louvers did on top.This only worked while the vehicle was in motion, the faster the better.Contrary to what some might think, this piece of metal does not improve cooling while the car is stationary and in fact, if the cooling fan is not well shrouded, this piece of metal can hurt air flow through the radiator while the car is stationary. This metal panel's effectiveness is further neutralized with the installation of an air dam or spoiler.An air dam will do just that, prevent air from going under the car and therefore not flowing along the surface of the louvered panel.
An air dam has other great benefits, however. First, it prevents air from compressing under the nose of the car which stops that previously mentioned high pressure area that results in front end lifting and lower grip. Second, it also prevents air from interfering with the undercarriage which causes drag.Third, it funnels air into the radiator improving cooling. This funneled air can also be used to cool oil , brakes, and even be fed into the intake system on some cars.Of course air dams only work when the car is moving.
What advice would I give to the gentleman trying to cool the V-8? 1)Get a good radiator.I use a huge Griffin radiator. Works great, is light, looks cool, ain't cheap though. 2) Use a 280 Z hood.If you want to modify a hood with louvers, run the louvers from no forward of the front axles back to about where the 280Z louvers are. 3) Properly shroud the cooling fan so that every last molecule of air that passes through the radiator also passes neatly through the fan.This is the secret for cool stop and go performance. 4)If you won't be using an air dam, a belly pan with louvers running from the radiator to the cross member would help at speed.5)If you want to use an air dam(my recommendation), don't use a belly pan. 4)Make sure that any path the air could take to bypass the radiator is sealed. Air should be used to cool stuff or feed the pistons, not just aimlessly wandering around frame members.
About NACA ducts.They are not used to evacuate air from enclosed compartments.They are only used to take air flowing with good velocity along a surface and remove some for useful purposes.They can not take slow air from an engine bay and remove it out into the free stream.If you want to do that you have to use louvers.On some aircraft they are refereed to as cowl flaps.Look at the old pictures of the SUNOCO CanAm turbo car to see how they used louvers to suck air out of the top of the wheel wells. This is big time over kill, however.The real secret is a good radiator and a good fan.
Let's not under estimate amount of heat increased airflow can remove!!
I feel that this is a terrific article that explains very well WHY what works WORKS!
Written for Z cars(Datsun/Nissan), but the physics apply to every car.
LINK_> Aerodynamics & Cooling
Let me toss out some of my qualifications first, not to come across as a bragger but just to say that I have some experience in this area
(1.Aero. Eng. degree at VPI, 2.Design Engineer at Fairchild, 3.USAF Research Pilot at Wright-Patterson AFB & Edwards AFB etc., 4.Now flying big fat jet through air).
This subject takes a lot of words to explain but here goes.
First, throw away the term laminar flow.You can pretty well bet that due to our close proximity to the ground and the existence of turn signal lenses, bumpers, bugs, wipers, molding, etc that our Zcars are operating well into the turbulent air flow regime.You don't really care. In fact many aircraft manufacturers purposely use vortex generators to create turbulent flow on their high flying jets.
As air approaches your car, air particles are affected in different ways depending on their relationship to the body of the car.These air particles slow down and build up upon each other, each one trying to find the easiest way around your car.The ones about four feet above the ground simply do a little jog and divert over the top of the windshield and accelerate along the roof and down along the hatch.Air particles about two feet above the ground slow down slightly as they approach the front of the hood, then accelerate over the hood, slow down again at the windshield wipers, and accelerate again as they pass over the windshield and roof.
Air particles about one foot off the ground are really slowed down and will either try to go up and over, down and under, around, or through the radiator or any other convenient hole in the nose. By the way, this very slow area of air is called the stagnation point. Stagnation points are great places to put radiators. Now, air particles near the ground will slow down slightly then accelerate under the car before twisting and turning due to the complicated affects of the under carriage.
This is how the slowing and accelerating of these air particles applies forces to the car:Simply put, air that is slowed down builds up high pressures, while air that is accelerated lowers pressures.High pressures on the car start at about the front suspension cross member, and run forward to the front bumper on up and over to a point about one foot aft of the front edge of the hood.From this point back to about 6 inches prior to the wipers, low pressure exists.From that point to about half way up the windshield, another high pressure area forms.From the middle of the windshield on up over the roof, a low pressure area exists. Various aerodynamic books as well as fundamentals of flight books show drawings of this pressure gradient on wings.The Z is just a complicated wing.
I think the question was, "how do we use the aerodynamics of the car to increase engine cooling" or something like that. Nissan already attempted this in the 280 with hood louvers. Notice that the location of these louvers are as aft as possible on the hood but prior to the high pressure area near the wipers.This places them in a low pressure area, allowing the hot air in the engine compartment to vacate.This also allows the air stagnating on the nose to more easily pass through the radiator.
It's been mentioned that some models had a piece of metal starting from the aft edge of the radiator, running aft to the cross member. I am not familiar with this since I only have a 240Z but I have seen similar devices on Mazda's and other hot running cars.These devices were installed to smooth and accelerate the air under the radiator and combined with tiny louvers, extract air out of the engine compartment, much as the 280Z louvers did on top.This only worked while the vehicle was in motion, the faster the better.Contrary to what some might think, this piece of metal does not improve cooling while the car is stationary and in fact, if the cooling fan is not well shrouded, this piece of metal can hurt air flow through the radiator while the car is stationary. This metal panel's effectiveness is further neutralized with the installation of an air dam or spoiler.An air dam will do just that, prevent air from going under the car and therefore not flowing along the surface of the louvered panel.
