fans on the intercooler?
09-07-2004, 11:08 PM
#31
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Originally Posted by Mister 2
Nope, I didn't misread. You're saying that pressure will be equalized on the surface of the intercooler and I don't see how you can jump to that conclusion w/out either experimental or computational data. Take your bucket idea and instead of putting holes in the bottom, replace the bottom of the bucket w/ a screen and then shoot water onto just the backhalf of the bucket.
And yes, i agree that there is more flow restriction thru an IC so using a screen is one extreme but my argument is that making holes w/ an ice pick is the other extreme. I've seen enough experimental and computation fluid dynamics to know that more needs to be known before you can make the conclusions you've made.
And yes, i agree that there is more flow restriction thru an IC so using a screen is one extreme but my argument is that making holes w/ an ice pick is the other extreme. I've seen enough experimental and computation fluid dynamics to know that more needs to be known before you can make the conclusions you've made.
Oh, and to Ride5000 -- this is a great point, but you picked an uneven comparison. A radiator and an intercooler are extremely different in their jobs and function, and in how and what they actually cool (as I'm sure you're aware). Out of curiosity, I looked up the size of a common radiator fan, and it won't fit under a standard WRX hood scoop; perhaps an STI scoop. They also come in pairs, so you'd have to do some work with a sawz-all.
I don't have some sort of mission to rain on anyone's parade about this fans on the intercooler idea; it just seems like an overengineered and inefficient design compared to the practical, usable technologies (water spray, C02 spray, FMIC) that already exist and are off-the-shelf products. Trust me, living in Arizona I would jump at any magic solution to heat soak!
09-07-2004, 11:49 PM
#32
Originally Posted by gdogg
forgive me for not reading everyones posts...
my simplistic yet barbaric approach is this. coolings fans are great. at a standstill.
ever wonder why radiator fans are on the back side of the radiator?
unless you're planning on sitting at a traffic light for extended periods of time i see no positive value of cooling fans on a IC.
aloha from the summit of Mauna Kea
my simplistic yet barbaric approach is this. coolings fans are great. at a standstill.
ever wonder why radiator fans are on the back side of the radiator?
unless you're planning on sitting at a traffic light for extended periods of time i see no positive value of cooling fans on a IC.
aloha from the summit of Mauna Kea
-- Ed
09-08-2004, 05:57 AM
#33
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well, i've got my two spal fans in hand--they arrived friday.
next i am putting together the electrical control system. i have ordered two N/O thermostats from mouser electronics, one set for 100F, the other for 170F. i will first try mounting one of them right to the turbo heatshield. the heatshield does not get cooled directly by the fans, but it is by far the largest contributor to the heatsoak issue. if the heatshield gets hot, you can be sure your TMIC is going to get hot soon too. if the heatshield is cool, then there really isn't much of a chance that the IC will become hot. if the car is stopped and the engine radiator fans kick on, temps are already on the rise and i would assume that the heatshield will be heating up simultaneously, or within a few minutes. this is important and will have to be tested in situ as i do not want the radiator fans pumping hot air out through the hoodscoop. the IC fans are intended to combat this.
c'mon folks--do you really think that the side that the fans are on makes a damned bit of difference? air in = air out, restriction on intake = restriction on output.
ban suvs: guys set up to drag race by and large do not use TMICs.
tell me how the manner in which they cool is drastically different. both are passive heat transfer devices--for most intents and purposes, fluid to fluid. both transfer heat energy from inside the core to the oustide. both have temperature differentials that are between 60 and 120 degrees farenheit. don't you think it's just a bit strange that a FMIC will necessarily have the radiator fans present and pulling air through it when the car is at rest?
also consider an air-water intercooler like stealth-wrx has made himself. the only thing different in his case is that he has a fluid intermediate heat transfer medium instead of just metallic IC core.
in other words, you've failed miserably in convincing me of your point.
the fans will go on the top of the ic. i have already powered them up and to compare real automotive cooling fans to the fans off of a computer is a complete joke. there is absolutely no doubt in my mind that once the fans are installed and wired up i will never have to worry about heatsoak again.
http://ken-gilbert.com/wrx/6fans.pdf
ken
next i am putting together the electrical control system. i have ordered two N/O thermostats from mouser electronics, one set for 100F, the other for 170F. i will first try mounting one of them right to the turbo heatshield. the heatshield does not get cooled directly by the fans, but it is by far the largest contributor to the heatsoak issue. if the heatshield gets hot, you can be sure your TMIC is going to get hot soon too. if the heatshield is cool, then there really isn't much of a chance that the IC will become hot. if the car is stopped and the engine radiator fans kick on, temps are already on the rise and i would assume that the heatshield will be heating up simultaneously, or within a few minutes. this is important and will have to be tested in situ as i do not want the radiator fans pumping hot air out through the hoodscoop. the IC fans are intended to combat this.
c'mon folks--do you really think that the side that the fans are on makes a damned bit of difference? air in = air out, restriction on intake = restriction on output.
ban suvs: guys set up to drag race by and large do not use TMICs.
