Heat Entering Cockpit

[skullandbones]

I've been driving my MkIII roadster now that it is registered but the driving (app 200 miles) has been limited to short trips usually early or after dark due to the excessive heat here in PHX, AZ. They don't call it the valley of the sun for nothing. Anyway, I have triple insulated my cockpit aluminum and my wife and I spent some time tracking down other sources of heat (holes and spaces) from the engine bay. Much added insulation and then shining a flash light on the fire wall and hidden areas around the engine compartment. I think we got them all. Using a combination of silicone, weather striping, etc there isn't a place where an ant could get thru. However, on a morning cruise, we both noticed the heat infiltrating the cockpit. I think it is coming around the wind screen or over the doors or maybe over the back of the car. I've seen wind screens behind the driver on Porsches, and other roadster type cars. I was curious to know if others have observed this in your experiences with the roadster. BTW, I don't have my wind wings on yet. Planning to do that this weekend. The wind doesn't bother me as it is much like it was when I was riding a motor cycle. It's the heat that I don't like so much. It's possible that they may divert some of the heat from the side vents and around the wheels. If that is the solution, that would be good. I'm also thinking that as the weather cools off, it might actually become an asset especially on a nippy morning drive. But that's not here yet! Thanks, WEK.:cool:

[montyals]

Are your headers wrapped? Sounds like an ambient heat issue, not air flow.

[skullandbones]

Are your headers wrapped? Sounds like an ambient heat issue, not air flow.

You mean they're heat soaking the foot boxes? Please explain. They are BBK ceramic coated 4x4s. Maybe I have heat shields in my future. Thanks, WEK.

[CraigS]

Have you spent a lot of time sealing the body to the sides of the foot boxes? My most difficult area to seal had hot air coming into the cockpit seemingly through the door hinges. At the door hinge area you have a vertical 2x2 frame tube. The foot box aluminum rivets to the outer surface. Between that tube and the fiberglass body is a long gap kind of like a stretched out banana and it goes way up above the hinges to the areas where the ends of the dash are tucked in. The ends of the firewall kind of half way seal the top area but I stress the 'half way' part. Below the top of the hinge there is nothing sealing the gap. this is where I learned about the window AC unit foam. Great stuff that comes in 1.25x1.25 or 2x2 inch cross sections. It is just the right firmness that you can squeeze it down to near 1/2 inch to stick it into a gap and it will expand but not so strongly to deform anything.
http://compare.ebay.com/like/111046999194?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar
This is the brand I usually get from the hardware store but I like the 2x2 since I can always cut it smaller.

[skullandbones]

Oh yeah! We covered that in another thread too. I did not use the method you are talking about but I did seal and double seal the area. I also have done the rocker panels in expandable foam as well. After all that then Trish and I went over the entire area and inspected the possible cracks and holes (even used an inspection camera with 8mm probe. I found a 1/2 inch hole where I had put the computer braided ground to the engine block with a grommet through the firewall. It was letting hot air in like you had left the door of the house open. After all that, the 2x2 vertical post next to the driver's door hinge didn't heat up any more. and it was much more livable in the cockpit. That's why I was a little surprised when the heat showed up. I guess, by now, nothing should surprise me. So unless something has jarred lose, I think the heat is coming from the outside somewhere top, sides, or back. I will do some more checking tonight as it is easier to detect gaps with a flash light on the opposite side of the observer. Also, is wind wing install day. I am being very careful about putting them together as I think it would be real easy to break the plastic with the fasteners. Instructions say to use Loctite but be very careful not to get it on the plastic so another reason to go slow. Then I will take a test drive and see if it's any better. Thank you, WEK.

[rich grsc]

Lets see, you're driving a car with no top, no side windows and no AC. You live in Az. Not a clue as why it would be hot in your car.

[skullandbones]

Lets see, you're driving a car with no top, no side windows and no AC. You live in Az. Not a clue as why it would be hot in your car.

