Author Topic: Cockpit ventilation - how much is needed/recommended?  (Read 6605 times)

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Offline SteveM

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Cockpit ventilation - how much is needed/recommended?
« on: August 07, 2013, 04:21:08 PM »
I am building a Dodge Rampage, and getting fairly close to having it ready to run at World of Speed.  My question of the day is in regards to cockpit ventilation.

I have fixed position lexan side windows, which I have tried to make fit as close to OEM as possible.  (there is still a small gap at the rear of the window).

I am using the OEM laminated front windshield.  Lexan back window.

I just bought a small lexan NACA duct, with 1-1/8" hose size, which I intended to mount into the driver's side window.  Is this enough, should I also cut a hole in the passenger's side rear window?

Am I better off cutting 3" or so holes in both side windows?

As always, any advice is appreciated.
1/2 of the Rampage Brothers

gkabbt

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #1 on: August 07, 2013, 05:19:44 PM »
Steve,
I think you will be OK with only one.....in the drivers side window.
With many on their way to Bonneville, you might not get answers quickly.

Having said that, this is what Chris did with the Midget:

It appears that on the right car, you can completely replace all of your windows with Lexan for less than $150.00.

Key to that, of course, is having windows that are essentially flat.

When I overlaid my firewall, I covered all the original cockpit venting with .060 steel, which meant I had no “forward pointing fresh air intake or breathing system directed to the driver”  (3.E).  I bought a Butler NACA duct, thinking I’d install it in the driver’s window -

 

Photo courtesy of the Butlerbuilt website.

The problem wound up being that in the window, it sat so far back that it would interfere with the net.  The vent window, on the other hand, sat up in the sweet spot, just in front of where the net will fall.  This is where my skills as a former hobby shop clerk and 1/25 scale model hacker came into play –

I cut the bung and flange so it would fit over a hole I drilled through the window –
 


And then I trimmed up the rest of the duct and created a “forward pointing fresh air intake” -



A little duct tape (imagine that – using duct tape for a duct), a few pop rivets and BINGO.


Hope this helps,
Gregg

gkabbt

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #2 on: August 07, 2013, 05:37:51 PM »
Just looked at the rule book and it says that along with the forward facing fresh air intake you need to have adequate venting to carry away fumes.

Here are a couple of pics of Andre Moreau's Stude with a NACA duct on both sides and he has run at Bonneville several times.....probably there now.
I'm assuming  :?  the one on the passenger side is for venting.





Hope this helps,
Gregg

Offline hotrod

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #3 on: August 07, 2013, 05:55:40 PM »
Another issue to consider is will the intake you plan on adding pull in flames and smoke if you have a full on engine fire?

Some car builders have fashioned air intakes that come from the very front of the car to the drivers area, using a fire proof path like a seamless metal tube to keep the drivers compartment at positive pressure at speed. This would not only help vent fumes but work against fire burning through the fire wall in any small gaps. It would also pickup fresh air that is not likely to be smokey or hot in case of a significant fire or engine blow up.




gkabbt

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #4 on: August 07, 2013, 06:02:09 PM »
Very good point Larry (hotrod) and I have seen that on several cars in the past.

Gregg
« Last Edit: August 07, 2013, 06:25:29 PM by gkabbt »

gkabbt

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #5 on: August 07, 2013, 06:24:48 PM »
Steve,
Could you put a tube like Larry (hotrod) suggested along the frame rail? 
If there is enough room you could get from the front end to the drivers compartment.
You could then use the NACA duct you have in the back window for venting.



Gregg


Offline Tman

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #6 on: August 07, 2013, 07:12:17 PM »
Steve,
Could you put a tube like Larry (hotrod) suggested along the frame rail? 
If there is enough room you could get from the front end to the drivers compartment.
You could then use the NACA duct you have in the back window for venting.



Gregg



That is what I would look for!

Offline SteveM

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #7 on: August 07, 2013, 07:29:58 PM »
Thanks, guys.  I will scope it out this evening.  Maybe some 1" EMT?


Steve.
1/2 of the Rampage Brothers

Offline Tman

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #8 on: August 07, 2013, 11:17:28 PM »
Yes Steve, I have seen it done with 1" tubing

Offline SteveM

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Re: Cockpit ventilation - how much is needed/recommended?
« Reply #9 on: August 08, 2013, 01:28:27 PM »
After scoping it out last night, I think I'm going to make it up with 1" square tubing.  I don't have a good way to bend 1" round, and the 1" square can be cut and welded pretty readily. 

I'll put this on my list of weekend projects (not too many weekends left).

Steve.
1/2 of the Rampage Brothers