FMIC's

[Evodelta]

I must mention one thing, when talking about intercoolers - the airflow that goes to it to cool it.
Don't forget why they call the subi intercoolers interheaters

I totally agree that the OEM should be better than this



But than again ... 9" against 10" of the OEM, but B&P design ... compared to the "pathetic" airflow the stock IC receives ... guess what, that IC cools a lot better.

Does it cool better? Have you tested it?


Some good points, they kick off another chapter - Ducting.

You have to ask if the Subaru design is so bad then why are they still using it after all these years? Correct ducting to a 'cooler will force the air through it making it very efficient, it's only an 'interheater' when not moving, but then no 'cooler works at stand still (unless it has a fan fitted).
FMICs cannot be ducted easily so the air can go around them instead of through - which it does as it will always take the easiest path.

Some good ducting pics:

Grp A integrale, this has a small compact intercooler so they had to make the best of it with an excellent duct, see how it is smaller at the entrance than where it meets the 'cooler face, the air has no way of whirling round and coming back out, it is forced through the intercooler matrix where it cools it down:



Ducting on a race car:



See how the rad is fitted at an angle? This makes the air struggle to get through the core and gives better cooling, it also allows a bigger core to be fitted in the same height.

[Evodelta]

I know is a long shot...how much BHP you think this IC can support??

There is a mathmatical equation we can do to size an intercooler, I did it when designing mine. I will see if I can dig it out and post it up, it does suggest a really big intercooler though.

[j1v]

Does it cool better? Have you tested it?

I admit it - no. I know the temp drop was pretty good at the dyno, and was told by other people the stock was pretty bad. I have not driven that car stock to have some useful data to prove it

Some good points, they kick off another chapter - Ducting.

Ducting is the way to effectively cool a intercooler, agree on that. But I do not agree the point that FMIC cannot be ducted.

You have to ask if the Subaru design is so bad then why are they still using it after all these years?

You know very well why - response

I never said long FMIC are better at everything, they are better at cooling the intake air, especially at high boost. Pressure drop and losses ... like you said, we have to look at the most OEM IC fitted on real turbo cars and will get the best design and position

[Evodelta]

I admit it - no. I know the temp drop was pretty good at the dyno, and was told by other people the stock was pretty bad. I have not driven that car stock to have some useful data to prove it



Ducting is the way to effectively cool a intercooler, agree on that. But I do not agree the point that FMIC cannot be ducted.



You know very well why - response

I never said long FMIC are better at everything, they are better at cooling the intake air, especially at high boost. Pressure drop and losses ... like you said, we have to look at the most OEM IC fitted on real turbo cars and will get the best design and position

Well, it is not so good to enter a debate with no facts....

Response, yes, power and economy aswell. I have no temp tests on a Subaru, but I bet it cools as good as any other, the Japanese are not stupid.

It depends on how far forward your FMIC is if you are to get a good duct on it, I know mine isn't - it is pressed up against the bumper.

True, a longer intercooler tube will produce cooler air, but it is what we call 'The law of diminishing returns' after the first few inches (7 - 12) the rest only does a little bit more and is offset by the fact that the air has gone to sleep and not even enough can fit through...

[j1v]

Well, it is not so good to enter a debate with no facts....

Response, yes, power and economy aswell. I have no temp tests on a Subaru, but I bet it cools as good as any other, the Japanese are not stupid.

It depends on how far forward your FMIC is if you are to get a good duct on it, I know mine isn't - it is pressed up against the bumper.

True, a longer intercooler tube will produce cooler air, but it is what we call 'The law of diminishing returns' after the first few inches (7 - 12) the rest only does a little bit more and is offset by the fact that the air has gone to sleep and not even enough can fit through...

No arguing, but you ,as much as I do, are being too general too

You say only the first few inches (7-12) are cooling - but at what temp of the air entering the cooler ?

For example it will not be the same distance if the incoming air is 40 degrees hotter than ambient and if it is 100 degrees hotter than it.

