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Thread: Airflow over the car and interior cooling.

  1. #1
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    Airflow over the car and interior cooling.

    As you all know the inside temperature inside the Coupe can reach pretty high values. Unfortunately mine is not equiped with aircon
    However last year during a hot day I discovered that there is a pretty hot airflow over the roof and along the side windows. This can only be caused by the hot air coming from the radiator. When you stick your had out it's very easy to notice. About 4 inch above the roof or out of the window the air is much cooler.

    So my question is has anyone did some investigations about how to control this ? It would make a big difference if cool air would flow into the interiour instead of hot radiator air.

  2. #2
    Senior Member SingleMaltWSKY's Avatar
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    I'm not really sure that there's much you can do about this issue. The rad is designed in a way that exchanges heat directly out into that big hole in the hood - apart from deflecting the air with some sort of damn to the sides OR, a major reconstruction having the air directed to the ground (eliminating the hood opening, reposition of the rad and sheetmetal to direct air downwards).....I don't see how you could.
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  3. #3
    Steve >> aka: GoDadGo GoDadGo's Avatar
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    Wow, That's An Interesting Issue!

    Could you possibly add louvers or maybe decoratively dimple die the aluminum panel so that air could then be drawn from the engine bay as well as the radiator?

    Could that help?

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    Member Gbeck's Avatar
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    This isn't very helpful, but your post reminded me that cabin heat was a problem in the original Daytonas from the start. During the 1964 12 Hours of Sebring they resorted to cutting a vent in the roof to help cool the drivers. CSX-2287 now has a vent cut into the rear spoiler to help with ventilation.
    This link about driver Dave Macdonald shows the story of the Sebring race in pictures, including a shot of Phil Remington cutting the roof vent. http://www.davemacdonald.net/gallery...bring12hrs.htm
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    The notion of putting a partition between radiator and engine bay and directing warmed air from the radiator out the top of the car gained popularity for a while. The original prototype of the Jaguar XJ-S had the same feature, but it was dropped before the car went into production in 1975. The idea is to lower the temp in the engine compartment, which is good for the life of nonmetallic components like belts and hoses.

    The '65 Coupe also has openings on the side which allow air out of the engine compartment, and it's probably pretty warm due to the engine and exhaust piping being in there. The end result is that the passenger compartment is pretty well surrounded by warm air.

    Doing anything about it without adversely impacting the outward appearance of the car would be challenging. The first idea that comes to mind would be to install ducts that collect cool air from the front of the car and direct it into the passenger compartment. There are aluminum panels on either side of the chamber just forward of the radiator; holes could be cut in these panels and ducts connected and routed through the engine compartment to the firewall. It'd be necessary to insulate them, and they'd look awful under the hood, but they should make life more tolerable in warm weather.

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    Senior Member AC Bill's Avatar
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    Originals also had a scoop on the hood to direct air flow into the drivers foot box, as well as scoops at the rear of the door windows. No clue how effective they may be, but it must have helped somewhat, to sacrifice aerodynamic's.




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    Any heat exchanging system needs flow in and flow out - fin fans in the chemical industry are based off this cinception - and there are numerous ways on how to control.

    Something as simple as 1/4 inch high by 4 inch wide intake scoop on the roof with appropriately sized side exits near the back hatch would do wonders to reduce cabin temps with minimal affect on CdA. A little bit of continuous air flow has a HUGE impact on cooling/heat removal

    The math used here is pretty simple - is an “X” increase in CdA worth 15-20 degrees F cooler in the cockpit?

    I would say yes......

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    See, I worry a little about those scoops because they're not far enough to either side. At 150 mph they might work OK, but at 40 mph I'd expect the hot air coming out of the radiator outlet might flow right into those inlets. In fact, in the upper photo it looks as though the scoop has been located all the way over onto the fender, which would probably work fine -- if you can accept the appearance.

    They're also going to route any rain directly onto your feet, are they not? Or is it sacrilege to suggest our cars would ever be driven in the rain?

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    I happen to know that the Ferrari 250 GTO - the Daytona Coupe's competitor and a very similar layout -- had a series of 9 holes, a little over an inch in diameter, across the rear windshield. Whether these were to help ventilate the driver or reduce lift, I dunno, but they probably did a little of both.

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    If anybody has the skills, NACA ducts might be a better idea than scoops. They'd do less to the lines of the car, anyway.

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    Thanks for all the comment.

    This last week I ran some tests with carboard pieces. It's became 100% clear that the hot air is coming from the radiator through the hole in the bonnet. When I closed it only cool outside air flows over the roof and along the side.

    Before I will explain what I modified I have to tell that my FFR Coupe has a different chassis. Which is the result of our Dutch law which makes it's next to impossible to use the original FFR chassis. So my chassis is from an (believe it or not) English sportscar (like the orginal but not a Cobra). This means the radiator is positioned in a rather strange way. One of the pictures will show this. The cooling is still very effective. This doesn't change the way the hot air flows outoff the bonnet.

