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Firewall foreward cooling air needs

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recapen(at)earthlink.net
Guest

Posted: Mon Feb 25, 2008 6:01 am Post subject: Firewall foreward cooling air needs

Here's the setup:



IO360B1F6 with CS MT prop, AFP injection, LASAR ignition, Vetterman crossover heater/mufflers in a SamJames cowled/plenum'd RV6A.



I'm planning on putting the oil cooler behind the #4 cylinder with its cutout for airflow feeding the oil cooler.



My heater/mufflers require cooling air over them even when they're not heating the cockpit according to Larry.



I'm thinking that taking the cooling air for both heater/mufflers from the back plate behind the #2 cylinder should be OK - since I'm taking a chunk from each side.



Is this a valid thought? - or does it not matter since I have a plenum.

For the cabin heat air, would it be better to take the air from the vertical plate or the 40 degree angled plate below it?



Thanks,

Ralph

aurbo(at)ak.net
Guest

Posted: Mon Feb 25, 2008 6:48 am Post subject: Firewall foreward cooling air needs

Ralph,



I did not know that the heat muffs required cooling air flowing over 

(through?) them at all times. Why is that?



I just installed my carb heat yesterday and I used another one of Van's heat 

muffs instead of the standard issue carb heat gizmo. I elected to get the 

carb heat air from inside the cowl instead of cutting another hole for it in 

the air inlet ramp. That is the way Cessna and the standard Van's carb heat 

muff does it and it seems to work just fine.



For the air supply to the heat muff for cabin air I went even lower and took 

the air from the plate right next to the cylinder fins. I and others have 

thought this is a good place because the air will be pre-warmed as much as 

possible.



How do you like that Sam James cowl?



I had a tough time getting my Van's standard issue cowl to fit.



Mike Ice

RV-9

firewall forward

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recapen(at)earthlink.net
Guest

Posted: Mon Feb 25, 2008 7:23 am Post subject: Firewall foreward cooling air needs

Mike,



The way I understand it is in order to get a decent heat exchange, the heater box metal is slightly thinner - coupled with the fact that it is a muffler internally means that it will get pretty hot.  This also eliminates using preheated air as an option.



I really like the Sam James cowl.  I am still installing the plenum - it's not fitting nearly as well as the cowl.....too wide in the front, too short in the back.  I started with Vans baffle kit - but that doesn't account for the variances - I was able to adapt the inlet ramps to the plenum intakes though....but it took a bunch of work.



Ralph



--

aurbo(at)ak.net
Guest

Posted: Mon Feb 25, 2008 8:23 pm Post subject: Firewall foreward cooling air needs

Ralph,



Hmm! Perhaps I am not quite understanding this but don't you want the heat 

muffs to be hot. From what I have heard getting any heat into an RV (I don't 

know what your building) is hard enough to do.



I am glad you like your decision with the James cowl and plenum. A friend 

with an RV-9A went the same route as you and is very happy with the set up.



Not much activity on this message group. You might have better luck on Van's 

Air Force web site, http://www.vansairforce.net/. There is always lots going 

on that site, check out this link, 

http://www.vansairforce.com/community/search.php?searchid=3368738,



Good luck, keep building,



Mike

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Dale Ensing

Joined: 11 Jan 2006
Posts: 571
Location: Aero Plantation Weddington NC

Posted: Tue Feb 26, 2008 3:38 am Post subject: Firewall foreward cooling air needs

FWIW  if I am understanding correctly.....  The heat muffs are really not 

like a muffler internally. There are no baffles. I have two heat muffs in 

tantum on my RV-6A to maximize heat which has worked very well now for three 

years. I don't think using preheated air is a problem.

Dale Ensing



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_________________
Dale Ensing
RV-6A
Aero Plantation
Weddington NC

recapen(at)earthlink.net
Guest

Posted: Tue Feb 26, 2008 4:36 am Post subject: Firewall foreward cooling air needs

Dale,



I'm just going with what Larry Vetterman told me 'constant individual cooling air'.  They may or may not have baffles - but now I'm gonna look.



Ralph



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recapen(at)earthlink.net
Guest

Posted: Tue Feb 26, 2008 4:40 am Post subject: Firewall foreward cooling air needs

I actually do want them hot.  I'm just going with what Larry Vetterman provided me - 'constant individual cooling air'.

If I don't get enough heat, I'll consider the SS Scrubbies or a wire wrap coil.



It's an older (small-tail) 6A.



I'll check out Doug's area.....



--

aurbo(at)ak.net
Guest

Posted: Tue Feb 26, 2008 6:25 am Post subject: Firewall foreward cooling air needs

Ralph,



I agree with Dale. I just installed two of those Van's type heat muffs and 

they did not have any internal baffles. The outlet air does have a  plate in 

it with a bunch of small holes punched in it. I suppose that is to slow the 

air down a little so it will have a chance to get warm.



I have heard that it is best to install the muff with the inlet air the 

farthest down on the pipe and the outlet air up. I guess because heated air 

rises, Maybe??



I installed two power port outlets (cigarette lighters) in the airplane so 

the wife and I can wear electrically heated vests. I want to be warm and I 

have never been too impressed with aircraft heaters. Even in the summer it 

gets cold in Alaska especially at altitude.



Mike



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recapen(at)earthlink.net
Guest

Posted: Tue Feb 26, 2008 7:16 am Post subject: Firewall foreward cooling air needs

Mike,



Thanks for your response.



My heater/mufflers are made by Aircraft Exhaust Technologies for Larry Vetterman's systems.  When they're not heating the cabin, the heated air flows out the valve dump.  The requirement is that they always have to have air flowing over them and they can't be run in series.  I've read that they do provide plenty of heat.



Sorry for the confusion - I think I will be OK with the setup.



Ralph



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aurbo(at)ak.net
Guest

Posted: Wed Feb 27, 2008 7:05 am Post subject: Firewall foreward cooling air needs

Ralph,



I took the time to look at Vetterman's web site. Damn fine product.



Build on.



Mike



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