heat shield test
Discussion
I feel that a few people are a bit concerned about how well the heat shields that I am making, are going to work due to the fact that they are mounted on the exhaust itself,
So I managed to get my hands on a laser temperature meter,so have done a couple of tests this afternoon to see how much heat my heat shields are absorbing from being mounted to the exhaust pipe
I removed one heat shield and wrapped a strip of exhaust heat bandage 2” wide around the pipe, 1 layer, and then clamped the shield back over the top of the bandage, the other shield was left fitted directly on the exhaust,I should also note that my exhaust is cam coated.
If we call the shield fitted directly onto the exhaust A, and the shield fitted on topof the exhaust wrap B, then I found that
at tickover, temp gauge at 55dg A was 25 dg, B was 23dg, exhaust was 150dg
took it for a run and let it tick over some more to heat up,readings taken with engine still running, fans off,
temp guage 80dg A was 80dg, B was 58dg exhaust was 260 dg
turned engine off, after 2-3minutes
A was 60dg, B was 45dg and exhaust was 160dg.
Therefor the best thing is to put a strip of exhaust wrap under each clip, as this is the only contact area with the exhaust, and reduces the amount of heat being absorbed by the heat shield.
I should have done this first really, but we live and learn!
So I managed to get my hands on a laser temperature meter,so have done a couple of tests this afternoon to see how much heat my heat shields are absorbing from being mounted to the exhaust pipe
I removed one heat shield and wrapped a strip of exhaust heat bandage 2” wide around the pipe, 1 layer, and then clamped the shield back over the top of the bandage, the other shield was left fitted directly on the exhaust,I should also note that my exhaust is cam coated.
If we call the shield fitted directly onto the exhaust A, and the shield fitted on topof the exhaust wrap B, then I found that
at tickover, temp gauge at 55dg A was 25 dg, B was 23dg, exhaust was 150dg
took it for a run and let it tick over some more to heat up,readings taken with engine still running, fans off,
temp guage 80dg A was 80dg, B was 58dg exhaust was 260 dg
turned engine off, after 2-3minutes
A was 60dg, B was 45dg and exhaust was 160dg.
Therefor the best thing is to put a strip of exhaust wrap under each clip, as this is the only contact area with the exhaust, and reduces the amount of heat being absorbed by the heat shield.
I should have done this first really, but we live and learn!
Edited by clive f on Wednesday 10th January 18:56
Sounds like they work well! Could I persuade you to make a set for ACT manifolds in the future?
I've got exhaust gas temperature readings from my car of approximately 600c on full chat. (It only takes a few seconds for this to come down again) Obviously the manifold skin will be less than this, but they will hold the temperature they do have for a fair while.
BTW do you have a couple of feet of the exhaust wrap spare?
I've got exhaust gas temperature readings from my car of approximately 600c on full chat. (It only takes a few seconds for this to come down again) Obviously the manifold skin will be less than this, but they will hold the temperature they do have for a fair while.
BTW do you have a couple of feet of the exhaust wrap spare?
Your exhaust hardly had any heat in it at all in those tests, perhaps due to your ceramic coating. I'd expect to see rather more heat transfer for people with a standard (non-coated) exhaust. But by the same token, these are the people who stand to gain the most from your heat shield. Personally I wouldn't worry too much about conduction through the mounting. If you're looing for better gains, try lagging the underside of the heat shield if you haven't already.
Yes they do get hot, measurement at stationary is not very indicative (unfortunately) of the temps that can be reached. I could only make comparisons by deforming foam - taped to areas under the bonnet and looking to see if it had melted after a hot run - it would sit there all day ticking over on the drive but would be ash after a short thrash. I'm not talking about the ancilliary areas - but further away from the manifolds on the inner wings...
Dave
Dave
Spend; obviously the temperatures increase greatly when the car is being driven and the engine under load, rather than readings taken when stationary after driving, but also don`t forget that whilst the vehicle is moving you then have the airflow under the bonnet coming in through the front grill, this isn`t brilliant as we all know, but it does help.
Edited by clive f on Thursday 11th January 09:21
clive f said:
Spend; obviously the temperatures increase greatly when the car is being driven and the engine under load, rather than readings taken when stationary after driving, but also don`t forget that whilst the vehicle is moving you then have the airflow under the bonnet coming in through the front grill, this isn`t brilliant as we all know, but it does help.
Remember that the cooling air flow stops the moment the car stops, but the accumulated heat will still be blasting rounf the engine bay.
Yes Clive. I have had my own "laser" thermometer velcro'd in the boot for a few years, and was just passing on my experience of its limitations. The temperature readings you can take with the bonnet up are not in the same ball park as when running in anger. The radiated heat on full chat is intense - reflective surfaces are the best protection - just like getting sunburnt when there is a breeze, the airflow is not enough protection!