Very funny, Rich! Heat is all relative. So this is above and beyond what is normally expected. When Trish and I were having that conversation it was about 9:30 PM and we had just left the Sonic to head home. So it was pretty nice outside. There was still a lot of unexplained heat swirling around the cockpit. When I am driving along at noon in July, I just grin and bare it knowing that I am the idiot driving a Cobra in AZ during the summer! Thanks, WEK.

[mikiec]

There are a bunch of us idiots out here driving in the summer. I have been driving 2290 out here, PHX, for the past 13 years. You get used to it. I've had the roadster out in over 115 days. It's a little warm. Just drink plenty of water, wear sunscreen. One trick. wear a floppy hat that you can soak with water if needed. Mostly the AZ gang use the summer to do their projects on the car. Kinda like our northern brethern do with winter projects.

Mike

[DaleG]

When you say "triple insulated", what do you mean? Is the cockpit insulated on the engine-side with something like Thermotec aluminized heat blanket? Area between body and firewall? Is hot air coming in down by the doors in the footbox area...i.e. do you feel a draft while driving if you put your hand down by the door hinge?

[CraigS]

Do you have Earls fresh footbox air kit? It helps some. I got the inlet pieces w/ two openings but only one actually cut open. I was looking at this last week as I am surprised how hot the incoming air is and noticed that my driver side has the hose connected to the bottom inlet. One project this week is to flip it over so I get air in at the top of the duct. The further from the black macadam the better. I have also wraped the hose where it passes above the headers w/ some HD fiberglass that has foil on one side.

[skullandbones]

When you say "triple insulated", what do you mean? Is the cockpit insulated on the engine-side with something like Thermotec aluminized heat blanket? Area between body and firewall? Is hot air coming in down by the doors in the footbox area...i.e. do you feel a draft while driving if you put your hand down by the door hinge?

Dale, I tried something a little different. I used the Hushmat (Dynamat like product) inside of alum panels first. Then a layer of green pad for dampening sound on wood laminate (glued down). Then a layer of 1/2 inch premium carpet mat. It was a lot to stuff in the cockpit but there actually was room for it. It gives very good padding and sound dampening. There may still be some heat soak thru the aluminum. I don't know yet. I still need to get a point and shoot thermometer to check that out. One thing I was considering but have not tried is some header heat shields. A couple of guys have done them and after looking at aluminum's special properties, I tend to agree that they would be helpful for heat soak. My huge aluminum intake is a perfect example of a giant heat sink. However, I still think I'm getting heat from around the wind screen just above the door. I wish I could see the roadster in a wind tunnel and smoke gun. I will bet there is a vortex right there at that lower wind screen area. So the next thing is to drive it with the new wind wings which I attached last night. They look nice. Hope they make a difference. Thanks.

Note: Did take care of the areas on both sides outside the footboxes and under the rocker panels. I don't think I have any heat sneaking thru there. I feel like a test pilot every time I get into the roadster. Hey Chuck why don't you get into this rocket with a seat and see how fast you can go!!! We call it the X plane. Sure, why not.


Do you have Earls fresh footbox air kit? It helps some. I got the inlet pieces w/ two openings but only one actually cut open. I was looking at this last week as I am surprised how hot the incoming air is and noticed that my driver side has the hose connected to the bottom inlet. One project this week is to flip it over so I get air in at the top of the duct. The further from the black macadam the better. I have also wraped the hose where it passes above the headers w/ some HD fiberglass that has foil on one side.

No, I sure don't have those. I believe you have tried every gadget you can put on one of these cars. Just kidding. I actually have looked at them and will consider a retrofit. I've only heard good things about having a little fresh air in the foot box. Trouble is, I have a highly modified driver foot box. It's an MKIII but looks a lot like an MKIV with clutch quadrant on left side (Forte). Had to custom finish the top and outside of driver foot box so there are not too many flat surfaces to mount one of those inlets. I may have to fab an inlet and mount the mechanism remotely. But still a good idea.

