discussion about how intercoolers work
Mar 22, 2007, 12:45 PM
#1
discussion about how intercoolers work
http://www.niseiengineering.com/tutorials.html for preinformation before you read this.
for those of you that don't frequent evom you won't know that i've had a long drawn out conversation with many people about intercoolers, design, function and performance. that said...
an intercooler does two things and as such has two end goals.
the first end goal is the increase of horsepower and this end goal is achieved by both the intercooler's functions. you can increase the horsepower of the car by 1) increasing the air flow through the intercooler and 2) decreasing the temperature and hence knock threashhold and increase the ability to tune more hp out of the car.
the second end goal is directly related to the latter part of the first end goal, and that is to make the car run more safely, this is done through cooling the air and raising the knock threshold from whence you may tune more horsepower out of it.
are intercoolers a waste of money? simply put, no.
why? because they provide some of the best performance gains possible on your car. do i mean umpteenmillion horsepower? no. do i mean to tell you what amount of money justifies the intercooler's purchase? no. that is all up for you to decide. if you can't afford $2000 intercooler, then don't... will you get the $2000 intercooler's benefits? prolly not.
now you're all interested in what i run... i run a nisei. and this choice is well thought out (yes i'm on the stock turbo, enjoy yoself)
onto why you may need the intercooler on a stock turbo.
the stock turbo is a dinkie unit by world standards, it's a small compressor with a small turbine side and it's finely driven by a 2 liter engine. with that said... small turbos will heat up the air more than a larger turbo. larger turbos are more efficient, there is almost no exception to this rule and if there are i will point out why there are such exceptions. that said, an intercooler does what? let's refer back to end goal two and see that the second end goal of an intercooler is to reduce intake temperatures (this of course directly affects horsepower).
so you see in the end you end up "needing" an intercooler more for a small hot turbo than for a big cold turbo. so why do some SEEMINGLY uninformed people always say you "need" an intercooler for a big turbo, well it's because they're RIGHT TOO. if you recall end goal number one the former part it states that one way to increase horsepower is to increase flow through the intercooler. a larger intercooler will produce more overall flow capacity and will therefore produce the dyno numbers.
that said you can't have all or nothing, you can't have all flow with no cooling as that will not make you any hp. a 2.5" straight pipe will flow 2000hp or more, but you won't get 2000 horsepower out of it... cuz your engine will be knocking so bad that it breaks.
you also can't have all cooling, cuz in this universe you don't get anything for nothing. there are several ways to cool air but you can't cool it at ultimate efficiency and also retain ultimate flow characteristics. (more on this later).
and about heat soak think about quilibrium temperature. if you have an intercooler that cools air with a certain amount of effectiveness it's equilibrium operating temperature and hence your intake temperature will be lower than that of an intercooler that is less efficient. that said you need to think hard and beat out the details of what makes an intercooler more efficient and you can read the more-on-this-later-section.
so what does that learn you? i'm the real rick james *****... enjoy yoself.
now about how intercoolers work by design:
two categories we've all heard beaten to death, tube fin and bar plate.
bar plate is more massive, more sturdy will heat soak later. tube header is lighter more delicate and has some manufacturing quirks, mainly that the tube and header assembly must be fused together, this needs to be done with either a certain amount of precision or a certain amount of tolerance such that the intercooler is not holey when it comes out.
what would i pick for the ultimate intercooler tube fin cuz it's lighter. what do i own? bar plate cuz it's better. if that confuses you... don't worry about it and you can send me a pm to help you make a personal decision.
with that said let's move on to fin design.
fin design is the most important part of the intercooler and directly dictates the intercooler's cooling capabilities.
typical fin designs and their related intercoolers.
lobe design is featured IN the greddy vspec
louvred fin design is featured IN the greddy rspec (also on the outside), arc evo spec, many garrett cores, many spearco cores
straight fused fin design is featured on the outside of the arc core, outside of many garrett cores, the outside of many spearco cores and other cores that may use sourced cores such as turboxs (inside and out) xs engineering (outside for sure never seen inside).
