I managed to get through the whole article in that link...
Couple things that worry me:
1) It made my head hurt to read that whole thing. I realize that they are in Aussie / Down Under, but is the English really that bad? I would figure if they want to sound like an authority, the article should be revised a few more times.

2) They guy works for a business. I can smell the commercial bias in there - or is it just me? The part about them recommended extruded cores scares me.

Almost everything else has already been covered by Maximum Boost by Corky Bell.


-Ted

 

theres 2 things a better end tank design can get you.

1. better total flow, if you make it better it should flow a little more. this is a small consideration, i think most of the intercoolers that fit in these cars arent a restriction.

2. better distribution of air. if the end tank is really bad most of the air is gonna flow thru a smaller number of tubes, so some will be hotter than others, or some of the intercooler isnt working as hard as it could be. if you distribute this air better, then the whole core is going to work better, and thus can be made smaller, or kept big and you can lower your intake temps a little more.

2b. if you're improving the air flow in the intercooler, why not optimise the air flow ON the cooler too, if the hood latch is in the way, that bit of cooler isnt working as well as it could. granted its nice to have a hood too....

real world examples:

we got to see an 80's imsa celica at laguna seca, and they had an interesting setup, intercooler and radiator were right next to each other, both on the smaller side maybe 16" W x 22" T x 3" deep, intercooler inlet went from a 2.5" pipe to a "fan" shape into the core.

paul had an intercooler made for his fc, i believe the core was 31" wide and 20ish tall, basically its the largest core that fits. it needs end tanks also in a fan shape because there was something like 1" of clearance on each side.

we're thinking now that water to air is an easier deal to package, as a giant intercooler helps the air temps, but we want low coolant and oil temps too, and all 3 seem hard to acomplish in a road racing fc with an air to air

 

I'm just worried about point 2, getting the flow even so I'm using the core effectively. If there is extra material I'm not using, why should I have it? I'm going to try and shroud the air extremely well into the front and make end tanks that at least have some effort to use all of the core. I'm just debating whether I should run something like a 4"+ thick core that is really short and long so something more like 7x4x30 instead of a 10x3x20 or something like that

 

My impression is that you would want the thinner core section as it improves total airflow through the core, which is usually the limiting factor in air to air exchange (assuming there is enough surface area on the inside of the core; ideally inside vs. out should be about 1:1). Additionally, the differential temperature is reduced toward the back of thicker cores reducing the rate of [heat] rejection. At some point in core thickness, you will hit a point of diminishing returns--as you slow the air down and heat it up.

It will be more difficult to control distribution inside a core that has very low impedance to airflow (boost side). An example would be many short rows vs. fewer but longer core rows. Some resisitance in the core will help with this as will an intellegently designed transition into the core. Note that a proper flow "distributor" will have a exponential like curve to it and NOT be linear. (We are trying to keep the same constant pressure above each tube inlet). However, some sort of conical section or taper is probably better than none at all, and in practice, if the tank is very large, it can function as a plenum and work pretty well from a distribution standpoint, but the excess volume is not helpful for other reasons.

Am I making any sense here or did I just convolute the matter even more???

 

since its in front of the radiator, you want a thinner, but larger in height and width core. radiator needs air flow too....

 

I just want to add to the conversation without contradicting anyone else, as most are really good points. I too am an engineer, although im a chemical engineer, i have done a lot of work with heat transfer, fluids, and thermodynamics. One more point that a lot of people havent really mentioned is that, you intercoolers size and efficiency should also be determined based on the size and efficiency of their turbo not by how much hp you want to make. Typically larger turbos require less boost and thus less cooling. Also smaller turbos at the same boost level as the bigger turbos also create more heat and thus require more cooling. So if your running a turbo that only requires say 20 psi to create the desired 500 whp vs a turbo that requires say 28 psi for the desired hp, you can actually get away with a smaller or less efficient intercooler.

now onto end tanks and intercooler efficiency. I have some recent real world experience with a change in intercooler. I have recently switched from a apexi core intercooler with, what in my mind was a terrible end tank design with smaller end tank piping to a Trust/Greddy 3 row unit with what is in my mind a much better design. Although the new core is about 1 inch thicker than the old one, the new one is also almost half the width as the old core. After switching intercooler i went out for a tuning session and noticed that my old tune at 25 psi which i had tuned to 10.6 to 1, is had now went into the low 12s to 1. Thank god we had race gas in it, and let off the car in time, because i probably would have blown my motor. So because i switched to a more efficient end tank design (even with an overall smaller core), i now force a substantial amount of air more than my old setup, at the same amount of boost. This obviously equals more power Not only this, but now my water temps stay much lower, due to more air flow to the radiator.

Adam

 

oh btw, my old intercooler was bar and plate, and the new one is tube and fin. I definately prefer tube and fin.

 

fastcarfreak You are correct. What you are really trying to do is size the intercooler for the proper [air] density recovery. To do this correctly, you need to know the turbo's pressure ratio at max boost, efficiency at that PR, and, of course engine displacement and RPM.

Your experience with the I/C illustrates the benifits of improved density recovery. Your new intercooler is apparently more efficient at heat rejection and/or has better distribution & less total pressure drop. My own impression is that tube & fin designs seem to have more internal surface area, which is beneficial.

You should now be able to make the same power with less absolute boost pressure. And less stress on all the components: engine, turbos, etc..

 

now why would i want to do that when i can benifit from more power at the same boost level

 

Although all of the above is NICE to know , I'm sure your question remains.... , apart from the guy who said to use the NPR , nothing else was specific. I have been there and I got confused too , what I suggest doing is first deciding how much money you have to spend , how much space you have to work with and do a search to find cars making the power you want and just go ahead and get what they use , also remember that you should think of the radiator too , I have some friends who went with MASIVE core intercoolers , up to 6 " thick , but couldnt drive more than ten minutes without over heating . I ended up going with the large NPR , I saw this on Mr Gonzalezs' RX2 race car , he was making well over 500 RWHP with it , I also decided to go a little further and put together a great water injection system for even better cooling and detonation resistance , instead of spending the extra cash for one of those Huge name brand ones that can NOT drop temps lower than ambient, with water injection and my intercoler , I see 2 degrees above ambient @ 15psi boost !
This is the tread , Im not seeing all the pics anymore , but the NPR is mentioned.
https://www.rx7club.com/showthread.p...arlos+Gonzalez

 

I also am an advocate for water/meth injection and rotary engines. I think the only reason i didnt blow at 25 psi and the over 12:1 afr is because of it. It just had some really healthy surging.