So at different levels of boost that distance will be different.

So, if a longer cooler gives me the ability to run more boost, without going too hot to cause detonation, I will get more power. Even if that will not be the most efficient way because of a bad design IC it will be more than the power achieved with a maxed out, perfectly designed, but small (because of dimension constraints) intercooler

[#84]

Interesting that the heat transfer occurs in the first two to three decimeters. I was first thinking that maybe it was due to laminarisation of the flow, but that isn't likely with the tube&fin concept. So, if the core and airflow is really good it do what it can in a short distance and then there is not much more to get from it.

To something completely different. If you don't modify the entire front and cut up the bumper beam, I would like to compare the Q4 with a mid-engine car, in terms of cooling. In mid-engines the air-to-water-to-air charge air coolers are widely used. An din the very well built Ford Focus RS. I know that the air-to-air has some advantages, but since (A) the main radiator has problem to cool the engine enough during hard operation (track day etc) (B) placing an intercooler in front of the radiator makes A even worse and (C) the water system has an acumulator effect so that you can store cooling capacity when the throttle is closed - I am tempted to say that a air-to-water-to-air charge air cooler would be the better choice for the Q4.

I have a Garrett charge air cooler on the shelf which is as big as two bricks on top of each others (2,1 liter) and did cool 100 C at 720 hp Diesel (~1300 hp petrol) with only 0,1 bar pressure drop. The water temperature was approximately 30 degrees. I have seen some diagrams from air-to-air intercoolers and can say that nothing is near this charge air cooler. It is definitelly worth a thought.

/A

[Evodelta]

No arguing, but you ,as much as I do, are being too general too

You are playing the theorist and have no facts. You have jumped in before I have finished with my theory, we will see some facts when I have explained everything.
Let's not call it arguement, let's call it debate, I can debate with you and I respect your point of view.

I just don't agree with it.

You say only the first few inches (7-12) are cooling - but at what temp of the air entering the cooler ?

For example it will not be the same distance if the incoming air is 40 degrees hotter than ambient and if it is 100 degrees hotter than it.

So at different levels of boost that distance will be different.

So, if a longer cooler gives me the ability to run more boost, without going too hot to cause detonation, I will get more power. Even if that will not be the most efficient way because of a bad design IC it will be more than the power achieved with a maxed out, perfectly designed, but small (because of dimension constraints) intercooler

If the air entering an intercooler is too hot then you have the wrong turbo fitted or you are running too much boost on a turbo which is too small (same thing).

So what you are saying (your theory....) is that you have an intercooler which is badly designed so it strangles the engine making it lower powered and laggier than it could be, but then claws some back by being super efficient on the cooling side of things?

You think that you cannot have your cake and eat it, but I think that I can.

[Evodelta]

Interesting that the heat transfer occurs in the first two to three decimeters. I was first thinking that maybe it was due to laminarisation of the flow, but that isn't likely with the tube&fin concept. So, if the core and airflow is really good it do what it can in a short distance and then there is not much more to get from it.

To something completely different. If you don't modify the entire front and cut up the bumper beam, I would like to compare the Q4 with a mid-engine car, in terms of cooling. In mid-engines the air-to-water-to-air charge air coolers are widely used. An din the very well built Ford Focus RS. I know that the air-to-air has some advantages, but since (A) the main radiator has problem to cool the engine enough during hard operation (track day etc) (B) placing an intercooler in front of the radiator makes A even worse and (C) the water system has an acumulator effect so that you can store cooling capacity when the throttle is closed - I am tempted to say that a air-to-water-to-air charge air cooler would be the better choice for the Q4.

I have a Garrett charge air cooler on the shelf which is as big as two bricks on top of each others (2,1 liter) and did cool 100 C at 720 hp Diesel (~1300 hp petrol) with only 0,1 bar pressure drop. The water temperature was approximately 30 degrees. I have seen some diagrams from air-to-air intercoolers and can say that nothing is near this charge air cooler. It is definitelly worth a thought.

