Intercooler characteristics
 

There are many shapes and build types of aftermarket intercoolers. Tube and fin, bar and plate, and the end tank configuration. Some coolers are long and thin with small endtanks at each end, while others are of simliar length but with the endtanks on the large (top & bottom) ends.

If the intercooler core is a restriction, it would act like electrical resistors: put them in series and the restriction increases, put them in tandem and the restriction is reduced (based on total core area or resistor ohm rating, respectively). A wide core entrance area (tank profile) with a short path through the core should pose less of a restriction than a small entrance area with a long path. I'm shooting for having a small pressure drop after the intercooler, coming from an Eaton M90, feeding a ported NA engine that is making roughly 160 rwhp at atmospheric pressure.

So . . I'm about to start fabbing up the intercooler and supercharger mounts and pipes, and can use either type of intercooler : endtanks on the right and left or endtanks on the top and bottom with inlet and exit on the same side of the core. I would rather use the latter type so I can put the supercharger on the passenger side of the engine bay and keep the stock NA IM which has its inlet on that same side. I'm thinking the large endtank (top and bottom) intercooler configuration is less restrictive than an equally sized cooler core with a long path through it and small entrance area.

Evil aviator and others with fmic experience, please comment. :D

Thanks in advance. :)

*edit* here is what I'm thinking would work out the best, something like this:

http://cgi.ebay.com/ebaymotors/ws/eB...category=33742

I'm curious. How are you planning on mounting this intercooler?

Ha ha, no one commented. That's fine, I did some research.

I was going to mount such an intercooler in front of the radiator using welded on brackets and holes cut thru the radiator support structure for the pipes.

That layout has always been preached by Corky Bell: http://www.bellengineering.net/Pages...ercoolers.html

As mentioned, clearance will be an issue and one still needs a good enough height to the core for effective heat exchange.

I didn't say anything initially, cause I know it's going to erupt into a nasty bitch fest.

Too much variables to consider, and then you got the low-ball group that's always going to argue why people pay big money for their intercoolers.

I am partial to the A'PEXi and ARC IC cores myself.
I don't like Spearco's blasting of tube-fin IC cores.
I'll just leave it at that. :)


-Ted

I don't like high intake temps. That's all I'm gonna say . . whatever brand is on the core is fine by me if I'm still seeing 30 degrees over ambient @ 8 psi coming off an eaton . .

So u like Apexi and ARC . . tell me about them. I'm not into this boost stuff too much so I have an open mind. State ur case for favoring that which you consider to be the optimum configuration.

Here's an IC made by Pettit for their 20B conversions:
https://www.rx7club.com/showthread.php?t=280049

I thought that seemed like a good layout, too, so I bought and will be using it with a single turbo 13B.

-Max

Keep in mind that a Roots-type supercharger compresses the air in the intake manifold, not in the supercharger unit like a centrifigual compressor. Therefore, I don't think a front-mount is such a great idea. I think it would be better to use an air-liquid intercooler or top-mount air-air intercooler that is integral with the intake manifold.

See some air-liquid designs here:
http://www.superchargersonline.com/p...rcoolers_water

More about intercooers in general:
http://www.are.com.au/techtalk/intecoolersMR.htm

Hehehe, that's because they don't understand the concept of fin count, spacing, sizing, and the fact that aluminum corrodes in the junk yard and loses its cooling effectiveness over the years. However, a low-budget intercooler is better than no intercooler. :)

I guess you didn't read George Spears' book then?

A'PEXi cause they claim their IC works well but doesn't have that much of a restriction blocking the incoming airflow to cool everything else (i.e. oil cooler and radiator).
This IC has a very "loose" fin density facing the ambient air charge, and the "fins" are sharply angled to promote better airflow.
Anyone who has run a FMIC (on an FC3S) knows how badly the oil cooling (and radiator) suffers.
We're running one on an FD3S locally with very good results.

I just saw the brochure on the ARC unit from last years SEMA '03.
It's a bar-plate design, but it has slightly radiused ends to promote better airflow through the core.
EVERYTHING from ARC is stupid expensive, so expect ridiculous prices for their stuff.


-Ted

Sorry, don't like the design due to the unnecessary 90-degree bends in the intake path.
It looks like compromise in airflow was taken for ease of installation.


-Ted

The thunderbird oem installation features a front mount intercooler directly after the blower, leading to the intake manifold.

An fmic with a roots would induce a large intake volume between the blower and the intake ports where air would need to be compressed . . and this volume could induce some "boost lag" of a fraction of a second or so, although I'm not unhappy with that, considering the instant torque produced by positive displacement superchargers on throttle opening, and the shock placed on the drivetrain because of it.

My setup will be mostly a temporary roots setup, and later I will swap in a Whipple lysholm compressor (yes compressor, not blower) which has an internal compression ratio.

Thanks for the comments. I haven't taken my thermal fluids classes yet. ;)

The thing about that configuration is all the extra volume in the endtanks that must be compressed before the charge can reach the manifold. If the tanks were at the sides on that IC there could be a significant reduction in volume with the same cooling capacity.

The thing I found was that it is fairly hard to get real numbers from any of the producers of ICs. Why I am not certain, but they sure like to say theirs is the best with out a lot of information to back up there claims. I personally just went with a core that fit my allotted space the best, so I ended up with a spearco tube and fin. It doesn’t have the least pressure drop for its size (bar and plates are better for a given size usually) but it flows great and has good cooling for its size, and it fit into my allotted space very well.

