Today's Message Index:
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1. 10:42 AM - heat shields (Ken)
2. 05:21 PM - Re: heat shields (n801bh@netzero.com)
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--> Engines-List message posted by: Ken <klehman@albedo.net>
Would anyone have any rules of thumb on how close silicone radiator
hoses and silicone air ducts can safely be to exhaust stacks before
shielding or insulation is needed?
So far I've shielded areas that are closer than 3 or 4 inches. I am
wondering if I should wrap some glass cloth or fiberfrax on a few other
areas. Silicone is generally good for over 400F although I'm not sure
how well it conducts surface radiant heat away.
thank you for any comments
Ken
Message 2
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| Subject: | Re: heat shields |
--> Engines-List message posted by: "n801bh@netzero.com" <n801bh@netzero.com>
Would anyone have any rules of thumb on how close silicone radiator
hoses and silicone air ducts can safely be to exhaust stacks before
shielding or insulation is needed?
So far I've shielded areas that are closer than 3 or 4 inches. I am
wondering if I should wrap some glass cloth or fiberfrax on a few other
areas. Silicone is generally good for over 400F although I'm not sure
how well it conducts surface radiant heat away.
thank you for any comments
Ken
///////////////////////////////////////////////////////////////////////////////////////////////////
Hi Ken. I guess the easiest way to get the point across about radiant heat from the exhaust system is this, Go to any electric stove. turn on the top burner and let it heat up. When it is glowing "red" hot that is about 1400 f degrees. Now remember your nifty EGT gauge shows 1450- 1500 f. The first foot or so of the exhaust system starting at the head is that temp. Take your hand and hold it over the stove burner and see how fast you move your hand away.<G>.. Your thoughts of 3-4" is a pretty good number to live by. Anything closer needs a heat shield to absorb the radiant heat and prevent scorching of componants. On my beast I protect the engine mounts, wires and any other thing that I don't want to get cooked. On my coolant lines leading to my radiator they are mounted clear of any excess heat source. The fact that coolant is flowing through them will help cool them but the surface may still get scorched if they are run real close to the exhaust pipes. I am coming up on 100 hours on my experimental and on every takeoff I run 1600f+ EGT temps, there is no sign of any heat related transfers that are degrading parts in the cowling. You can go the my web site www.haaspowerair.com and click on pics to see how I routed lines on the whole engine. You are wise to realize that radiant heat is a BIG factor in placing componants around the engine... Happy New Year guys..............
Ben Haas
N801BH
www.haaspowerair.com
Would anyone have any rules of thumb on how close silicone radiator
hoses and silicone air ducts can safely be to exhaust stacks before
shielding or insulation is needed?
So far I've shielded areas that are closer than 3 or 4 inches. I am
wondering if I should wrap some glass cloth or fiberfrax on a few other
areas. Silicone is generally good for over 400F although I'm not sure
how well it conducts surface radiant heat away.
thank you for any comments
Ken
///////////////////////////////////////////////////////////////////////////////////////////////////
Hi Ken. I guess the easiest way to get the point across about radiant heat from the exhaust system is this, Go to any electric stove. turn on the top burner and let it heat up. When it is glowing "red" hot that is about 1400 f degrees. Now remember your nifty EGT gauge shows 1450- 1500 f. The first foot or so of the exhaust system starting at the head is that temp. Take your hand and hold it over the stove burner and see how fast you move your hand away.G.. Your thoughts of 3-4" is a pretty good number to live by. Anything closer needs a heat shield to absorb the radiant heat and prevent scorching of componants. On my beastI protect the engine mounts, wires and any other thing that I don't want to get cooked. On my coolant lines leading to my radiator they are mounted clear of any excess heat source. The fact that coolant is flowing through them will help cool them but the surface may still get scorched if they are run real close to the exhaust pipes. I am coming up on 100 hours on my experimental and on every takeoff I run 1600f+ EGT temps, there is no sign of any heat related transfers that are degrading parts in the cowling. You can go the my web site www.haaspowerair.com and click on pics to see how I routed lines on the whole engine. You are wise to realize that radiant heat is a BIG factor in placing componants around the engine... Happy New Year guys..............
BenHaas
N801BH
www.haaspowerair.com
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