More effective Intercooler
11-13-2008, 09:16 AM
#11
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Originally Posted by blackey,Nov 13 2008, 02:09 PM
Seems like a lot of people here are guessing and are stating what they think, but really have no evidence or engineering behind it? If you think the a2w system is better show me how much air is needed to cool the water using math please.
I have tested both on a racetrack. The stock Vortech aftercooler vs the Ultimate Racing Intercooler. The Vortech system heatsoaked on the first lap and ran consistant temps of ambient + 90F. (Not good)
The Ultimate Racing intercooler was ambient + 3F. It was actually running cooler than the underhood temps where I was pulling air from.
If you calculate the energy it takes to pull heat out of water using air, it is staggering. The water is very efficient at pulling heat out of the air. Basically to pull the heat out of the water you reverse the process. Which inverts the equation. For drag racing the air to water is perfect. You can cool the air to less than ambient using dry ice. If you've ever seen how much ice it can use up you would be alarmed.
For street driving, most of the time the air to water is ok. For a canyon road drive the Air to Air will be better. For tracking, the air to air is definitely better.
Now it sounds to me the SOT kit has used a very high quality a2w system and a huge extra radiator to combat the problem. I've talked to Mark and they have the temps under control. The Vortech and Comptech kits, not so much.
A2W can be made to work, but is more complex and is more difficult to get right. There are more parts to fail, and those failures can be costly. The pluses are very little pressure drop, and you can mount the radiator anywhere, although I have yet to see anyone mount it any other place than in front of the radiator in the s2k.
The downside of air to air is the pressure drop. Figure a well designed A2A will have about 1psi more pressure drop than the A2W system. Not a problem with turbos, but something to consider with superchargers that are already at their RPM limit.
I have tested both on a racetrack. The stock Vortech aftercooler vs the Ultimate Racing Intercooler. The Vortech system heatsoaked on the first lap and ran consistant temps of ambient + 90F. (Not good)
The Ultimate Racing intercooler was ambient + 3F. It was actually running cooler than the underhood temps where I was pulling air from.
If you calculate the energy it takes to pull heat out of water using air, it is staggering. The water is very efficient at pulling heat out of the air. Basically to pull the heat out of the water you reverse the process. Which inverts the equation. For drag racing the air to water is perfect. You can cool the air to less than ambient using dry ice. If you've ever seen how much ice it can use up you would be alarmed.
For street driving, most of the time the air to water is ok. For a canyon road drive the Air to Air will be better. For tracking, the air to air is definitely better.
Now it sounds to me the SOT kit has used a very high quality a2w system and a huge extra radiator to combat the problem. I've talked to Mark and they have the temps under control. The Vortech and Comptech kits, not so much.
A2W can be made to work, but is more complex and is more difficult to get right. There are more parts to fail, and those failures can be costly. The pluses are very little pressure drop, and you can mount the radiator anywhere, although I have yet to see anyone mount it any other place than in front of the radiator in the s2k.
The downside of air to air is the pressure drop. Figure a well designed A2A will have about 1psi more pressure drop than the A2W system. Not a problem with turbos, but something to consider with superchargers that are already at their RPM limit.
You are right though... water does an amazing job of absorbing heat, but that heat needs to be expelled to be reused again, and that's where the problem comes in.
For constant motion, I think A2A would be better and if you have a mister (water or NO2), then that would even help more.
Andre
11-14-2008, 10:55 PM
#13
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Originally Posted by blackey,Nov 13 2008, 12:09 PM
Seems like a lot of people here are guessing and are stating what they think, but really have no evidence or engineering behind it? If you think the a2w system is better show me how much air is needed to cool the water using math please.
The Ultimate Racing intercooler was ambient + 3F. It was actually running cooler than the underhood temps where I was pulling air from.
The Ultimate Racing intercooler was ambient + 3F. It was actually running cooler than the underhood temps where I was pulling air from.
I don't currently have enough data to calculate heat flow requirement for the exchangers. But seeing how the car's radiator (also a W2A exchanger) can get rid of the engine's entire heat of ignition load, and the supercharger's heat of compression load is probably a small fraction of that number, I deduce that a properly-sized front-mount W2A exchanger, fed by a water pump with sufficient flow rate, should handle the heat transfer.