A radiator and an intercooler are extremely different in their jobs and function, and in how and what they actually cool (as I'm sure you're aware).
also consider an air-water intercooler like stealth-wrx has made himself. the only thing different in his case is that he has a fluid intermediate heat transfer medium instead of just metallic IC core.
in other words, you've failed miserably in convincing me of your point.
the fans will go on the top of the ic. i have already powered them up and to compare real automotive cooling fans to the fans off of a computer is a complete joke. there is absolutely no doubt in my mind that once the fans are installed and wired up i will never have to worry about heatsoak again.
http://ken-gilbert.com/wrx/6fans.pdf
ken
09-08-2004, 07:44 AM
#34
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Originally Posted by meilers
You still aren't applying the ideas behind the analogy. If there is enough water to cover the bottom of the bucket entirely, you will get equalized pressure out of all the holes. New water entering the bucket will add mass and pressure to the existing water, and it will be forced out of all holes equally. If the water is indeed hitting only one side of the bucket, it will definitely flow out of the holes on that side unequally -- that is the operation of the intercooler *under insufficient pressure*. Once the scoop is pressurized with air (i.e. once the bucket is FULL) then the flow is equal through all points of gradient from high to low pressure. Again, don't take my word for it, go out in the backyard and try it. Note that the experiment only works if the bucket is level, as gravity has a much stronger influence on the more massive water than it does air.
I was simply pointing out the weakness in your analogy. The screen bottom does not provide enough of a dp (read "pressure differential") to equalize pressure across it. That is my point.
Have you gone out into your backyard with the bucket w/ the screen bottom yet? I doubt you will so I'll try to make this more clear.
You say:
"If there is enough water to cover the bottom of the bucket entirely, you will get equalized pressure out of all the holes."
I totally agree but the key word there is "If".
You also say:
"Once the scoop is pressurized with air (i.e. once the bucket is FULL) then the flow is equal through all points of gradient from high to low pressure."
My question is at what point is the scoop pressurized (15 mph, more?)? Well it all depends on the dp thru the intercooler core. If there is a realatively low dp across the core then the air will pass thru easily without equalizing across the top of the IC (like a screen at the bottom of the bucket).
So meilers, going back to your bucket analogy. How many holes on the bottom would be representative of an IC and how much flow should I be putting into it (i.e. how fast is the car going)?
If I put thousands of holes in the bottom then it'll be just like a screen and the only way to equalize pressure across it is to flow water with a firehose. Otherwise I can just punch 2-3 holes in the bottom and then I can probably use a straw to fill the bucket.
I'll go and do the backyard experiment as soon as you answer that question AND explain to me how you know the answer to it.
edit: I don't mean to crap on you but I'd rather encourage (than discourage) Ride and his little experimentation. Coming from a MR-2 background which also has problems with the size and location of the intercooler. I've seen nice results using Spal fans.
Last edited by Mister 2; 09-08-2004 at 07:46 AM.
09-08-2004, 11:03 AM
#35
I think you guys are saying the same thing. The disagreement is weather or not there will be enough flow to equalize the pressure accross the IC core. I don't have any data on this, so I won't try to guess at a speed at which there is enough flow. So the point here is that a IC splitter will make a difference at low speeds and potentially cool down a heat-soaked IC quicker than just the plain scoop.
As far as placing the fan above or bellow the IC, I still think that a puller fan would be better suited for this. Fans on top of the IC will abstruct flow into the scoop and also change the fluid dynamics of the scoop/seal. On the bottom of the IC, we already have IC hoses that make some obstruction, and I doubt that a fan will add much more. Also, using your radiator analogy... pretty much all radiators I've seen use puller fans... think there's a reason for that?
-- Ed
As far as placing the fan above or bellow the IC, I still think that a puller fan would be better suited for this. Fans on top of the IC will abstruct flow into the scoop and also change the fluid dynamics of the scoop/seal. On the bottom of the IC, we already have IC hoses that make some obstruction, and I doubt that a fan will add much more. Also, using your radiator analogy... pretty much all radiators I've seen use puller fans... think there's a reason for that?