Well: off to the races. I will try the new wind wings and see if there is any difference in the comfort level. Thank you, WEK.

[skullandbones]

Took the roadster out this morning for the first time with the new wind wings. Got over 200 miles on it now. I had a pleasant surprise. It felt a little cooler when everything came up to temp. I had a video but it was too boring to show. Went the 35 mph road out to AJ. Next time I will go the faster route and take the free way for a while. Also, I will have to do an evening drive to see if it is better than last time we did it. Thanks, WEK.

[CHOTIS BILL]

You can always use the poor mans wind tunnel, pieces of yarn tapped to the body and then force yourself to take a drive and see which way the wind blows. I have also made good use of spraying a light film of WD-40 before a drive and check the flow pattern afterwards.

Bill Lomenick

[skullandbones]

I should have thought of that first!

http://www.apsltd.com/c-4717-telltalessail.aspx

Being a sail maker and sailboat racer, I've stared at those things for hours on end. We used to put rows of them on a sail to give more sensitive reading so you could tell even when the wind layer was starting to delaminate from the sail surface before it let go (stalling). If it ever comes to that, those and a GoPro camera mounted strategically would do a pretty good job. Thanks for the idea. Pretty cool! WEK.

[WIS89]

WEK-

I used to use cassette tape for my telltales, and they worked great. I think it's a fantastic idea. You could literally put them all over the side of the car with the GoPro camera recording each side at a time. Of course, you will want to be able to coordinate the data with your speed and if at all possible any indicators giving true wind, and not just relative wind. However, even if true wind and vehicle speed is unavailable, there will be a great deal of data to collect that should help you! Be sure to play with the wind wings as well, to see their potential impact. It's a perfect solution to help you decide where any potential trouble spots would be. The good thing is that you should never end up luffing!! ;-o)

Good luck, and go crazy with cassette tape, and let us know how things turn out!

Regards,

Steve

[skullandbones]

Another opportunity to inject sailing terminology into the conversation! Luffing: not usually a term common in the FFR or Cobra forums.

But it is a possibility to answer some questions about the air circulation and especially turbulence and low pressure areas around the car. I may use this technique to see if a splitter works that I am thinking about.

Back to the subject: I am going to reserve judgment on how much the wind wings help divert the heat from the vents and other forward areas 'til I have taken a couple of night drives. I also have a laser temp device that I just got so I will do some shots into the foot boxes to see if there is some heat soak going on. Man that little engine sure puts out a lot of heat. My Holley aluminum manifold is hot as hell after a drive even with the phenolic 1 inch spacer. I hope the aluminum panels aren't transferring that much heat. To be continued. Thanks, WEK.

[montyals]

I'd try wrapping the headers up until they connect to the straight pipes (if you still have access via the engine bay). I double layered my EZ Cool insulation throughout the entire cockpit even though the manufacturer said one layer was enough. In some area (like the driver footbox) it's triple layered. In a few days I'll be wrapping my BBK headers to 1) reduce the engine bay heat and for what it's worth 2) further reduce footbox heat, even if it's only by one more degree. Every little bit counts. Good luck with what ever you decide!

[Mark Reynolds]

Install some Zero Clearance on the engine compartment side of your foot boxes - particularly the front and the side facing the headers.

http://www.breezeautomotive.com/details.php?prod_id=773

[DaleG]

Side vents and sun screens do help divert air from the cockpit. I'll post a pic of my Thermo-tec blanket on the engine bay side of the cockpit when I get home later this week. Duplicating what I did on the MK II (along with D'mat inside and Earl's vents) and never had a heat issue in the cockpit, either in nor-Cal or in Arizona (Prescott, and drives to the valley). Also used one of our vendors "swim noodle" insulation between body and footboxes; not a wisp of air coming in behind the doors.