nisei uses a proprietary "split" fin design inside and out, the avo intercooler also uses a split fin design on the inside.
hks has a proprietary and ****ty system of hybrid lobe and louvred fin cores. more on this later (mainly why it's ****ty).
now on to the benefits and detractors of each design.
lobe is by far the worst design for cooling and as such is the best design for air flow. a lobe type core is only used in tube fin intercoolers and if you look down the tube you will see bumps that run parallel with the tube, all the way down. these bumps only increase the surface area and hence the conduction area by the amount that the perimeter of the tube increases.
straight fin is a little better, the fins are fused to each side of the internal tubes (bar or tube) and as such increase the surface areay by the amount length of the sheet metal (which is compressed like an accordian) times two (for both sides of the sheet) minus the fuse points. this is quite an increase indeed, and the flow is relatively undisturbed as it just turns the transfer tube into a bunch of smaller transfer tubes.
a louvred fin is the same as a straight fin but it has cuts in it and as such the fins seperate out with a sort of leaf shape. this said the louvres are there to slow down air so the air has more time to transfer heat to the transfer tubes. slower air means less air flow capacity.
the split fin design is not one piece of sheet metal made into an accordian but many pieces of sheet metal bent into a long U shapt individually fused to the cooling bars. these are then cut and split so that the air snakes its way through the core.
hks has a cute marketing ploy where they try to make the ultimate cooler that flows and cools without much pressure drop. since you're not so good at measuring the cooling part what they did was made a gigantic cooler made half of it lobe, which passes the air right through, made half of it louvred so some of the air gets cooled and then tried to pass that off to you as a great design. i'm obviously not a fan.
now some considerations.
you are wondering what a transfer tube is... the transfer tube is what the air INSIDE goes through. the cooling tube is the tube that actually does the cooling and it is attatched to the transfer tube. basically the cooling tubes are the long rows of fins you see on the outside which then actually get the heat taken away from them.
some people like xs engineering claim that radiator air flow is important and you shouldn't block it with small cooling tubes that have dense finning so they put straight fins on their cooling tubes
also most of the time there is a specific ratio of cooling to transfer tube heights. there should usually be more cooling tube than transfer tube. with that said the nisei sports dense *** fins on the outside and sports a 1:1 ratio for their tube heights.
another consideration is the more fins you put inside of an intercooler the less space you have to fill with air. this affects boost up. however the more dense a core is the more restrictions are in place so only so much can be got from this.
now for discussion on the ultimate intercoolers. if i had all the money in the world i would probably have an arc intercooler. mostly because if i broke it i could get another one. does it cool as well as the nisei? no. but it's lighter. and weight is priceless. you can always make more horsepower but you can only lose so much weight before you flintstone it around the track.
why arc? because of the quality, when buying tube fin quality is hte ultimate concern. arc's cores are made so meticulously that if you look into one you'll see every fin is fused to perfection. every weld is spot on (that means no leaks) every tube fused with the header has the LEAST mount of header protrusion and i believe they even have velocity stacks for the parts that are protruding. that said this intercooler is a bargain for the quality you get. cuz i don't know how they can make something so high class even with modern machinery.
why do i have the nisei? cuz i live in southern california where the temps are ridiculous. racing in the desert requires ultimate cooling not ultimate weight reduction. race don't mean **** if you can't finish it. believe you me... it does not get any better than the nisei intercooler. BAR NONE. period. and i say this from a very educated and researched standpoint.
for those of you that don't frequent evom you won't know that i've had a long drawn out conversation with many people about intercoolers, design, function and performance. that said...
an intercooler does two things and as such has two end goals.
the first end goal is the increase of horsepower and this end goal is achieved by both the intercooler's functions. you can increase the horsepower of the car by 1) increasing the air flow through the intercooler and 2) decreasing the temperature and hence knock threashhold and increase the ability to tune more hp out of the car.
