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Old 03-11-2004, 04:24 PM   #1
TurboRex
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Default Best Intercooler Design

I was all set to get a fmic until I talked with Bell Intercoolers about ic design. They stated that you do not need much length. Typically, 10 inches is sufficient and any longer will only provide pressure loss (very little additional temp loss). For flow requirements, you mainly look at width and height (number of tubes). After hearing what they had to say, I realized that our tmic's are of the design they recommended and fmic's are not.

I am confused at this point since most people that have installed a fmic claim hp increases either by a lower charge air temperature and/or less pressure loss. I am wondering if this is the ol theory vs. real world type argument. In any case, it would be nice to hear some thoughts on this from people with real world experience or that have tested and have proven results. I had made up my mind on what I wanted and now do not feel comfortable that I have enough info. to make the proper decision.

thanks,

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Old 03-11-2004, 04:47 PM   #2
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Here's an idea I came up with when I still had a shop hookup that liked to do fabrication. Do a bottom to top flowing setup with a reversed intake manifold. Remove your AC condenser, and space your radiator back a few inches, replace the fans with low profile ones. The charge air would enter the bottom end tank from the passenger side, the turbo compressor would be clocked about 180 degrees - short piping. The top end tank would taper up to an oval shaped pipe that would squeeze between the frame and the top of the radiator, then go directly into the intake manifold.

This was the most efficient setup I could think up for the car - it uses very short piping, and a short, wide intercooler core. Just requires a good bit of custom work. As it is, I'm just going to end up with a DR500.

Kevin
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Old 03-12-2004, 01:40 AM   #3
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Quote:
Originally posted by Red Rocket
Here's an idea I came up with when I still had a shop hookup that liked to do fabrication. Do a bottom to top flowing setup with a reversed intake manifold. Remove your AC condenser, and space your radiator back a few inches, replace the fans with low profile ones. The charge air would enter the bottom end tank from the passenger side, the turbo compressor would be clocked about 180 degrees - short piping. The top end tank would taper up to an oval shaped pipe that would squeeze between the frame and the top of the radiator, then go directly into the intake manifold.

This was the most efficient setup I could think up for the car - it uses very short piping, and a short, wide intercooler core. Just requires a good bit of custom work. As it is, I'm just going to end up with a DR500.

Kevin
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Old 03-12-2004, 11:38 AM   #4
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Default

That's interesting, but it fails to address his question of TMIC vs. FMIC.

I do not know the answer you are looking for, but I can tell you that I have read something very similar to what Bell told you with regard to the top mount. This person also mentioned that consistent airflow was a big factor in IC efficiency, i.e. ensuring that the scoop seals properly to the IC.

I have been wondering myself about the need for these huge FMIC's. I believe one of the issues with them is poor throttle response, which kinda makes sense if you consider that the larger volume of the FMIC will take longer to fill. I think I realize that's much more to it than that.

I'm not Mr. Wizard, obviously, but this is an important topic that I would like to hear an intelligent answer on as well.
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Old 03-12-2004, 11:54 AM   #5
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As far as TMIC vs FMIC, there are a lot of threads on this already in both the 2.0 and the 2.5 forums.

Fact: TMIC is way more prone to heat soak.

Fact: While the TMIC will cool efficiently at certain levels, it will never cool as consistantly over a long period of time as a FMIC.

I also think that most TMIC's won't flow the volume needed by the LARGE turbos.
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Old 03-12-2004, 02:42 PM   #6
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When in dout look to the roots of the car....wrc....i dont understand why more people dont offer/utilize a simalar set up. with the intercooler in the front, but up high. of course a different hood is needed.

sorry i dont have a pic of it, maybe someone will be nice enough to host a pic of it.

btw. the intercooler pumbing of the wrc car has the best of both worlds. first it has very little volume; reversed manifold, a somewhat small intercooler, and minamal piping. second its not right over the motor, so less heat soak. with a reverse cowl hood, air can flow though very well.
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Old 03-12-2004, 03:07 PM   #7
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I was very interested in the IC from the WRC and Gp N cars shown down on the page here:

http://www.tecno2.co.uk/radiators.htm

but the finances weren't friendly enough to go ahead. I see this design as the best of both worlds - shortest piping and lowest volume with FM. I tried (albeit half assed) to get some info from these guys and never heard back.