/A

Some excellent points, can I ask if we get clear of discussing air cooling first and then move onto water cooling later? And could you also get some good pictures of it, especially of what the core looks like inside, it sounds very interesting, what was it taken from?

[#84]

Yes, we can take water cooling in sa separate thread.

The core comes from NASA's "space suits" for heating the oxygen the astronauts breathe. So it is an old desig today.

This one comes from a Scania DSI9 Marine engine (early 90's). The unit was used as a pre-cooler when developing the current 720/750 hp range of Yanmar pleasure craft engines. That was when I saw the impressive results and sourced one slightky used for my own.

[j1v]

You are playing the theorist and have no facts. You have jumped in before I have finished with my theory, we will see some facts when I have explained everything.
Let's not call it arguement, let's call it debate, I can debate with you and I respect your point of view.

I just don't agree with it.

If the air entering an intercooler is too hot then you have the wrong turbo fitted or you are running too much boost on a turbo which is too small (same thing).

So what you are saying (your theory....) is that you have an intercooler which is badly designed so it strangles the engine making it lower powered and laggier than it could be, but then claws some back by being super efficient on the cooling side of things?

You think that you cannot have your cake and eat it, but I think that I can.

I too do respect your theory, and even agree with most of it
Just give me an answer why the hell did alfa fitted that waterspray system of the intercooler on this car ???

[Stuntz]

Talking frome experience Subaru Group A rally car Whit bang and waterspray ( water and some alcohol) intake temp 36 celsius ambient temp was 28 celsius

[Evodelta]

I too do respect your theory, and even agree with most of it
Just give me an answer why the hell did alfa fitted that waterspray system of the intercooler on this car ???

Well I don't know anything about Q4s, so I am the wrong person to ask really, some suggestions:

Homologation purposes.

It was the 'thing' to have back in the day, a trend or a novelty, Subaru used to fit them as standard, I don't know if they still do.

Because the intercooler is crap.

[Evodelta]

Talking frome experience Subaru Group A rally car Whit bang and waterspray ( water and some alcohol) intake temp 36 celsius ambient temp was 28 celsius

Is that IC waterspray or water injection? Water injection usually has a water/methanol mix.

[Stuntz]

Ic waterspray

Q4 has waterspray because of homologation ppurpuses ! Waterspray substantialy lowers intake temperatures quite simple pyhisical explanation....

[j1v]

Is that IC waterspray or water injection? Water injection usually has a water/methanol mix.

IC water spray , not water injection.

Like I said, the stock IC not that bad, actually it is pretty good, the problem is the q4 design (very low front) and the lack of air to the cooler. That is my opinion, but, like I already said, never drove a stock Q4. However, have a couple of friends around with experience, who said the stock Q4 was very different with/without water in the thank in the trunk, and that tells me one and only thing - the stock IC is not that efficient.

However, with the cheep ebay FMIC i have dynoed the car running 1.3 bar and it worked very fine (by memory it was something about 10 degrees above ambient) and as you very well know, the airflow on the dyno is not at all near to the real airflow of a running car.

Somebody here could give you a pic of the hole in the bumper for the stock intercooler, I checked and I don't have it. But it is really patethic

[Evodelta]

Putting alcohol into a IC water spray is quite expensive (for us), but it is clever, why?

Water must be sprayed very finely onto the core because it is the action of evaporation which takes away the heat, if the spray is too heavy and the water does not evaporate then you might aswell have not bothered. Alcohol laced water will evaporate quicker than pure water and therefore do the job more efficiently.

[axaQ42]

However, with the cheep ebay FMIC i have dynoed the car running 1.3 bar and it worked very fine (by memory it was something about 10 degrees above ambient) and as you very well know, the airflow on the dyno is not at all near to the real airflow of a running car.

Somebody here could give you a pic of the hole in the bumper for the stock intercooler, I checked and I don't have it. But it is really patethic

Do you know how would the original IC handle the same ??

[Stuntz]

Putting alcohol into a IC water spray is quite expensive (for us), but it is clever, why?

