How close is too close?
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Senior User
Joined: Jun 2003
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From: Kannapolis NC
How close is too close?
I have noticed that the headers on my 351w which are ceramic coated are near to the distribution manifold of the brakes, maybe 1" at most. Does anyone have an opiniopn if this is too close and will cause a problem with heating the brake fluid? Thanks
Post Fiend
Joined: May 2008
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From: Poway, Ca.
1" is awful close - especially right after you stop and turn the engine off. You might want to move, shield, or insulate that line.
I believe that DOT 3 brake fluid has a boiling point up around 725+ degrees and it won't flash, but you still have the expansion and pressure problems associated with that much heat that close. Plus, I'm not sure how close that hot fluid is to any hoses or rubber plungers, but heat will effect them too.
J!
I believe that DOT 3 brake fluid has a boiling point up around 725+ degrees and it won't flash, but you still have the expansion and pressure problems associated with that much heat that close. Plus, I'm not sure how close that hot fluid is to any hoses or rubber plungers, but heat will effect them too.
J!
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From: Woodinville
You can wrap the headers with insulation tape for headers or you can move the manifold away from the headers. Another alternative is a little creative cutting with a piece of Stainless Steele sheet metal. Make a heat shield that can be bolted to the manifold bracket or the frame somewhere close. Do Not bolt the shield to the engine as it could vibrate loose or make noise. I learned that one the hard way. ;-)
Anyway take a look under any new truck and you can see heat shields bolted to the under side of the cab to keep the catalytic converter heat from scorching the carpet inside the cab. I little shield will go a long way. ;-)
Cyrus
_____________________
My Grandpa told me once that you have to learn by the mistakes of others because you will NOT live long enough to make them all yourself.
Anyway take a look under any new truck and you can see heat shields bolted to the under side of the cab to keep the catalytic converter heat from scorching the carpet inside the cab. I little shield will go a long way. ;-)
Cyrus
_____________________
My Grandpa told me once that you have to learn by the mistakes of others because you will NOT live long enough to make them all yourself.
Logistics Pro
Joined: Feb 2005
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From: Upper Left Coast
1" is awful close - especially right after you stop and turn the engine off. You might want to move, shield, or insulate that line.
I believe that DOT 3 brake fluid has a boiling point up around 725+ degrees and it won't flash, but you still have the expansion and pressure problems associated with that much heat that close. Plus, I'm not sure how close that hot fluid is to any hoses or rubber plungers, but heat will effect them too.
J!
I believe that DOT 3 brake fluid has a boiling point up around 725+ degrees and it won't flash, but you still have the expansion and pressure problems associated with that much heat that close. Plus, I'm not sure how close that hot fluid is to any hoses or rubber plungers, but heat will effect them too.
J!
I'll agree with Jules about 1" being too close! 725* sounds a little high though (which makes this problem even more important to fix)
Understanding Brake Fluid - RPMnet.com tech articles - by AFCO racing
Depending on the water content of the fluid it could be as low as 284*F or as high as 401*F for DOT3.
You really should make up some sort of heat shield since your manifolds can get pretty hot after a long pull and anything 1" away will get a lot of heat just from the Infrared radiation after you stop.
Regards,
Rick
Post Fiend
Joined: May 2008
Posts: 7,641
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From: Poway, Ca.
Da Doy
J!
PS Hmmm, wonder where I saw 725??????
Logistics Pro
Joined: Feb 2005
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From: Upper Left Coast
I wonder if that's the flash point?
edit: Well it's not the flash point. It could be the "auto-ignition" point though Flash point it the temp where a vapor is present that can be ignited. that's not much above the boiling point.
The autoignition point of DOT3 is around 520* F
edit: Well it's not the flash point. It could be the "auto-ignition" point though Flash point it the temp where a vapor is present that can be ignited. that's not much above the boiling point.
The autoignition point of DOT3 is around 520* F
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Hotshot
Joined: Oct 2004
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From: Durham NC
DON'T wrap your headers! That's the fastest way to kill a good set of headers, the header manufacturers LOVE seeing a wrapped set, that's a replacement purchase in the making.
I reall doubt you will have a problem but you could put a heat shield between the header and the block. I'd use aluminum as my shield material, it has much better heat conducting properties than SS. Attach the shield to the firewall or whatever the block is attached to with large tabs (again to conduct the heat to a cooler surface) and keep it at least 1/2" away from the lines. It should be at least twice the size of what you are protecting. Allow as much air circulation as possible around the shield.
I reall doubt you will have a problem but you could put a heat shield between the header and the block. I'd use aluminum as my shield material, it has much better heat conducting properties than SS. Attach the shield to the firewall or whatever the block is attached to with large tabs (again to conduct the heat to a cooler surface) and keep it at least 1/2" away from the lines. It should be at least twice the size of what you are protecting. Allow as much air circulation as possible around the shield.
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From: AZ
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From: Woodinville
Yes I agree that SS is a poor conductor of heat but that is not what a heat "shield" is for. The circulating air gap between the two objects stops the direct conduction transfer of heat. What the heat shield does is stop the radiant transfer of heat. The air moving on both sides of the SS heat shield is enough to bring the temperature down to a safe level.
The reason I use SS over Aluminum is it looks much nicer when it is polished and it stays nice looking even after a lot of years.
Aluminum on the other hand will do the same job but if you want it to stay nice looking you will have to clear coat it and being that close to the header it will burn off.
Sense you need a heat shield and not a heat sink I think SS would be a better choice. Also Polished SS reflects infrared radiation better than coated aluminum.
Cyrus Cheers
_____________________
My Grandpa told me once that you have to learn by the mistakes of others because you will NOT live long enough to make them all yourself.
The reason I use SS over Aluminum is it looks much nicer when it is polished and it stays nice looking even after a lot of years.
Aluminum on the other hand will do the same job but if you want it to stay nice looking you will have to clear coat it and being that close to the header it will burn off.
Sense you need a heat shield and not a heat sink I think SS would be a better choice. Also Polished SS reflects infrared radiation better than coated aluminum.
Cyrus Cheers
_____________________
My Grandpa told me once that you have to learn by the mistakes of others because you will NOT live long enough to make them all yourself.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
I wonder if that's the flash point?
edit: Well it's not the flash point. It could be the "auto-ignition" point though Flash point it the temp where a vapor is present that can be ignited. that's not much above the boiling point.
The autoignition point of DOT3 is around 520* F
edit: Well it's not the flash point. It could be the "auto-ignition" point though Flash point it the temp where a vapor is present that can be ignited. that's not much above the boiling point.
The autoignition point of DOT3 is around 520* F
Just to clarify...I said "Boiling Point." That is where a liquid turns to vapor. DOT 3 minimum "boiling" temp is 284dgf.
Nothing to do with it igniting, fire and all that.
Flash point is the lowest temperature that a vapor will ignite.
Two completely different things.
Don't know where I got the 750...just AFU I guess.
J!
Hotshot
Joined: Oct 2004
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From: Durham NC
Yes, all headers including SS. I read that in an article on headers in a magazine where they were interviewing 3 header manufacturers, all agreed. Has to do with holding in the heat and differential heating/warping cracking the pipes IIRC.
Fleet Owner
Joined: Jul 2004
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From: NM
Cyrus is correct, the idea is to block radiated energy. The shield should just block line-of-sight between the header and the brake parts, not be tight-fitting. I've seen where people glue header-wrap type insulation on the back side of a shield, this is a good bet and helps prevent vibration or rattling. "Breaking" (creasing) the shield to stiffen it will also help with that.