An air dam has other great benefits, however. First, it prevents air from compressing under the nose of the car which stops that previously mentioned high pressure area that results in front end lifting and lower grip. Second, it also prevents air from interfering with the undercarriage which causes drag.Third, it funnels air into the radiator improving cooling. This funneled air can also be used to cool oil , brakes, and even be fed into the intake system on some cars.Of course air dams only work when the car is moving.
What advice would I give to the gentleman trying to cool the V-8? 1)Get a good radiator.I use a huge Griffin radiator. Works great, is light, looks cool, ain't cheap though. 2) Use a 280 Z hood.If you want to modify a hood with louvers, run the louvers from no forward of the front axles back to about where the 280Z louvers are. 3) Properly shroud the cooling fan so that every last molecule of air that passes through the radiator also passes neatly through the fan.This is the secret for cool stop and go performance. 4)If you won't be using an air dam, a belly pan with louvers running from the radiator to the cross member would help at speed.5)If you want to use an air dam(my recommendation), don't use a belly pan. 4)Make sure that any path the air could take to bypass the radiator is sealed. Air should be used to cool stuff or feed the pistons, not just aimlessly wandering around frame members.
About NACA ducts.They are not used to evacuate air from enclosed compartments.They are only used to take air flowing with good velocity along a surface and remove some for useful purposes.They can not take slow air from an engine bay and remove it out into the free stream.If you want to do that you have to use louvers.On some aircraft they are refereed to as cowl flaps.Look at the old pictures of the SUNOCO CanAm turbo car to see how they used louvers to suck air out of the top of the wheel wells. This is big time over kill, however.The real secret is a good radiator and a good fan.
Let's not under estimate amount of heat increased airflow can remove!!
Great post Jimmy! Is there any evidence that while moving a significant low pressure area is created over the stock hood vents? If so, (without altering the OEM hoodvents) could there be some sort of boxed ducting attached to the underside of the hood where the vents are and ran more towards the middle of the hood thus pulling more of the hot stagnant air out from above the engine instead of in front of it. If there was enough vacuum then it would only take a very low profile amount of ducting to work. This would also help with velocity. I can try to draw something up in autocad if what I am asking is not clear. Figuring out a way to attach it would be another question all together.
-Jeff
-Jeff
Not a new concept. Find pictures of the 66 Cobra Daytona or Corvette Grand Sport. note a small lip at the leading edge of the vent helps speed the air over the vent.
Question about the air dam. On a lowered car, does it have to still be 4" or so deep? I plan on putting a dam on this week and running it to the middle of the wheels, but I was only going to go about a 1/2 inch taller or so than the stock one.
The lower and wider it is the better it will perform. If it is too low it will wear away eventually.
Where are you getting your materials from? I'm interested in doing the same thing.
Home depot. Just the plastic garden dividers that you use to separate planters from grass
Anything larger than stock is still an improvement.
Make it too big to begin with and drive around and see if you can live with it.
If the scraping drives you insane trim it in small increments until you get it where it is as big as you can tolerate.
Big as in "tall" or length? You've mentioned taking it to the middle of the tires as far as width is concerned, correct?
When i was running one it extended all the way the outside edge of the bumper cover. There is a small lip to attach it too. I many driveways later it had worn away so it didn't scrape anymore except the really steep driveway. I did buy it from either lowe's or home depot. Make sure you get the thick one, the thinner kind just bends too easy at speed.
Both it will trim itself from scraping.
THIS:
I would go all the way wide and just let it wear down on it's own, like Carlos mentions above.
What do you think? I might got taller for an actual track day, but I figured for a street car this was a good start
I used three pieces and overlapped the two sides over the front one about 1/2 inch. It should create the high pressure area the same. It is completely removable in about 5 minutes and I can easily change height if I need to. I might make a couple more mock ups with different heights and see what happens with temps, but I need to box the radiator in first.
I used three pieces and overlapped the two sides over the front one about 1/2 inch. It should create the high pressure area the same. It is completely removable in about 5 minutes and I can easily change height if I need to. I might make a couple more mock ups with different heights and see what happens with temps, but I need to box the radiator in first.
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There will eventually be a plate blocking the bottom of the HE and radiator.
I was under the impression that this created a high pressure area UNDER the car making the air search for another way. When the radiator is boxed in, that leaves the ONE low pressure spot, the radiator, on the bumper and the air doesn't try and escape/rout under the car.
My understanding, but I am still learning too :beer:
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Haha Hey I don't know either that's why I commented. I will be removing my bumper probably this week to mock up the shapes I'll need to box in the radiator, h/e and make the dame. I'm hoping doing this will lower my temps enough to be able to go out and play on the track without overheating. I'm not a serious track guy like some of these other guys, I just want to have alittle fun wih me and he wife at VIR
Anywhere you put the dam will cause a low pressure area behind. Run your hand through water, watch where it tries to fill in behind. You don't really want the dam UNDER the car angled up as this will trap air UNDER the front of the car were you want lift the least in newer Mustangs. With the old Fox , it was a bottom feeder. There was a hole..actually 2 of them, in the bumper cover and an air dam below the radiator suoort, so it created a low pressure behind the radiator support, and directed the air up to the radiator.
Note the idea placement would be at the front edge of the bumper and just seal back to the radiator, but because of parking curbs, that doesn't work so good on the street. It really works on track, as I have managed to pull 2 such plates down and off under the front of my SPU car.
Note the idea placement would be at the front edge of the bumper and just seal back to the radiator, but because of parking curbs, that doesn't work so good on the street. It really works on track, as I have managed to pull 2 such plates down and off under the front of my SPU car.
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