Full Intercooler piping around $300
Cal gunna crush all competetors and put them outa business!!! hahahaa.. Serves them right SSHHHHEEEETTTTTT!!!! tryin to jack ppl for 600-800 bucks for piping!! Shove it up your A S S
Originally Posted by SuperHatch
I'm also going to have to go with AL as a better choice for IC piping myself, but I am curious to learn more. David, can you point me to some of these books you've read? I'd like to see their info. My reasoning for choosing AL is fairly simple, and this is it...
You are correct in saying that aluminum heats up faster than SS, this is due to it's higher thermal conductivity and lower heat capacity than SS. It accepts heat faster than SS and can hold less, so it reaches a given temp faster. The total stored heat energy in the AL will be lower than the SS given the same temperature, and this, combined with the ALs ability to heat up and cool down faster, the AL pipes will also dissipate this heat faster than the SS pipes.
While I agree that the "reflectivity" of the polished SS will reduce it's heat absorbtion, this is a minor consideration in this application.
The reflectivity will only reduce heat transfer cause by radiant heat transfer, it will not directly effect convective or conductive transfer. In this application, convective (air passing over the surface) and conductive (direct contact with a heat source) are the primary methods of heat transfer. This is simply due to the fact that radiant heat transfer is governed by an equation that is based on a difference of the temperatures after they are raised to the 4th power.
P = e * (sigma) * A * (T^4 - Tc^4) where...
P = Radiated Energy
A = Radiating area
(sigma) = Stefan's Constant 5.6703 x 10^-8 Watts/m^2 K^4
e = emissivity ( from 0 -> 1 ; 1 is for a perfect emitter)
T = temperature of the radiator (in degrees K)
Tc = temperature of the surroundings (in degrees K)
Assuming that the entire engine compartment is a perfect emitter (it's not), it's total surface area is 3 square meters, and that the temperature difference between the entire engine compartment and the piping is 800 degrees K (I sure hope it isn't), you will only end up with 0.2 Watts of heat energy being transferred. That ain't much.
Convection and conduciton are directly related to the difference in temperatures, and therefore the greater the temp difference the greater the heat transfer. Convection is an issue since the air is always moving through the engine compartment, and a lot of that air is hot from passing through the radiator and over the hot engine. However, convection doesn't directly care how shiney a surface is, but it does care how smooth a surface is and how big a surface is. The smoother the surface, the less heat will be transfered through convection due to less turbulance at the surface of the object being heated. Since most things that are polished are smooth, they have low convective heat transfer properties, but that fact that the AL dulls over time, doesn't matter as long as the surface stays smooth.
Conduction has very high heat transfer properties, but it happens through direct contact between 2 solids, but the majority of the IC piping is just hanging in the engine compartment, this makes conduciton negligable.
That leaves Convection as the primary form of heating the pipes. You have convection occuring on the outside of the pipes with the hot engine compartment air, and convection on the inside of the pipes with the (hopefully cooler) charge air. The velocity of the air inside the pipes is higher than the velocity of the air outside the pipes, so the heat taken out of the pipes will happen faster than the heat can be put back in by the engine compartment. Furthermore, since AL has a lower heat capacity, this cooling will happen FASTER than it would with SS.
Combine all these things and you have from my perspective, why AL is a better choice. I would like to see the evidence of your books to compare my thoughts to though.
- Steve
You are correct in saying that aluminum heats up faster than SS, this is due to it's higher thermal conductivity and lower heat capacity than SS. It accepts heat faster than SS and can hold less, so it reaches a given temp faster. The total stored heat energy in the AL will be lower than the SS given the same temperature, and this, combined with the ALs ability to heat up and cool down faster, the AL pipes will also dissipate this heat faster than the SS pipes.
While I agree that the "reflectivity" of the polished SS will reduce it's heat absorbtion, this is a minor consideration in this application.
The reflectivity will only reduce heat transfer cause by radiant heat transfer, it will not directly effect convective or conductive transfer. In this application, convective (air passing over the surface) and conductive (direct contact with a heat source) are the primary methods of heat transfer. This is simply due to the fact that radiant heat transfer is governed by an equation that is based on a difference of the temperatures after they are raised to the 4th power.
P = e * (sigma) * A * (T^4 - Tc^4) where...
P = Radiated Energy
A = Radiating area
(sigma) = Stefan's Constant 5.6703 x 10^-8 Watts/m^2 K^4
e = emissivity ( from 0 -> 1 ; 1 is for a perfect emitter)
T = temperature of the radiator (in degrees K)
Tc = temperature of the surroundings (in degrees K)
Assuming that the entire engine compartment is a perfect emitter (it's not), it's total surface area is 3 square meters, and that the temperature difference between the entire engine compartment and the piping is 800 degrees K (I sure hope it isn't), you will only end up with 0.2 Watts of heat energy being transferred. That ain't much.
Convection and conduciton are directly related to the difference in temperatures, and therefore the greater the temp difference the greater the heat transfer. Convection is an issue since the air is always moving through the engine compartment, and a lot of that air is hot from passing through the radiator and over the hot engine. However, convection doesn't directly care how shiney a surface is, but it does care how smooth a surface is and how big a surface is. The smoother the surface, the less heat will be transfered through convection due to less turbulance at the surface of the object being heated. Since most things that are polished are smooth, they have low convective heat transfer properties, but that fact that the AL dulls over time, doesn't matter as long as the surface stays smooth.
