Lower valve covers and heat reduction..... Question
#16
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Stedge, those sheilds are .....aluminium (correct Bill) which disperses the heat prior to cooking the V.cover. And as far as the wrap, Roberts correct, that header wrap will rust a set out in no time. Yoy'd be better to get the Jet hot coated and go for the heat shields. I did my cover gaskets recently and they are bone dry still. The only thing I disagreed with on I think it was that P-car DIY was that the author recommended coating the gaskets in oil before installing them in the cover......? Why? Won't that just lead to the gasket drying out and or allowing new oil to follow the oil on the gasket and right out the cover..? Just my .02 cents
#17
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Originally Posted by 993inNC
The only thing I disagreed with on I think it was that P-car DIY was that the author recommended coating the gaskets in oil before installing them in the cover......? Why? Won't that just lead to the gasket drying out and or allowing new oil to follow the oil on the gasket and right out the cover..? Just my .02 cents
cheers
Mal
#18
An old British (both car and person) mechanic passed on a trick he used for those total loss oil lubricated vehicles the British used to sell in the 50-70's. He put a glaze of wheel grease around the rubber gasket for the valve cover. This also had the benefit of holding the gasket in place while you got the cover in place. The wheel grease doesn't thin very much when it gets hot, so it isn't as likely to let the motor oil out. Just another data point, for what it's worth (I know, nothing).
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Originally Posted by Robert Henriksen
In the SRF world, the only people willing to tape their header are the ones willing to shell out > $1k on a regular basis (I think, about once/season) to replace them. I'm told that the thermal wrap, while it does help contain the heat & keep it from cooking nearby components, also greatly accelerates the demise of the header material. Secondhand info, I'm not speaking from personal experience. Don't know if the SRF header material is markedly different from p-cars, etc.
The heat-sheet is a cool idea, but much more effective if made out of Ti..
#20
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Originally Posted by chris walrod
Robert and others, you are right-on about the header not lasting long. Yes, the thermal wrap works great, but headers dont last for more than a year or so of driving.
The heat-sheet is a cool idea, but much more effective if made out of Ti..
The heat-sheet is a cool idea, but much more effective if made out of Ti..
Chris,
I was looking at the Heet Sheet and noticed it was made from stainless steel...... Pretty hefty stuff.
Thanks again guys.
#21
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Originally Posted by Scott C
Will do..... Maybe we can get Gert and delanobe to meet up as well.
#22
I would think the best material would be carbon fiber. As it does not transfer heat (compared to aluminum or allow steel), even thought it is black and be more apt to get hot due to radiant heat. The aluminum can still get hot (radiant heat from the headers and convection heating from the hot air off the headers) and radiate the heat back to the valve cover. And for the **** retentive weight / cool factor it would be the lightest also.
Chris, you have much more experience with CF (since it is not allowed in our series very much), it this contrary to your experience?
Dan
Dan
Chris, you have much more experience with CF (since it is not allowed in our series very much), it this contrary to your experience?
Dan
Dan
#23
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Originally Posted by duc916
I would think the best material would be carbon fiber. As it does not transfer heat (compared to aluminum or allow steel), even thought it is black and be more apt to get hot due to radiant heat. The aluminum can still get hot (radiant heat from the headers and convection heating from the hot air off the headers) and radiate the heat back to the valve cover. And for the **** retentive weight / cool factor it would be the lightest also.
Chris, you have much more experience with CF (since it is not allowed in our series very much), it this contrary to your experience?
Dan
Chris, you have much more experience with CF (since it is not allowed in our series very much), it this contrary to your experience?
Dan
For areas near turbos, headers and crossover tubes, we have found Ti sheeting is still best for heat rejection. Not saying there isnt a better material, but given cost vs. availablilty vs. workability, Ti, so far, is best from all standpoints (for us). It is difficult to machine due to its work hardening personality, but we keep the Ti design criteria in the fabricated catagory
#24
Chris,
That is very interesting. The reason I figured the CF would work is I have CF exhaust cans on my Ducati and have seen them on a CRF450. The can is warm to the touch, but never as hot as aluminum or stainless steel cans after a ride.
We have used them for heat shields above the exhaust below the valve cover for 24-hour of Lemans with no issue, but I have no knowledge of what resin they where constructed with.
Do you have coefficient of thermal conductivity for the CF, I have data for Ti. I would expect the coefficient is magnitudes larger for Ti vs. CF.
Dan
That is very interesting. The reason I figured the CF would work is I have CF exhaust cans on my Ducati and have seen them on a CRF450. The can is warm to the touch, but never as hot as aluminum or stainless steel cans after a ride.
We have used them for heat shields above the exhaust below the valve cover for 24-hour of Lemans with no issue, but I have no knowledge of what resin they where constructed with.
Do you have coefficient of thermal conductivity for the CF, I have data for Ti. I would expect the coefficient is magnitudes larger for Ti vs. CF.
Dan
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Originally Posted by duc916
Do you have coefficient of thermal conductivity for the CF, I have data for Ti. I would expect the coefficient is magnitudes larger for Ti vs. CF.
Dan
Dan
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Following is something I found online: I will find out more tomorrow..
Properties for Carbon Fiber
Property Value
Material XAS,HTA,T300 34-700, T650/35 UMS2526 HM HS40 P25 P100 F180 F500
Coefficient of thermal expansion - Longitudinal x10-6 K-1 -0.1to-0.5 -0.6 -0.7 -1.3 -0.5 - -1.5
Coefficient of thermal expansion - Transverse x10-6 K-1 +26 - +37 +25
Thermal Conductivity W m-1 K-1
Properties for Carbon Fiber
Property Value
Material XAS,HTA,T300 34-700, T650/35 UMS2526 HM HS40 P25 P100 F180 F500
Coefficient of thermal expansion - Longitudinal x10-6 K-1 -0.1to-0.5 -0.6 -0.7 -1.3 -0.5 - -1.5
Coefficient of thermal expansion - Transverse x10-6 K-1 +26 - +37 +25
Thermal Conductivity W m-1 K-1