the second end goal is directly related to the latter part of the first end goal, and that is to make the car run more safely, this is done through cooling the air and raising the knock threshold from whence you may tune more horsepower out of it.
are intercoolers a waste of money? simply put, no.
why? because they provide some of the best performance gains possible on your car. do i mean umpteenmillion horsepower? no. do i mean to tell you what amount of money justifies the intercooler's purchase? no. that is all up for you to decide. if you can't afford $2000 intercooler, then don't... will you get the $2000 intercooler's benefits? prolly not.
now you're all interested in what i run... i run a nisei. and this choice is well thought out (yes i'm on the stock turbo, enjoy yoself)
onto why you may need the intercooler on a stock turbo.
the stock turbo is a dinkie unit by world standards, it's a small compressor with a small turbine side and it's finely driven by a 2 liter engine. with that said... small turbos will heat up the air more than a larger turbo. larger turbos are more efficient, there is almost no exception to this rule and if there are i will point out why there are such exceptions. that said, an intercooler does what? let's refer back to end goal two and see that the second end goal of an intercooler is to reduce intake temperatures (this of course directly affects horsepower).
so you see in the end you end up "needing" an intercooler more for a small hot turbo than for a big cold turbo. so why do some SEEMINGLY uninformed people always say you "need" an intercooler for a big turbo, well it's because they're RIGHT TOO. if you recall end goal number one the former part it states that one way to increase horsepower is to increase flow through the intercooler. a larger intercooler will produce more overall flow capacity and will therefore produce the dyno numbers.
that said you can't have all or nothing, you can't have all flow with no cooling as that will not make you any hp. a 2.5" straight pipe will flow 2000hp or more, but you won't get 2000 horsepower out of it... cuz your engine will be knocking so bad that it breaks.
you also can't have all cooling, cuz in this universe you don't get anything for nothing. there are several ways to cool air but you can't cool it at ultimate efficiency and also retain ultimate flow characteristics. (more on this later).
and about heat soak think about quilibrium temperature. if you have an intercooler that cools air with a certain amount of effectiveness it's equilibrium operating temperature and hence your intake temperature will be lower than that of an intercooler that is less efficient. that said you need to think hard and beat out the details of what makes an intercooler more efficient and you can read the more-on-this-later-section.
so what does that learn you? i'm the real rick james *****... enjoy yoself.
now about how intercoolers work by design:
two categories we've all heard beaten to death, tube fin and bar plate.
bar plate is more massive, more sturdy will heat soak later. tube header is lighter more delicate and has some manufacturing quirks, mainly that the tube and header assembly must be fused together, this needs to be done with either a certain amount of precision or a certain amount of tolerance such that the intercooler is not holey when it comes out.
what would i pick for the ultimate intercooler tube fin cuz it's lighter. what do i own? bar plate cuz it's better. if that confuses you... don't worry about it and you can send me a pm to help you make a personal decision.
with that said let's move on to fin design.
fin design is the most important part of the intercooler and directly dictates the intercooler's cooling capabilities.
typical fin designs and their related intercoolers.
lobe design is featured IN the greddy vspec
louvred fin design is featured IN the greddy rspec (also on the outside), arc evo spec, many garrett cores, many spearco cores
straight fused fin design is featured on the outside of the arc core, outside of many garrett cores, the outside of many spearco cores and other cores that may use sourced cores such as turboxs (inside and out) xs engineering (outside for sure never seen inside).
nisei uses a proprietary "split" fin design inside and out, the avo intercooler also uses a split fin design on the inside.
hks has a proprietary and ****ty system of hybrid lobe and louvred fin cores. more on this later (mainly why it's ****ty).
now on to the benefits and detractors of each design.
lobe is by far the worst design for cooling and as such is the best design for air flow. a lobe type core is only used in tube fin intercoolers and if you look down the tube you will see bumps that run parallel with the tube, all the way down. these bumps only increase the surface area and hence the conduction area by the amount that the perimeter of the tube increases.