-- Ed
09-08-2004, 11:16 AM
#36
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Originally Posted by vaus
Also, using your radiator analogy... pretty much all radiators I've seen use puller fans... think there's a reason for that?
a push type fan creates an area of very high velocity and total cfm right behind the blades themselves.
the pull type, with a well-designed shroud, will create a more even flow distribution across the entire area, not just that covered by the fan blades themselves.
therefore more of the ic core is exposed to the flow of ambient air, and better efficiency results.
it's more efficient, but it CAN'T be less obstructive--that would be like saying a resistor's location in a current loop (wrt the load or power source) makes a difference in how it acts, or the voltage drop developed across it.
jm2c
ken
09-08-2004, 12:50 PM
#37
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Front mount suggestion
Or you could just solve the whole problem and get a front mounted intercooler. therefore you don't have to worry about the scoop and you get instant air
09-08-2004, 03:06 PM
#39
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For your reading pleasure, with photos and post-IC intake temp data to back it up.
http://forums.nasioc.com/forums/show...highlight=SPAL
I actually bought these two fans from Austin, but have yet to use them on a daily basis. I did hook up a plug to my cigarette lighter for use in the staging lanes at the drags, just for peace of mind, but I'm needing something to control the fans according to MPH.
http://forums.nasioc.com/forums/show...highlight=SPAL
I actually bought these two fans from Austin, but have yet to use them on a daily basis. I did hook up a plug to my cigarette lighter for use in the staging lanes at the drags, just for peace of mind, but I'm needing something to control the fans according to MPH.
09-08-2004, 04:49 PM
#40
Originally Posted by ride5000
that would be like saying a resistor's location in a current loop (wrt the load or power source) makes a difference in how it acts, or the voltage drop developed across it.
jm2c
ken
jm2c
ken
-- Ed
09-08-2004, 04:54 PM
#41
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Originally Posted by vaus
Also, the space bellow the IC is much more open than the pressurized scoop, -- Ed
09-09-2004, 04:32 AM
#42
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Originally Posted by vaus
Sorry, you can't compare air flow to voltage and current that simply. Its very far from the same thing and acts differently as well. I still say that a pull type will pose less of a restriction. The way I see it, the air is moving slower by the time it gets to the fan after passing through the intercooler, so the pressure drop across the fan is less than if it was above the IC. Also, the space bellow the IC is much more open than the pressurized scoop, so any restriction/turbulence there should be less significant to the overall flow. Honestly, I doubt the difference is large, but I'd still rather go for a pull type fan for daily use.
-- Ed
-- Ed
are you actually saying that the # of air molecules entering the top of the TMIC is different than the # of air molecules exiting the bottom? that the air MASS is somehow different? you have a closed system. air mass in MUST = air mass out.
do i agree that there are advantages to the pull type? absolutely. but i'm telling you that "less restriction" is not one of those.
as i see it, the most glaring problem with a pull type is a) need for an effective shroud (otherwise you have no advantage over a push type), and b) fitting it all underneath the IC core, particularly around the Y-pipe.
ken
09-09-2004, 10:05 AM
#44
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Originally Posted by wrx ish
people are still arguing about this?
09-09-2004, 10:30 AM
#45
Originally Posted by ride5000
i think you're way off base here, ed.
are you actually saying that the # of air molecules entering the top of the TMIC is different than the # of air molecules exiting the bottom? that the air MASS is somehow different? you have a closed system. air mass in MUST = air mass out.
do i agree that there are advantages to the pull type? absolutely. but i'm telling you that "less restriction" is not one of those.
as i see it, the most glaring problem with a pull type is a) need for an effective shroud (otherwise you have no advantage over a push type), and b) fitting it all underneath the IC core, particularly around the Y-pipe.
ken
are you actually saying that the # of air molecules entering the top of the TMIC is different than the # of air molecules exiting the bottom? that the air MASS is somehow different? you have a closed system. air mass in MUST = air mass out.
do i agree that there are advantages to the pull type? absolutely. but i'm telling you that "less restriction" is not one of those.
as i see it, the most glaring problem with a pull type is a) need for an effective shroud (otherwise you have no advantage over a push type), and b) fitting it all underneath the IC core, particularly around the Y-pipe.
ken
Its not really a closed system. Bellow the IC, there is no seal, shroud, or anything to direct the air flow. And no, I'm not saying that the # of air molecules entering the top of the IC is different that the # exiting the bottom. I am, however saying that there is significantly less pressure bellow the IC than above it (at speed), which is why the scoop/IC work in the first place. Since there is less pressure bellow the IC, the pressure drop accross the fan will be less than if it was on top of the IC, especially considering that the volume of air space bellow the IC isn't nearly as limited as it is above. Like I said, the difference probably isn't huge, but I still think there is a difference.
-- Ed