Here is what the internal tubes look like of the spearco tube and fin
https://www.rx7club.com/attachment.p...chmentid=67373

You will like your fluids classes; its all stuff that makes sense and you can just look at things and quantify the effects of certain setups and configurations immediately. I know it helped me a lot in how I made my IC setup, and being able to make better decision on how to put it together and not worry about smaller issues that didn’t matter as much and concentrate on the important factors more.

So, with what you know about engineering at this point, would you generally expect to find better engineering on a Ford Thunderbird or on a Jaguar XJR6?

Theyre both fords, so what does it matter?

Correct, that would be the answer given by somebody whose sum total of automotive knowledge comes from reading mass-consumption automotive magazines that focus on such pedestrian issues as Ford buying Jaguar in 1989. Now, what would be the answer given by one of our future engineers who would hopefully have a better grasp of the depth of that question rather than getting stuck on a simple corporate semantics?

I would strongly suggest that the right way to intercool a roots is with an air/water "aftercooler". Other fords use this type (lightning with the M112) and so does the symbol of German engineering in my mind, the AMG SL55 493hp 5.5l roots charged V8 Mercedes engine.

Hmmm . . yeah the supercoupe M90 is said to be the least efficient trim M90 there is, perhaps due to the porting, throttle body arrangement and fmic. I really don't want to use one but I'm on an engineering student's budget here. ;) I really would rather spend eight hundred bux on a used whipple 1600 (one ended on ebay for that price a couple weeks ago). :eek:

Would the issues of aftercooling configuration be covered on Corky Bell's book _Supercharged_ ?

Thanks!

*edit* thanks for the links, great info there.

Jaguar.
As backward as the Brits engineering seems sometimes(no offence to anyone form the UK) they actually know what they are doing, take the Rolls-Royce Merlin engine for example, by the end of the second world war they had doubled the hp they had at the start of the war.

Yes, Corky Bell covers intercooling in his Supercharged! book, but that chapter is really just an updated version of the same chapter in his Maximum Boost book. Although he does cover some good intercooling issues, I have yet to match his intercooler math with real world conditions, nor has anybody else that I know who has tried crunching those numbers. On the good side, he covers the construction of intercoolers and intercooler systems rather well for a book intended for average people.

I think the best parts of the Supercharged! book are the supercharger chapters (one chapter for each supercharger type), the chapters on properly mounting the supercharger, belt and pulley selection, and the testing chapters. This book is especially good for those who intend to fabricate their own supercharger setup, but even the couch potatos will enjoy reading about the different types of superchargers. The book is not nearly as technical as a college textbook, but that's why it's more fun to read. :)

88integraLS, I have a Lysholm off of a Millenia S that I will sell you at a reasonable price if you want. That is a 2.4L swept volume miller cycle engine, I believe (so a 2.6L total volume)- should be right for our 2.6L rotary?

It did have some oil on the rotors when I recieved it- not sure if it was one that was dealer pulled for the oil leak warranty deal, but "3rotors" (mazda tech) on this forum thought it would be rebuildable if it was one of these leakers.

It is long, w/ the intake extension it is 16" long- maybe 13" w/ a different extension. This does create some mounting issues as you do not want to drive it off a pulley too far off the front of the crank as SC rotaries have enough problems w/ E-shaft flex even on a decent set-up. You could make a jackshaft or an offset pulley on the SC I suppose.

My only concern about the millenia S lysholm compressor is that it has oil feed / return ports that I would need to plumb, and part of the reason I'm not doing a turbo swap is so I don't have to deal with engine based oiling of the compressor.

Does it have the oem throttle body with it?

It might be a bit small for a street ported 13B but I was strongly considering using the millenia S compressor before I learned of its non-self contained oil supply. What's your take on this? I've yet to see a millenia S lysholm compressor in the flesh.

And about intercoolers, I'm finding in some of the websites I've visited that bar/plate cores are a little more restrictive than tube/fin but cool more, although it really depends on how well the core is made and engineered. Would you engineers say that my thinking is correct on this?

I just got done reading this thread, just a couple of things. Everybody always says they don't want much pressure drop across the IC, but doesn't lower temp=lower pressure? And what brand is a well engineered bar/plate IC?

BTW, I've noticed that jag's are starting to share some parts from the ford part bin.

George Spears (Spearco) says that both types have roughly the same efficiency, but the bar & plate has more mass and surface area for a given external dimension which makes it good for a heat sink effect, while the extruded tube type is lighter and can respond to temperature changes more rapidly.

It's all about DENSITY, not necessarily temperature or pressure.

Density = Pressure / (Gas Constant * Temperature)

Therefore, an increase in pressure will yield an increase in density, which is why turbos and superchargers increase engine performance. A decrease in temperature will yield an increase in density, which is why cold air intakes and intercoolers increase engine performance.

Unfortunately, a turbo or supercharger heats the air when it increases the pressure, so the air density is not increased as much as it would without the temperature increase. Intercoolers are designed to help make up for this density loss by decreasing the temperature. Unfortunately, the end tanks and core of the intercooler create drag, which reduces some of the air pressure, although the density is still increased some due to the temperature reduction.

Basically, it's a constant battle of pressure vs. temperature in an attempt to achieve more density.

Spearco

Good :)

Hopefully, the better Jaguar technology will creep into some of Ford's performance models, and also hopefully some of Ford's lower-priced (but still good) parts will make their way into the Jaguar models.

my dad leased an x type, and its a ford with nicer seat trim, and some quality control on the engine. every part is stamped jaguar, but it looks like a tribute to me.