straight fin is a little better, the fins are fused to each side of the internal tubes (bar or tube) and as such increase the surface areay by the amount length of the sheet metal (which is compressed like an accordian) times two (for both sides of the sheet) minus the fuse points. this is quite an increase indeed, and the flow is relatively undisturbed as it just turns the transfer tube into a bunch of smaller transfer tubes.
a louvred fin is the same as a straight fin but it has cuts in it and as such the fins seperate out with a sort of leaf shape. this said the louvres are there to slow down air so the air has more time to transfer heat to the transfer tubes. slower air means less air flow capacity.
the split fin design is not one piece of sheet metal made into an accordian but many pieces of sheet metal bent into a long U shapt individually fused to the cooling bars. these are then cut and split so that the air snakes its way through the core.
hks has a cute marketing ploy where they try to make the ultimate cooler that flows and cools without much pressure drop. since you're not so good at measuring the cooling part what they did was made a gigantic cooler made half of it lobe, which passes the air right through, made half of it louvred so some of the air gets cooled and then tried to pass that off to you as a great design. i'm obviously not a fan.
now some considerations.
you are wondering what a transfer tube is... the transfer tube is what the air INSIDE goes through. the cooling tube is the tube that actually does the cooling and it is attatched to the transfer tube. basically the cooling tubes are the long rows of fins you see on the outside which then actually get the heat taken away from them.
some people like xs engineering claim that radiator air flow is important and you shouldn't block it with small cooling tubes that have dense finning so they put straight fins on their cooling tubes
also most of the time there is a specific ratio of cooling to transfer tube heights. there should usually be more cooling tube than transfer tube. with that said the nisei sports dense *** fins on the outside and sports a 1:1 ratio for their tube heights.
another consideration is the more fins you put inside of an intercooler the less space you have to fill with air. this affects boost up. however the more dense a core is the more restrictions are in place so only so much can be got from this.
now for discussion on the ultimate intercoolers. if i had all the money in the world i would probably have an arc intercooler. mostly because if i broke it i could get another one. does it cool as well as the nisei? no. but it's lighter. and weight is priceless. you can always make more horsepower but you can only lose so much weight before you flintstone it around the track.
why arc? because of the quality, when buying tube fin quality is hte ultimate concern. arc's cores are made so meticulously that if you look into one you'll see every fin is fused to perfection. every weld is spot on (that means no leaks) every tube fused with the header has the LEAST mount of header protrusion and i believe they even have velocity stacks for the parts that are protruding. that said this intercooler is a bargain for the quality you get. cuz i don't know how they can make something so high class even with modern machinery.
why do i have the nisei? cuz i live in southern california where the temps are ridiculous. racing in the desert requires ultimate cooling not ultimate weight reduction. race don't mean **** if you can't finish it. believe you me... it does not get any better than the nisei intercooler. BAR NONE. period. and i say this from a very educated and researched standpoint.
Mar 22, 2007, 01:13 PM
#2
You were really bored weren't you 
I'll give my abridged version with some key points and none of the technical stuff.
There are 2 main areas of interest in IC design (as with any heat exchanger): heat transfer capacity and pressure drop. These two things apply to the air from the turbo going through the IC and the outside air going through the IC.
Better heat transfer capacity (through fin design, more fins, etc), the greater the pressure drop. For drag racing, bar and plate is great because it has getter heat transfer, but it also has more flow resistance of the outside air going through it, which reduces the airflow going to your radiator. Plus, this air is hotter.
So for road course work, I'd go tube and fin. But anyways, it's all a balance between cooling efficiency and pressure drop.
I'll give my abridged version with some key points and none of the technical stuff.
There are 2 main areas of interest in IC design (as with any heat exchanger): heat transfer capacity and pressure drop. These two things apply to the air from the turbo going through the IC and the outside air going through the IC.
