Foot box vents - any opinions?

Hello gents,

When I was laying out my roadster build I originally planned on putting in some type of fresh air vents into the driver and passenger foot boxes, since I assumed they'd get very toasty during the summer months. Now that I'm in the midst of building I'm trying to decide if this still makes sense. I have a few ideas on how to pull this off, but I'd like to hear from you guys who also considered this and what you ended up doing. I'm always up for borrowing good ideas, so thanks for your input!

Rob

Thought about installing them, and lots of builders have, but in the Florida summer when it's crazy hot they would just be blowing hot air. In the cooler months I don't really need them, so just an added expense and time adder that I left out of both builds.

Most of the heat from the engine bay is eliminated with properly insulated space between footbox and the body. Once mine was sealed up, I had no issues w/ my feet feeling too hot. Most of the heat is then coming from the sun above you.
If you wanted to add vents, it's been discussed quite a bit. Some install a manual vent that they can open/close w/ a wire while others will install electric fans to blow air into the footbox. Most run the hose to the small ducts/vents on either side of the quickjacks for a fresh air source.

I went with the vented foot boxes. I took the long way around though. I did not want the incoming air that was a mere foot off the hot black road. So I made inlets in the rear wall cubby that draws air in from over the windshield and above the doors. I mounted a pair of bilge blowers in the front trunk area and ducted them down and along the space between the seats and side wall. Its a real pain in the a$$ to do but worth the effort. I have lots of pics and templates for all the ducts and plenums if your interested PM me.

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I did a no fan installation. Rebostar has a point about hot air from just a foot off the macadam. I pulled air from the top half of the vents next to the quick jacks. That helped but wasn't a 100% fix. The problem was more evident at below maybe 40mph. I had a push pull cable to a operate a valve. So, if the vents were helping I left them open, if not I closed them. I think they are worthwhile for sure.

I thought your solution was really cool; it seems like a lot of work, but it will be worth it. I'd do myself a favor by working on it because at the end of the project, when everything is ready, it might be worth it to not have done it, so it's better to add a few hours of work and do it to add a minimum of comfort!

I did footbox coolers with the fans mounted behind the seats and ducted to the footboxes. It's detailed in my build thread.

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I did the typical deal on the inside: seal up all of the openings, apply a layer of Thermotec and tape the seams, and then carpet. On the engine side of the footboxes I installed reflective heat barrier material like this. https://www.summitracing.com/parts/dei-010393

Honestly, we've never run the cooling fans even in the middle of Texas summer heat. My wife has ridden in our car in shorts and flip flops and never felt any heat. Other than it was a fun engineering exercise designing and building my cooling system we're not getting much out of them.

Thanks guys for sharing some really "cool" ideas (pun intended). I have lots to ponder here :)

Rob

I bought a package from a vendor here known as "Cobra Earl" to vent the footboxes, that I also insulated from engine heat. It uses the brake cooling vents on the front of the car with bilge fans about midway on the tubes routed from those vents to the foot boxes. At 5 years on the road and 25K miles, I can't say that they help all that much. When it's hot enough to feel like you need them, the system is sucking air into it that is approx 12" above the hot asphalt or concrete road. It's one of those "seemed like a good idea at the time" things.

I should mention that Cobra Earl passed a few years back - RIP.

I used 3/16 thick aluminum diamond plate with 5/16" spacers to create air gap , It worked very well. Ed

I have to mention that I also have the Cobra Earl powered footoboxes. As mentioned above, it's not really about heat, it's about airflow. My header is 1/4 from the footwell aluminum and when you touch the carpet inside it's not hot at all. An ditto if the walls are sealed there won't be hot air in there.

It does really help a lot at the traffic light, and it even helps with fresh air when stopped if you have a carburated engine like mine.

All that blabber said, I think we have the fans in the wrong spot if they are up top. Ideally, they should be blowing up - every now and then I get my foot at the right angle and the air going up my pant leg is just lovely.

I have had them in two builds but seldom use them as I don't notice the difference. It may be the Colorado weather. I am not doing it on my MK5 build.
Ralph

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Originally Posted by Rebostar

I went with the vented foot boxes. I took the long way around though. I did not want the incoming air that was a mere foot off the hot black road. So I made inlets in the rear wall cubby that draws air in from over the windshield and above the doors. I mounted a pair of bilge blowers in the front trunk area and ducted them down and along the space between the seats and side wall. Its a real pain in the a$$ to do but worth the effort. I have lots of pics and templates for all the ducts and plenums if your interested PM me.

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That’s a great idea! Unfortunately I already used that space in the trunk for a remote brake booster else I might have tried that.

Rob

They are definitely worth it. No, they are not going to magically blow cold air. But, moving warm air is better than still hot air.

I did the Cobra Earl kit way back with the plastic blast gates and the plastic RV effluent hoses. Stay away from both of those. The blast gates eventually jammed, and the hoses melted above the headers on a track day.

I then used metal exhaust cutouts that I got on ebay. They had motors on them, but I modified them to use the cables. I replaced the tubing with high temp tubes from Pegasus Racing. I am happy with how these work.

The bilge blower fans aren't the quietest thing. If anyone has ever found some quiet ones, I would love to hear about them.

I was going to do something like this too, but never did. I've put 1300 miles on mine this past summer and never needed them. I just insulated them well by putting Summit brand adhesive reflective insulation on the engine side and dynamat thermal insulation on the inside. No discomfort in the footbox at all.

I didn't install any vents. After 7 years of driving, I've never once had an issue with it being too warm in the footboxes, but they are well insulated with Dynomat. I also have the FFR heat/defrost, which forces some fresh air down there even when it is off. I think the fresh air coming through the hood scoop is pushed into the unit. I know many people think the heat and defrost is a waste, but my wife loves the heat on a cooler day/evening, and sometimes I drive it to work at 5am and the defroster is life saving.