Conduction has very high heat transfer properties, but it happens through direct contact between 2 solids, but the majority of the IC piping is just hanging in the engine compartment, this makes conduciton negligable.
That leaves Convection as the primary form of heating the pipes. You have convection occuring on the outside of the pipes with the hot engine compartment air, and convection on the inside of the pipes with the (hopefully cooler) charge air. The velocity of the air inside the pipes is higher than the velocity of the air outside the pipes, so the heat taken out of the pipes will happen faster than the heat can be put back in by the engine compartment. Furthermore, since AL has a lower heat capacity, this cooling will happen FASTER than it would with SS.
Combine all these things and you have from my perspective, why AL is a better choice. I would like to see the evidence of your books to compare my thoughts to though.
- Steve
Buschur is 100% correct saying that SS is a much better choice for intercooler piping per above. Aluminum will get heat soaked quicker AND transfer more thermal energy to the charge air, do some heat transfer calcs since you seem to be up on your math and you will agree.
Titanium would be an even better choice, and a thermal barrier coating would further aid in making sure the temps stay low after exiting the intercooler.
If aluminum was a better choice at keeping the heat from the surrounding air from getting to what is inside the piping, then why is it used in radiators where we want the exact opposite to happen?
You want your intercooler piping to be an insulating barrier between the hot underhood air and the charge air.
Discussions like this are much more interesting when someone who is ejumicated joins in
You want your intercooler piping to be an insulating barrier between the hot underhood air and the charge air.
Discussions like this are much more interesting when someone who is ejumicated joins in
Haha, the irony. 
For those saying that the step in the lower intercooler piping will make or break the system as far as power goes, a step up to a larger cross-sectional area has a very low loss coefficient associated with it.
For those saying that the step in the lower intercooler piping will make or break the system as far as power goes, a step up to a larger cross-sectional area has a very low loss coefficient associated with it.
Okay, it’s been a while since I’ve used any heat transfer stuff. Things are clicking in my head again.
These are the assumptions for this scenario:
- engine bay is warmed up and at steady state temperature
- temperature of air passing through the pipe is lower than the engine bay
As stated above, the mode of heat transfer (hot always goes to cold) in this case is:
1) convection through the engine compartment air
2) conduction through the intercooler pipe material (think of this as our resistor)
3) convection to the air inside the pipes
Stainless steel has more resistance and will transfer heat slower over aluminum. Therefore, SS will transfer heat at a slower rate to the air passing through it. From a heat transfer perspective, SS would be the better material choice.
Now will how much difference this will make on our cars? I’m not sure if there would be a difference that’s noticeable. The only way to find out is to run an experiment!
These are the assumptions for this scenario:
- engine bay is warmed up and at steady state temperature
- temperature of air passing through the pipe is lower than the engine bay
As stated above, the mode of heat transfer (hot always goes to cold) in this case is:
1) convection through the engine compartment air
2) conduction through the intercooler pipe material (think of this as our resistor)
3) convection to the air inside the pipes
Stainless steel has more resistance and will transfer heat slower over aluminum. Therefore, SS will transfer heat at a slower rate to the air passing through it. From a heat transfer perspective, SS would be the better material choice.
Now will how much difference this will make on our cars? I’m not sure if there would be a difference that’s noticeable. The only way to find out is to run an experiment!
Originally Posted by mikesevo8
In other words, you want to get from the turbo outlet size (smaller) to the intercooler inlet size (larger) as quickly and
gracefully as possible, yes ???
gracefully as possible, yes ???
Originally Posted by marksae
Okay, it’s been a while since I’ve used any heat transfer stuff. Things are clicking in my head again.
These are the assumptions for this scenario:
- engine bay is warmed up and at steady state temperature
- temperature of air passing through the pipe is lower than the engine bay
As stated above, the mode of heat transfer (hot always goes to cold) in this case is:
1) convection through the engine compartment air
2) conduction through the intercooler pipe material (think of this as our resistor)
3) convection to the air inside the pipes
Stainless steel has more resistance and will transfer heat slower over aluminum. Therefore, SS will transfer heat at a slower rate to the air passing through it. From a heat transfer perspective, SS would be the better material choice.
Now will how much difference this will make on our cars? I’m not sure if there would be a difference that’s noticeable. The only way to find out is to run an experiment!
These are the assumptions for this scenario:
- engine bay is warmed up and at steady state temperature
- temperature of air passing through the pipe is lower than the engine bay
As stated above, the mode of heat transfer (hot always goes to cold) in this case is:
1) convection through the engine compartment air
2) conduction through the intercooler pipe material (think of this as our resistor)
3) convection to the air inside the pipes
Stainless steel has more resistance and will transfer heat slower over aluminum. Therefore, SS will transfer heat at a slower rate to the air passing through it. From a heat transfer perspective, SS would be the better material choice.
Now will how much difference this will make on our cars? I’m not sure if there would be a difference that’s noticeable. The only way to find out is to run an experiment!
Oh yeah, thinner piping will also reduce the conduction through the piping as well as present a slightly smaller outside surface for convection, thus further reducing heat transfer from the engine bay air to the cooler charge air.
Originally Posted by Fenris Ulf
Oh yeah, thinner piping will also reduce the conduction through the piping as well as present a slightly smaller outside surface for convection, thus further reducing heat transfer from the engine bay air to the cooler charge air.
Originally Posted by marksae
Wouldn't you want thicker tubing? You're trying to stop heat from transferring from the engine bay through the pipe, so you'd want more conductive resistance right?