Water must be sprayed very finely onto the core because it is the action of evaporation which takes away the heat, if the spray is too heavy and the water does not evaporate then you might aswell have not bothered. Alcohol laced water will evaporate quicker than pure water and therefore do the job more efficiently.

Exactly! You have to generate fine fine mist not drops of water, what most of people do whit strobes for celaning the windscreen you have to use finer strobes. Windscreen fluid is also more efficient for cooling (but only winter version wich has alcohol in it ) Italian rally driver cheat on imprezas so that they put dry ice on the IC and also blocks of ice cubes in water tank.....

[Evodelta]

IC water spray , not water injection.

Like I said, the stock IC not that bad, actually it is pretty good, the problem is the q4 design (very low front) and the lack of air to the cooler. That is my opinion, but, like I already said, never drove a stock Q4. However, have a couple of friends around with experience, who said the stock Q4 was very different with/without water in the thank in the trunk, and that tells me one and only thing - the stock IC is not that efficient.

However, with the cheep ebay FMIC i have dynoed the car running 1.3 bar and it worked very fine (by memory it was something about 10 degrees above ambient) and as you very well know, the airflow on the dyno is not at all near to the real airflow of a running car.

Somebody here could give you a pic of the hole in the bumper for the stock intercooler, I checked and I don't have it. But it is really patethic

The way to check if the duct is working is with a Dwyer Magnahelic air pressure guage, they do not cost much:

http://cgi.ebay.co.uk/Dwyer-Magnahel...3286.m63.l1177

Ideally you want one in front of the 'cooler and one behind as you can test in one go, it needs high pressure in front and low pressure behind to make it work.

You might be surprised, it may work ok, just don't scrap something because you 'think' it may not be ok, without proof and facts. See my last post on how water spray works, without any airflow it will not work....

Remember also there are many people who think they feel power:

"Wow, I filled my car up with Shell V power, I can really feel it, it's loads faster!"

Yeah right, what you are feeling is a large hole in your wallet giving you a false warm glow........

Forums are full of 'My mate did this and it was really good" etc, etc. No facts, no figures, just talk.

Me? I like facts, the bullshit stops here....

[j1v]

No I don't. Also, I don't have the exact numbers from that dyno, but if someone has dyno runs with the stock cooler and temp data from it, I could always call the guy, and receive my numbers.

The next runs (1.9 bar) were already with the bigger cooler (the one that I see has become quite popular already here )

The biggest, that is fitted right now, because of the expected enormous heat from the eaton supercharger is not dynoed yet

[Evodelta]

Exactly! You have to generate fine fine mist not drops of water, what most of people do whit strobes for celaning the windscreen you have to use finer strobes. Windscreen fluid is also more efficient for cooling (but only winter version wich has alcohol in it ) Italian rally driver cheat on imprezas so that they put dry ice on the IC and also blocks of ice cubes in water tank.....

That's not cheating, that's using your head.

[Stuntz]

Its cheating. It is specificaly written in FIA rulebooks . I miss the sound of high compression Meth injected cossie Group A engine!

[j1v]

OK you want facts. There are a few q4's here over 300hp. Some of them even more. Which one of them runs the stock intercooler

http://www.redline.lt/magazine/featu.../article/12/1/



this is the only one that comes to my mind, and guess what - 1st it runs a grale cooler, next it is running without one of the hallos, and very possibly with a modified duct. I still believe the cheap ebay FMIC is the easiest and best IC for high boost without modifying the front bumper

On that pic up there - the 4 wholes, next to the halo is the place that the stock IC gets its air

[Evodelta]

If they fitted a decent intercooler they would have even more power...

[axaQ42]

It would really help if we had some results from testing a FMIC like j1v told versus something like that (from those simple calculations it looks like that it has almost 90% more flow area then that j1v told about)in the original place.

So we could estimate what is better...a IC with less flow area but in better position(more air flow) or a better IC with more flow area but less air flow....hmmm...