Better heat transfer capacity (through fin design, more fins, etc), the greater the pressure drop. For drag racing, bar and plate is great because it has getter heat transfer, but it also has more flow resistance of the outside air going through it, which reduces the airflow going to your radiator. Plus, this air is hotter.
So for road course work, I'd go tube and fin. But anyways, it's all a balance between cooling efficiency and pressure drop.
Mar 22, 2007, 11:21 PM
#4
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Excellent discussion trinydex. I have been interested into buying a Nisei intercooler way before doing any research about it (pretty dumb on my part) but now I know for sure that i'm making the right choice 
. I also wish i had the money for an ARC intercooler , maybe one of these days.
Finally, which design are for the Buschur and/or AMS intercoolers? Are they the real shiznit or not?
. I also wish i had the money for an ARC intercooler , maybe one of these days.Finally, which design are for the Buschur and/or AMS intercoolers? Are they the real shiznit or not?
Mar 23, 2007, 07:30 AM
#6
hmmm... looks like nisei is scrambling out the fanboy's. i'll wait for 94awdcoupe to run his test before i make my purchase decision. we'll soon find out who blows hot air.
Mar 23, 2007, 07:40 AM
#7
Damn! Damn right, he must have been bored.
As far as Proprietary fin designs and such, there are core manufacturing companies out there that will produce any design you wish.
We actually had two different cores for the upgraded SRT-4 units. One had 1/4" charge tubes (for use with the stock turbo) and the other had 3/8" charge tubes (for upgraded turbos) The IC with the 3/8" tubes flowed more air but dissipated less heat. the 1/4" was the opposite.
As far as Proprietary fin designs and such, there are core manufacturing companies out there that will produce any design you wish.
We actually had two different cores for the upgraded SRT-4 units. One had 1/4" charge tubes (for use with the stock turbo) and the other had 3/8" charge tubes (for upgraded turbos) The IC with the 3/8" tubes flowed more air but dissipated less heat. the 1/4" was the opposite.
Trending Topics
Mar 23, 2007, 07:44 AM
#8
funny thing is,
the 12 hour endurance cars i raced... aka LMP cars... turbocharged... the ones that run at the lemans 24 hours
used tube/fin ics.
we are now using some PWR cores... alittle more flow through the rad is a good thing.
cb
the 12 hour endurance cars i raced... aka LMP cars... turbocharged... the ones that run at the lemans 24 hours
used tube/fin ics.
we are now using some PWR cores... alittle more flow through the rad is a good thing.
cb
Last edited by CBRD; Mar 23, 2007 at 08:03 AM.
Mar 23, 2007, 09:45 AM
#10
You were really bored weren't you
I'll give my abridged version with some key points and none of the technical stuff.
There are 2 main areas of interest in IC design (as with any heat exchanger): heat transfer capacity and pressure drop. These two things apply to the air from the turbo going through the IC and the outside air going through the IC.
Better heat transfer capacity (through fin design, more fins, etc), the greater the pressure drop. For drag racing, bar and plate is great because it has getter heat transfer, but it also has more flow resistance of the outside air going through it, which reduces the airflow going to your radiator. Plus, this air is hotter.
So for road course work, I'd go tube and fin. But anyways, it's all a balance between cooling efficiency and pressure drop.
I'll give my abridged version with some key points and none of the technical stuff.
There are 2 main areas of interest in IC design (as with any heat exchanger): heat transfer capacity and pressure drop. These two things apply to the air from the turbo going through the IC and the outside air going through the IC.
Better heat transfer capacity (through fin design, more fins, etc), the greater the pressure drop. For drag racing, bar and plate is great because it has getter heat transfer, but it also has more flow resistance of the outside air going through it, which reduces the airflow going to your radiator. Plus, this air is hotter.
So for road course work, I'd go tube and fin. But anyways, it's all a balance between cooling efficiency and pressure drop.
https://www.evolutionm.net/forums/sh...d.php?t=259412
Last edited by trinydex; Mar 23, 2007 at 09:54 AM.
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