Joez intake concerns...
02-22-07, 11:16 AM
#91
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I found this alternative but it isn't pretty.
If I go with tape Ill definitely have to paint it. Way to shinny. But wouldn't this cancel the protection of direct radiation heat?
I'm still looking for some ceramic thermal paint. Anyone know what kind of paint Joe Z uses for his black satin finish? Any ceramic resin in it?
If I go with tape Ill definitely have to paint it. Way to shinny. But wouldn't this cancel the protection of direct radiation heat?
I'm still looking for some ceramic thermal paint. Anyone know what kind of paint Joe Z uses for his black satin finish? Any ceramic resin in it?
02-22-07, 10:48 PM
#93
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Joe Z uses a special liquid etching process which essentially dulls a polished intake to a satin finish.
Then from there it gets Anodized.
From Wikipedia, the free encyclopedia
Anodising, or anodizing, is a technique used to coat the surface of a metal (usually Aluminum or Titanium) with an oxide layer. It may be used to increase corrosion resistance, increase wear resistance, allow dyeing or prepare the surface for other processes and coatings. Anodization changes the microscopic texture of the surface and can change the crystal structure of the metal near the surface. The process derives its name from the fact that the part to be treated forms the anode portion of an electrical circuit in this electrolytic process.
Anodisation is frequently used to protect aluminium and titanium from abrasion and corrosion and to allow it to be dyed in a wide range of colors.
Anodising, or anodizing, is a technique used to coat the surface of a metal (usually Aluminum or Titanium) with an oxide layer. It may be used to increase corrosion resistance, increase wear resistance, allow dyeing or prepare the surface for other processes and coatings. Anodization changes the microscopic texture of the surface and can change the crystal structure of the metal near the surface. The process derives its name from the fact that the part to be treated forms the anode portion of an electrical circuit in this electrolytic process.
Anodisation is frequently used to protect aluminium and titanium from abrasion and corrosion and to allow it to be dyed in a wide range of colors.
In order for the air to heat up to a dangerous level, you would need flames buring around the intake surface.
Joe Z
02-23-07, 05:16 PM
#94
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You could have flames around it and it still won't transfer much heat. Not enough mass and not enough surface area.
A couple of really important issues are getting missed in this discussion. Heat is kinetic energy in a gas. Any time you swat a gas molecule it gains heat because it has more kinetic energy. Charle's Law is pretty clear about this. Sorry to **** in the Wheaties here, but the compressor blade temperature in a compressor has almost nothing to do with the output temperature . The pressure ratio determines output temperature, and the efficiency of the compressor determines how much energy you put into the process vs. how much kinetic energy remains in the gas after it has been accelerated.
So, what is really important to heat transfer? Surface area, thermal energy, and the relative masses of the two media. We already know the mass of the air in a 1 foot x 3" pipe isn't a lot. We know the mass of the pipe is about 0.680 Kg. So the tube weighs a lot more than the air at rest. However, because the air is moving from one end to the other, the air's mass is not fixed. I have a spreadsheet that lets me figure out actual flows based on Ve in any displacement engine, but without getting into the nitty gritty, the mass of the air moving into the engine, even at idle, isn't exactly small.
The problem at idle is resident time. Because the flow is small, the air in the tube is resident far longer than any other time. So sitting at a traffic light, you have the engine bay without any scavenging from forward motion, and you have the air in the pipe moving at a relatively slow speed. This makes one think intuitively this must be a bad situation. It's not. Here's why: as soon as that air moves from the intake pipe side (at atmospheric pressure) to the manifold side (at 28" of vacuum), any temperature the air might have absorbed from the tube is lost. Why? Because air moving from high pressure to low pressure loses temperature (Charle's Law again). So there's just no way for the intake to really cause any kind of grief in the period of time it passes through the intake because the throttleplate is going to pull all the temperature out of the air anyway.