Dave
Dave
to true, quite agree with both of you, but short of stuffing my small young son with the heat meter in his hand under the bonnet and taking the car for a good run, these temperature readings are not going to be recorded without some serious hi tech monitoring equipment, via a laptop pc in the car
Edited by clive f on Thursday 11th January 10:49
I have done a fair bit of temperature testing and a good way is to use the ECU temp sender. Set to volts a digimeter will register a difference with the merest adjustment of throttle. Never tried the shields though, i prefer to monitor the road speed and adjust cooling fans between half and full, never sitting still without some on.
clive f said:
to true, quite agree with both of you, but short of stuffing my small young son with the heat meter in his hand under the bonnet and taking the car for a good run, these temperature readings are not going to be recorded without some serious hi tech monitoring equipment, via a laptop pc in the car
If it matters, it's fairly easy to fit temp tabs on the critical components to see what their peak temperature is, and you can get electronic thermometers with a remote display for a few quid. I often have half a dozen or so dotted around the engine bay and inside and outside the engine to see what's going on as the car is driving. Frankly this is overkill though, it's clear that the heat shield is making a significant difference, and who cares whether you know the effect to two decimal places?
GreenV8S said:
clive f said:
to true, quite agree with both of you, but short of stuffing my small young son with the heat meter in his hand under the bonnet and taking the car for a good run, these temperature readings are not going to be recorded without some serious hi tech monitoring equipment, via a laptop pc in the car
it's clear that the heat shield is making a significant difference, and who cares whether you know the effect to two decimal places?
Well said Peter, Its proven that it does the Job...Better than nothing that was there before and looks good to. It Bloody annoys me when an enthusiast makes something good and then gets aload of crap of people as if he was a Huge manufacturer who has all the answers.
BB
simon, and peter, thanks just repeating what I have posted on the chimeara forum, some may find this useful, as I tested the temperature of the heat sensor on the bottom of the swirl pot to see if the heat shield is doing what it is supposed to.
I tested this last night, went for a good run, and found that with the coolant temp guage reading 80dg, manifold 260dg, the heat sensor at the bottom of the swirl pot was 96dg.
after dinner, removed exhaust shield, repeated the above and found that the coolant guage 80dg, manifold 260dg and sensor was 116dg.
these give a guidline showing that the heat shield is doing what it is supposed to.
http://cgi.ebay.co.uk/A-pair-of-Exhau
I tested this last night, went for a good run, and found that with the coolant temp guage reading 80dg, manifold 260dg, the heat sensor at the bottom of the swirl pot was 96dg.
after dinner, removed exhaust shield, repeated the above and found that the coolant guage 80dg, manifold 260dg and sensor was 116dg.
these give a guidline showing that the heat shield is doing what it is supposed to.
http://cgi.ebay.co.uk/A-pair-of-Exhau
Not sure about the strips Pete, highest I could find only went to 290c - Im pretty sure without coating of manifolds you can see 700c in areas adjacent to ports & 500c around main cat.
I suspect Clives readings are not showing the benefits of shielding fully, but I also wonder where the heat will go.... ie reflective heat shield on wings & bonnet to reflect fglass make it like a big cooker. Remember the early criticisms of ceramic coating - heat will stay in the heads, in the exhaust.... I personally can understand that with internal ceramic coating the heat is forced out in the exhaust gasses (well as a best attempt at least).
Regarding Davids points, I dont think the rad fans have much effect - the scenarios I thought we were discussing is when the manifolds are very hot when the engine is being ~stressed~ & there is a lot of difference between @100c coolant and @1000c burnt charge. Isnt this where radiation starts, when heat cannot be dissipated via conduction / convection the surface radiates?
SIMON: what really gets my goat is people who try to throttle open discussion in a topic! PH has always been available for open discussion - if you dont agree with what somebody says then reply to it! If uou dont want discussion about a posting put it on the classifieds!
Dave
I suspect Clives readings are not showing the benefits of shielding fully, but I also wonder where the heat will go.... ie reflective heat shield on wings & bonnet to reflect fglass make it like a big cooker. Remember the early criticisms of ceramic coating - heat will stay in the heads, in the exhaust.... I personally can understand that with internal ceramic coating the heat is forced out in the exhaust gasses (well as a best attempt at least).
Regarding Davids points, I dont think the rad fans have much effect - the scenarios I thought we were discussing is when the manifolds are very hot when the engine is being ~stressed~ & there is a lot of difference between @100c coolant and @1000c burnt charge. Isnt this where radiation starts, when heat cannot be dissipated via conduction / convection the surface radiates?
SIMON: what really gets my goat is people who try to throttle open discussion in a topic! PH has always been available for open discussion - if you dont agree with what somebody says then reply to it! If uou dont want discussion about a posting put it on the classifieds!
Dave
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