Now, adding a second heat medium fluid, pump, and second heat exchanger does lower the overall intercooler system efficiency a few points and add complexity, new modes of failure, and dollars. Are those A2W/W2A costs worth it in exchange for the packaging convenience? Are the A2A costs of lowered boost pressure (and its HP), longer charge pipe path with more joints and couplers and potential boost leak points, and tougher install worth it? Pick your poison.
3 deg over ambient is great for the A2A cooler. Glad you like that solution. I don't understand your last quoted statement though. How's a FMIC pull air from underhood? You running the course in reverse w/o any cooling fans? Do you have an unusual cooler placement? In normal airflow situation, FMIC ahould be cooler than underhood air because the radiator is also adding heat to the air after the intercooler does.
11-15-2008, 10:12 AM
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This is a repost of an earlier thread...
To sum things up, it depends on the overall efficiency of the heat exchanger units (be they A2A or A2W)-design of the heat exchangers is everything. BTW, overall weight differences on these units is small and has very little influence.
To sum things up, it depends on the overall efficiency of the heat exchanger units (be they A2A or A2W)-design of the heat exchangers is everything. BTW, overall weight differences on these units is small and has very little influence.
11-15-2008, 10:45 AM
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lets assume your blower has a 2" connection for the charge pipe
your intercooler has 2.5"
and throttle body is 2.75" (67mm stock, right?)
any recommendations on what size piping to run, and where to step sizes?
your intercooler has 2.5"
and throttle body is 2.75" (67mm stock, right?)
any recommendations on what size piping to run, and where to step sizes?
11-15-2008, 11:11 AM
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If you were to increase piping size or the throttle body inlet size (to a certain extent) you could allow for greater air flow (depending on TB design, etc), this in turn could lower boost pressure and would have to be compensated for (by tuning and/or increasing the turbine speed) to give additional power.
You are still under full boost pressure at the intake manifold so no expansion occurs to allow cooling (if this is what you were thinking).
I believe that the shorter air path design afforded by the A2W design may allow for less chance of leaks and thus more reliable boost pressures. But, at the cost of somewhat more complexity and maintenance. The A2A requires a longer path and is therefore subject to the increased possibility of leaks, but is less complex and requires far less maintenance. Overall efficiency will be influenced mostly by the heat exchanger designs of each system (as a practical matter vs theoretical).
You are still under full boost pressure at the intake manifold so no expansion occurs to allow cooling (if this is what you were thinking).
I believe that the shorter air path design afforded by the A2W design may allow for less chance of leaks and thus more reliable boost pressures. But, at the cost of somewhat more complexity and maintenance. The A2A requires a longer path and is therefore subject to the increased possibility of leaks, but is less complex and requires far less maintenance. Overall efficiency will be influenced mostly by the heat exchanger designs of each system (as a practical matter vs theoretical).
02-22-2009, 06:28 PM
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[QUOTE=dsmforums]alot of people run water intercoolers on the street with no problems and love them.
from spearco's page:
There are diverse opinions about the advantage of air/liquid intercoolers versus air/air intercoolers in drag racing applications. Some say there is no advantage over air/air and they also say if there is an advantage it is offset by the added weight.
The real facts are that other than a small additional weight factor, a proper application of an air/liquid intercooler will increase power much more than enough to offset any additional weight and will always yield superior performance over an air/air unit. And, sometimes the additional weight is needed for ballast and this disadvantage is erased.
To understand why air/liquid intercoolers are superior for drag racing, consider that the cooling medium in an air/air intercooler is the ambient temperature of the outside air at any given time. If we have an engine running 30PSI boost pressure, depending on compressor efficiency, the discharge temperature will be approximately 400
from spearco's page:
There are diverse opinions about the advantage of air/liquid intercoolers versus air/air intercoolers in drag racing applications. Some say there is no advantage over air/air and they also say if there is an advantage it is offset by the added weight.
The real facts are that other than a small additional weight factor, a proper application of an air/liquid intercooler will increase power much more than enough to offset any additional weight and will always yield superior performance over an air/air unit. And, sometimes the additional weight is needed for ballast and this disadvantage is erased.
To understand why air/liquid intercoolers are superior for drag racing, consider that the cooling medium in an air/air intercooler is the ambient temperature of the outside air at any given time. If we have an engine running 30PSI boost pressure, depending on compressor efficiency, the discharge temperature will be approximately 400
02-22-2009, 08:20 PM
#20
Originally Posted by 8kGoodENuff,Nov 12 2008, 03:34 PM
I know Mercedes Benz is smart and they use refrigerant to cool off the compressed air... now that's bada$$.