BTW, another option for the TMIC is to look into electric fans.
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Old 03-12-2004, 03:21 PM   #8
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How about a custom setup something like this:





These are taken from 2000vf800's custom wagon rebuild.

http://forums.nasioc.com/forums/show...hreadid=476026
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Old 03-12-2004, 03:37 PM   #9
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Since my post, I have done some research and came to the following conclusions:

1) You have to properly match the ic to the turbo, motor size, etc. General statements of x is better than y will not provide any real help.
2) the core of tmic's should flow much more air than most fmic's. This is based on the fact that there is more area to flow through (tmic size of 4.5 inch thick by 24 inch tall vs. fmic size of 4.5 inch thick by 10 inches tall). You can simply have more tubes to flow air through on a tmic. However, since space is limited the end tank before the throttle body leaves alot to be desired. Theoretically, a good tmic should be able to flow more air with less pressure drop than any fmic.
3) FMIC's should be able to provide colder temps IF you are pushing alot a high cfm. Bell may state that 10 inches is plenty of length but there are just too many examples of people showing much cooler charge air temps with fmic's even if you take out heatsoak. This has to be a function of tube length where fmic's have at least two times the length.

Greg
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Old 03-12-2004, 03:44 PM   #10
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WOW, that must be a monster. whats going on with that intake manifold. its huge!!! obiously all custom work = $$$$$. i wish a vendor would similate a wrc intercooler/turbo kit for sti/wrx/rs.
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Old 03-12-2004, 04:10 PM   #11
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How about an air to water TMIC. Mount a heat exchanger up front in place of the FMIC. Small electric pump to circulate the water. Resivior capable of being filled with ice (1/4 mi). Very easy to lower intake temps well below ambient temp (at least for a short time) and a very efficient way to eliminate heat soak.
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Old 03-12-2004, 04:11 PM   #12
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Assimilate or simulate?

Check out my link. I don't know if it's a kit or just the core. It costs around $1900 though. If it is a kit, I doubt it includes the reversed intake manifold.

The problem with water-to-air ICs is that they transfer heat between ambient and water, then water to air, so you get an approach temperature (dT) between the ambient and intake temp that is much higher than air-to-air (on the order of 30-50 F higher intake temp).

Just put a two stage water injection system on. It helps reduce heat soak, and improves ping resistance.
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Old 03-12-2004, 04:47 PM   #13
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Wacky Idea:

To prevent heat soak how about a timed release of CO2 on to the TMIC?

Setup a wide spray nozzle similar in placement and function to the STi's IC spray nozzle. Run braided steel hose from the spray nozzle down to the engine compartment where the CO2 'bottle' is stored. Setup a temperateure based timed release via an air temp sensor that tells a circuit to release a 2 second release of CO2 directly on to the TMIC and/or into the airflow onto the TMIC. CO2 is environmentally safe, abundant, non-corrosive to aluminum, cheap to purchase, easy to find, requires no license to own/transport, can be stored in large volumes under pressure and exits at temps well below freezing.

Now again I said its wacky, but it is an idea.

- Janq
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Old 03-12-2004, 06:33 PM   #14
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Ok, the questions I have had for a long time, What is too hot?? I am currnetly runnig a stg2 wrc, but I am running a autometer dual probes temp gauge (once before the ic, and one after the ic before the tb. My post ic temps are usually around ambient to a little over (max 10 over). I installed a short ran, and my temps when through the roof (now run about 15-20 over ambient). I am running a sti scoop with a splitter which helps cool things off after heatsoak. I am going to install a 18g with a txs v2 tmic later this spring, and start my testing all over again. I know one thing for sure, there is going to be no short ram. I ran a couple of track days, and I was pushing a constant 300 degrees out of the turbo (stock td04) and the post ic temps never went over 110-115 (was about 85-90 outside).

Russ
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Old 03-13-2004, 01:31 AM   #15
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Quote:
Originally posted by WRX1
Ok, the questions I have had for a long time, What is too hot?? I am currnetly runnig a stg2 wrc, but I am running a autometer dual probes temp gauge (once before the ic, and one after the ic before the tb. My post ic temps are usually around ambient to a little over (max 10 over). I installed a short ran, and my temps when through the roof (now run about 15-20 over ambient). I am running a sti scoop with a splitter which helps cool things off after heatsoak. I am going to install a 18g with a txs v2 tmic later this spring, and start my testing all over again. I know one thing for sure, there is going to be no short ram. I ran a couple of track days, and I was pushing a constant 300 degrees out of the turbo (stock td04) and the post ic temps never went over 110-115 (was about 85-90 outside).

Russ
Let's assume power = a constant * airflow, which isn't a bad assumption. We know the ideal gas equation, PV = nRT; and it's a fair assumption for air at the low temperatures and pressures we are dealing with.

Let's say the ambient temp is 90F. Let's see what happens if you switch over to an FMIC and it's temperature is only 10F above ambient. That would be an air increase (power increase) of 2.7%. If the exchanger was super efficient it might do 7F over ambient, which would be a 3.2% power increase.