    Before I started building about 6 years ago I already knew inside temperature would be a problem. So I already made pretty effective airvents. The small scoops are connected to 2 vents on the dash. These work very well. Secondly the big scoop in the bonnet feeds the interior heater which is also quite powerfull. The scoops in the rear are connected to a hugh tube which cools the INSIDE brakediscs. The differential is from an '80 Jaguar XJ These scoops are also catching air for 2 adjustable ventilation holes.

    airvent-1.jpg

    Airvent-2.jpg

    Finally I've made a mechanisme so I can put the rear window about 2,5 inch open.

    Rear window.jpg

    However to avoid that the hot radiator air is flowing outoff the bonnet I basicly closed the hole in the bonnet. This part can be taken out very easily by removing 4 screws.

    WP_20180513_14_59_44_Pro.jpg

    I made a hole on both left and right side of the radiator housing. So now hot radiator air flows into the wheel wells.

    radiator air out-2.jpg

    radiator air out.jpg

    Next week tempertures will go over 25 degrees Celsius = 77 in your terms Which is about the level when it starts to get pretty warm inside.
    Last edited by Daytona11; 05-14-2018 at 12:26 AM.

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    Steve >> aka: GoDadGo GoDadGo's Avatar
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    Good Stuff & An Interesting Solution!

    Also, what you had to do to build your dream car in spite of "Government Red Tape" is inspiring.

    We've got goofy laws over here as well which vary state by state.

  13. #13
    Senior Member John Dol's Avatar
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    Goed gedaan!
    Nice car, let us know how you make out.

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    Senior Member CraigS's Avatar
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    I don't understand the last picture. It's a nice piece of aluminum labeled air outlet. How is that?
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

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    Quote Originally Posted by CraigS View Post
    I don't understand the last picture. It's a nice piece of aluminum labeled air outlet. How is that?
    There are now 2 square shaped holes on both sides of the radiator box where the hot air from the radiator is flowing out into the wheel wells instead of through the hole in the bonnet.
    Last edited by Daytona11; 05-14-2018 at 12:28 AM.

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    Any concerns with the hot air from radiator now venting in wheel wells in terms of increased brake temperature?

    I would love to ride in 25 deg C weather......was close to 38 deg C on F1 track here this weekend and can get absolutely scorching in summer time....hence most events here are at night - but it can still be well above 40 C for hours after sunset.......

  17. #17
    Member Gbeck's Avatar
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    I just saw a You Tube video where Peter Brock describes his personal Daytona Cobra Coupe. He mentions that he added two rectangular slots above and just behind the windshield to extract warm air from the cockpit. Search for “Peter Brock’s World” on You Tube.
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  18. #18
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    Found it!

    https://www.youtube.com/watch?v=-cbVWSUbvu8&index=4&list=PLEGgS3yBiCot-XUINqzlYn74C6DUcaaAZ[/URL]

    From about 40 sec. he starts talking about it.

    Could be an interesting option.

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    The roof vents combined with a way to pull cooler air in down low - from say side just in front of door - would create enough flow to provide a fair amount of cooling - just sucking in from windows won’t get the heat build up around fire wall out....

    Definitely something to try

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    Quote Originally Posted by gnd_hog View Post
    Any concerns with the hot air from radiator now venting in wheel wells in terms of increased brake temperature?

    I would love to ride in 25 deg C weather......was close to 38 deg C on F1 track here this weekend and can get absolutely scorching in summer time....hence most events here are at night - but it can still be well above 40 C for hours after sunset.......
    I don't have any concerns about the brakes. The hot air seems to flow over the tires. So it maybe wamm up the tires a little. That will make them only stickier I don't do racetracks or something like that. However I do mountain roads in the European Alps (especially the Italian). So that means some heavy braking going down. Speeds are not low. But because the engine is big this also gives a significant part of the total braking force.

    2 year ago tempertures went up to 35-40 degrees Celsius (95-104 F). I think it became around 60 (140 F) inside. I never felt so bad as that time.

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    Quote Originally Posted by gnd_hog View Post
    The roof vents combined with a way to pull cooler air in down low - from say side just in front of door - would create enough flow to provide a fair amount of cooling - just sucking in from windows won’t get the heat build up around fire wall out....

    Definitely something to try
    Roof vents have 1 important downside. When it rains the water will come easily inside. Maybe not while driving but when the car is parked for what ever reason.

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    Depends on use of car i guess about the rain entry point - my car won’t have any side windows so not really too concerned....

    Cooler place to sit during a 45 minute race much more critical - IMO.

    As far as the inside temp approaching 60 deg C - that’s the normal temp in direct sunlight here...

    Going to try the roof vents similar to video and figure out some way to get air flow into the pedal box area as low and as close to firewall as possible - think will have significant impact.....

  23. #23
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    Just put in some AC! I run a LS2 with a 6 speed in mine its fabulous. Getting 26 MPG doing 80-100 in 6th. LS weighs about 100 lbs(!) less than a Coyote, costs half as much and makes 408 HP 410 Torque at the tire. Half the size too!

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