Add to this, we have a 1 pound difference between the OEM plastic and any aluminium pipe, and honestly, I'll take the aluminium every time. Why? Because there is less mass to heat and less mass to cool. The knife cuts BOTH ways on this. IMHO, adding thermal wraps will only be helpful until the underhood temperature normalises, then all the wrap will do is slow the cooling process. Wraps can only slow heat tranfer, they can't eliminate it. If the wrap itself gains enough temperature to transfer heat to the inside of the tube, you just extend the cooling phase before the intake temperatures normalise. Again, it cuts both ways unless you can be certain you will be able to keep the outside of the wrap at a reasonably low temperature, or you want to really dramatically increase the mass of the system to further slow the process. And ceramic coatings are by far superior to any wraps for a bunch of reasons completely outside this discussion.
Wraps and coatings work wonderfully on exhausts primarily because they maintain the energy, and the energy is fundamental to pushing atmospheric pressure out of the pipe to make room for the hot gases. We are not worried about maintaining the energy with temperature on the intake side. We do that with tuned lengths on the intake and exhaust, and with cam timing. Air has considerable inertia. Once we get it moving in the direction we want to go, it will continue in that direction whether we expected it or not.
So the other pieces of this are the surface area and the thermal energy. While it is true the pipe feels hotter than the plastic, you don't know if it really is until you put a thermometer on them. Saying the aluminium feels hotter than the plastic doesn't mean much at all.
Also, the relative thermal energies here are very small on the intake side. Maybe we have 100F difference between the tube's temperature and OAT. Because we only have the surface area of the inside of the tube (113in^2 per foot), AND the air at the contact point is the slowest moving air (because it's boundary layer air and wants to stick to the surface, not really move at all) the amount of heat transfer is going to be tiny. Yes, the air will conduct some heat (and that heat also thins the boundary layer, but that's another discussion) while it traverses the tube, but as I said before, the thermal gain will easily be offset by the throttleplate.
At WOT, the mass of the airflow is pretty substantial. Look at it this way: your air/fuel ratio is a ratio of masses. If your engine is using 250cc/min of fuel per cylinder (pretty easy to do at WOT) and gasoline weighs ~740 grams per litre, that's roughly 185 grams of fuel per minute. You need ~13.2 times that mass in air, or about 2.4 Kg per minute per cylinder or 14.7 Kg total. That mass of air compared to our measly 0.680 Kg air pipe means not much heat will be transferred to the air.
Lastly, there are three ways heat moves. Convection, conduction, and radiation. Radiation is such a a miniscule factor as to be a non-player in this scenario. The scenario here is the tube conducting heat from outside sources and convecting it to the air on the inside. Again, with the relative areas and masses, I really don't think it's a significant problem in the real world.
I will add one thing - any intake pulling air from the engine compartment isn't well thought out. Consider roughly 1/3 of the available heat of combustion goes to kinetic energy, 1/3 goes to exhaust, and 1/3 goes to the cooling system. The engine compartment sits right behind the device responsible for removing 1/3 of the heat (or ~306 hp worth) from the system. It's definitely not the place you'll find the most dense air molecules around the car.
A couple of really important issues are getting missed in this discussion. Heat is kinetic energy in a gas. Any time you swat a gas molecule it gains heat because it has more kinetic energy. Charle's Law is pretty clear about this. Sorry to **** in the Wheaties here, but the compressor blade temperature in a compressor has almost nothing to do with the output temperature . The pressure ratio determines output temperature, and the efficiency of the compressor determines how much energy you put into the process vs. how much kinetic energy remains in the gas after it has been accelerated.
So, what is really important to heat transfer? Surface area, thermal energy, and the relative masses of the two media. We already know the mass of the air in a 1 foot x 3" pipe isn't a lot. We know the mass of the pipe is about 0.680 Kg. So the tube weighs a lot more than the air at rest. However, because the air is moving from one end to the other, the air's mass is not fixed. I have a spreadsheet that lets me figure out actual flows based on Ve in any displacement engine, but without getting into the nitty gritty, the mass of the air moving into the engine, even at idle, isn't exactly small.
The problem at idle is resident time. Because the flow is small, the air in the tube is resident far longer than any other time. So sitting at a traffic light, you have the engine bay without any scavenging from forward motion, and you have the air in the pipe moving at a relatively slow speed. This makes one think intuitively this must be a bad situation. It's not. Here's why: as soon as that air moves from the intake pipe side (at atmospheric pressure) to the manifold side (at 28" of vacuum), any temperature the air might have absorbed from the tube is lost. Why? Because air moving from high pressure to low pressure loses temperature (Charle's Law again). So there's just no way for the intake to really cause any kind of grief in the period of time it passes through the intake because the throttleplate is going to pull all the temperature out of the air anyway.
