tion
Just got it firing!
Had a 18ga. stainless steel plate cut for me than I rolled the edges. Covered up the unfinished look of the bare cat.
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Cat Shield
- Thread startertion
- Start date
That looks excellent.
Any concern about additional heat containment?
Any concern about additional heat containment?
A beautiful, clean look
Albertasaurus
Just got it firing!
Looks great, but would it interfere with the operation of an OEM center stand?
tion
Just got it firing!
I don't have a center stand so I don't know. It is about 1/4" off of the cat and under the pipe shield and the black muffler shield.
tion
Just got it firing!
I don't think so. They're is a 1/4" air gap. The first design had a resin eagle superglue on it with no problems. No discoloring of the stainless. I bet the hottest part is on the top of the cat.
tion
Just got it firing!
That is nice but mine keeps the black muffler shield. What do they get for them?
tion
Just got it firing!
I always like a good reason to take a spin and I'm sure you are very knowledgable but please don't state things as fact when they are opinions. So in fahrenheit here we go, cold temps and then after a 30 minute ride and bike at idle. Measured with an IR digital thermometer. Gold cylinder head cold 83.0, hot 150.1. Exhaust pipe at head C= 82.7, H =190.4. Exhaust shield at head C= 81.8, H 152.3.
My shield C= 80.1, H = 104.3. Muffler C = 81.2, H = 108.8. Factory exhaust pipe shield near my shield C = 80.1, H = 105.1.
Regards.
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I’m sorry. This is not an opinion but rather established fact. I was speaking in terms of the exhaust pipe, not the exhaust port at the head. The dissipation of the heat at the exhaust port is excellent as it receives maximum air cooling under operation. It‘s the design.
By covering the CAT, you are restricting the airflow to the HOTTEST PART of the motorcycle exhaust. I make no judgement about this one way or the other. It was not meant to be a pejorative.
The internal temperatures at the CAT during normal operating engine speeds, will be the hottest as further exothermic oxidation reactions are taking place there. This is why normal expected variances are about 150-300 degrees F increase in temperature post CAT.
Do not presume that because you have an IR thermometer, that the readings you take at the moment you take them, actually indicate real world operating temperatures in real world running conditions. You are measuring residual heat in static conditions.
Yes you have a nice looking piece of “bling” that you fabricated, congratulations. However I assure you that it will RAISE the temperature of the CAT. It’s simple physics. Less air flow, equals less heat being removed. You don’t add cold to something. You remove heat. This is physics.
I cannot say definitively if this increase in temperature will or will not result in issues down the road. That remains to be seen. I can stand firm on my statement that the temperature will substantially increase there though and will clearly become the hottest part of the operating motorcycle exhaust. I have no doubt about it.
Regards to you too.
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There's more to cat converters than simple external convection. Automotive cats have shields for multiple reasons.I’m sorry. This is not an opinion but rather established fact. ... This is physics.
Those heat sheilds on automobiles are there to protect the vehicle, and if you park on grass, you don't start a fire. Cats get very hot on a car and there isn't great air flow to them so the shields protect the vehicle from the heat. On the bike, increased airflow helps to cool the darn thing off. If you don't want to believe what someone with years of experience tries to teach you, then just ignore the response.
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GuidoVeloce said:
There's more to cat converters than simple external convection. Automotive cats have shields for multiple reasons.
—————
Hello.
I help many people here every week. Sorry that the way I do this somehow triggers you.
My point was very polite and simple and was about MOTORCYCLES as this is my area of expertise. I take my car to car mechanics. I’m a motorcycle mechanic and a darn good one too:
If you cover an air cooled component, thereby reducing its thermal transference ability of moving excess heat to the flowing air, it will get much hotter.
In the case of a motorcycle CAT, much much hotter during operation.
It was only meant as a FYI to those considering it. It wasn’t a pejorative, a judgement, an indicator of an unsound mind, or anything else.
However it seems that I now have 2 people hellbent on being rude and argumentative. Ok. Whatever. Have a good time…
Suggestion: please - Click my name, then click IGNORE. You will be doing me a huge favor. Thanks.
No good deed or effort around here goes unpunished…
There's more to cat converters than simple external convection. Automotive cats have shields for multiple reasons.
—————
Hello.
I help many people here every week. Sorry that the way I do this somehow triggers you.
My point was very polite and simple and was about MOTORCYCLES as this is my area of expertise. I take my car to car mechanics. I’m a motorcycle mechanic and a darn good one too:
If you cover an air cooled component, thereby reducing its thermal transference ability of moving excess heat to the flowing air, it will get much hotter.
In the case of a motorcycle CAT, much much hotter during operation.
It was only meant as a FYI to those considering it. It wasn’t a pejorative, a judgement, an indicator of an unsound mind, or anything else.
However it seems that I now have 2 people hellbent on being rude and argumentative. Ok. Whatever. Have a good time…
Suggestion: please - Click my name, then click IGNORE. You will be doing me a huge favor. Thanks.
No good deed or effort around here goes unpunished…
Last edited:
tion
Just got it firing!
Airflow is a tricky thing. By having a smooth shield you create a low pressure zone on the outside as opposed to the high pressure zone on the inside caused by the irregular surface and the hot air may migrate from high pressure to low pressure zones. That would actually improve cooling. I don't know if that is true or not and I make no claim that it is.
Read the info from one of the many companies that make shields for cats and they all tell you that they don't increase temps. Also consider that car companies put shields on the bottoms of their cars to improve air flow. Finally look at trucks. By sticking big shields on the front and sides they increase the total area of the truck yet improve gas mileage through less drag. There are plenty of examples. Also seems Mistral thinks it is OK.
My point is this - you don't know that it restricts airflow and I don't know that it doesn't.
I'm traveling on business the next 3 weeks and then a week's vacation so I don't have time to pull the shield for a month and measure. By then this thread will be long forgotten. If anyone has a digital thermometer they could do the test. Temp stone cold then measure after 30 minute ride during idle. I think the temp on the top of the cat is the critical one. If the temps are different it doesn't matter - what is important is the delta T.
Respectfully, Dave
Read the info from one of the many companies that make shields for cats and they all tell you that they don't increase temps. Also consider that car companies put shields on the bottoms of their cars to improve air flow. Finally look at trucks. By sticking big shields on the front and sides they increase the total area of the truck yet improve gas mileage through less drag. There are plenty of examples. Also seems Mistral thinks it is OK.
My point is this - you don't know that it restricts airflow and I don't know that it doesn't.
I'm traveling on business the next 3 weeks and then a week's vacation so I don't have time to pull the shield for a month and measure. By then this thread will be long forgotten. If anyone has a digital thermometer they could do the test. Temp stone cold then measure after 30 minute ride during idle. I think the temp on the top of the cat is the critical one. If the temps are different it doesn't matter - what is important is the delta T.
Respectfully, Dave
Selkie
Just got it firing!
Very nice, but I have a center stand, will it work?
tion
Just got it firing!
I don't have a center stand so I can 't tell you. Mistral might. I just made a few because of the set up costs at the machine shop. Sold the extras and that was it for me.