Add to this, we have a 1 pound difference between the OEM plastic and any aluminium pipe, and honestly, I'll take the aluminium every time. Why? Because there is less mass to heat and less mass to cool. The knife cuts BOTH ways on this. IMHO, adding thermal wraps will only be helpful until the underhood temperature normalises, then all the wrap will do is slow the cooling process. Wraps can only slow heat tranfer, they can't eliminate it. If the wrap itself gains enough temperature to transfer heat to the inside of the tube, you just extend the cooling phase before the intake temperatures normalise. Again, it cuts both ways unless you can be certain you will be able to keep the outside of the wrap at a reasonably low temperature, or you want to really dramatically increase the mass of the system to further slow the process. And ceramic coatings are by far superior to any wraps for a bunch of reasons completely outside this discussion.
Wraps and coatings work wonderfully on exhausts primarily because they maintain the energy, and the energy is fundamental to pushing atmospheric pressure out of the pipe to make room for the hot gases. We are not worried about maintaining the energy with temperature on the intake side. We do that with tuned lengths on the intake and exhaust, and with cam timing. Air has considerable inertia. Once we get it moving in the direction we want to go, it will continue in that direction whether we expected it or not.
So the other pieces of this are the surface area and the thermal energy. While it is true the pipe feels hotter than the plastic, you don't know if it really is until you put a thermometer on them. Saying the aluminium feels hotter than the plastic doesn't mean much at all.
Also, the relative thermal energies here are very small on the intake side. Maybe we have 100F difference between the tube's temperature and OAT. Because we only have the surface area of the inside of the tube (113in^2 per foot), AND the air at the contact point is the slowest moving air (because it's boundary layer air and wants to stick to the surface, not really move at all) the amount of heat transfer is going to be tiny. Yes, the air will conduct some heat (and that heat also thins the boundary layer, but that's another discussion) while it traverses the tube, but as I said before, the thermal gain will easily be offset by the throttleplate.
At WOT, the mass of the airflow is pretty substantial. Look at it this way: your air/fuel ratio is a ratio of masses. If your engine is using 250cc/min of fuel per cylinder (pretty easy to do at WOT) and gasoline weighs ~740 grams per litre, that's roughly 185 grams of fuel per minute. You need ~13.2 times that mass in air, or about 2.4 Kg per minute per cylinder or 14.7 Kg total. That mass of air compared to our measly 0.680 Kg air pipe means not much heat will be transferred to the air.
Lastly, there are three ways heat moves. Convection, conduction, and radiation. Radiation is such a a miniscule factor as to be a non-player in this scenario. The scenario here is the tube conducting heat from outside sources and convecting it to the air on the inside. Again, with the relative areas and masses, I really don't think it's a significant problem in the real world.
I will add one thing - any intake pulling air from the engine compartment isn't well thought out. Consider roughly 1/3 of the available heat of combustion goes to kinetic energy, 1/3 goes to exhaust, and 1/3 goes to the cooling system. The engine compartment sits right behind the device responsible for removing 1/3 of the heat (or ~306 hp worth) from the system. It's definitely not the place you'll find the most dense air molecules around the car.
Last edited by lobuxracer; 02-23-07 at 06:20 PM.
02-24-07, 08:56 AM
#95
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Wow. I have to admit guys, I took my time reading the above post. I really enjoy professional input like this one. Knowledge + reasoning + numbers. Can't get better than this.
thanks lobuxracer!
thanks lobuxracer!
02-24-07, 11:32 AM
#96
I will add one thing - any intake pulling air from the engine compartment isn't well thought out. Consider roughly 1/3 of the available heat of combustion goes to kinetic energy, 1/3 goes to exhaust, and 1/3 goes to the cooling system. The engine compartment sits right behind the device responsible for removing 1/3 of the heat (or ~306 hp worth) from the system. It's definitely not the place you'll find the most dense air molecules around the car.
02-28-07, 12:33 PM
#97
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I used a Thermotec sleeve on my S2000's AEM CAI, but it didn't do a damn thing.
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