This of course is assuming the same pressure drop across the intercooler, which is probably not a good assumption. We also need pressure drop data along with the temperature data. If the FMIC has 0.5 psi less pressure drop than the TMIC, that would be approximately 1.7% extra air (power). So, you may manage 5% extra HP tops with the FMIC for the stock turbo, or about 10-15 HP, not really worth it IMO.

There are a few things that are important to remember in the FMIC vs TMIC debate. The WRC car is an intake limited car. Every 0.1 psi of pressure drop matters with an intake limited vehicle. Anything you can do to reduce the restriction in the flow path to the throttle body (FMIC), no matter how small it may seem, is probably worth it. Also, anything you can do to displce air (hence the WRC car running water injection), is worth it. If I want a few extra HP because my TMIC has a non-optimal pressure drop, all I have to do is turn up the boost a little. The WRC car has no such luxury due to it's intake limited nature. I think comparing the design for an intake limited vehicle to the design for a non-intake limited vehicle is not the best comparison.

FMICs definitely have thier place, but I don't think their place is on a car with a stock or slightly larger than stock turbo.

If FMICs were such a great idea for stock turbos I think we would see more dyno graphs flying around of the gains with just a TMIC to FMIC swap. Of course if you have a huge turbo you are going to see gains from a core capable of flowing more air.
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Old 03-13-2004, 01:38 AM   #16
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Quote:
Originally posted by Janq
Wacky Idea:

To prevent heat soak how about a timed release of CO2 on to the TMIC?

Setup a wide spray nozzle similar in placement and function to the STi's IC spray nozzle. Run braided steel hose from the spray nozzle down to the engine compartment where the CO2 'bottle' is stored. Setup a temperateure based timed release via an air temp sensor that tells a circuit to release a 2 second release of CO2 directly on to the TMIC and/or into the airflow onto the TMIC. CO2 is environmentally safe, abundant, non-corrosive to aluminum, cheap to purchase, easy to find, requires no license to own/transport, can be stored in large volumes under pressure and exits at temps well below freezing.

Now again I said its wacky, but it is an idea.

- Janq
CO2 has the ability to be colder than evaporating water, but it's cooling capacity (volume for volume or weight for weight) isn't in the same league as water. Water is an amazing fluid from a thermodynamics and heat transfer standpoint. CO2 might be good for before drag runs, but I doubt it would do much for track days or day to day driving.

And no matter how common or safe CO2 is it will never be as safe, cheap, or easily available as water.
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Old 03-13-2004, 02:17 AM   #17
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Quote:
Originally posted by Corn-Picker
Let's assume power = a constant * airflow, which isn't a bad assumption. We know the ideal gas equation, PV = nRT; and it's a fair assumption for air at the low temperatures and pressures we are dealing with.

Let's say the ambient temp is 90F. Let's see what happens if you switch over to an FMIC and it's temperature is only 10F above ambient. That would be an air increase (power increase) of 2.7%. If the exchanger was super efficient it might do 7F over ambient, which would be a 3.2% power increase.

This of course is assuming the same pressure drop across the intercooler, which is probably not a good assumption. We also need pressure drop data along with the temperature data. If the FMIC has 0.5 psi less pressure drop than the TMIC, that would be approximately 1.7% extra air (power). So, you may manage 5% extra HP tops with the FMIC for the stock turbo, or about 10-15 HP, not really worth it IMO.

There are a few things that are important to remember in the FMIC vs TMIC debate. The WRC car is an intake limited car. Every 0.1 psi of pressure drop matters with an intake limited vehicle. Anything you can do to reduce the restriction in the flow path to the throttle body (FMIC), no matter how small it may seem, is probably worth it. Also, anything you can do to displce air (hence the WRC car running water injection), is worth it. If I want a few extra HP because my TMIC has a non-optimal pressure drop, all I have to do is turn up the boost a little. The WRC car has no such luxury due to it's intake limited nature. I think comparing the design for an intake limited vehicle to the design for a non-intake limited vehicle is not the best comparison.

FMICs definitely have thier place, but I don't think their place is on a car with a stock or slightly larger than stock turbo.

If FMICs were such a great idea for stock turbos I think we would see more dyno graphs flying around of the gains with just a TMIC to FMIC swap. Of course if you have a huge turbo you are going to see gains from a core capable of flowing more air.
Take a TMIC car out on the track. Do lap after lap after lap. Tell me if your AIT's remain even slightly consistant with the firs lap or two. Now try it with an FMIC.....

I think that is where the major difference is. Oh, and an FMIC is a bit more traffic resistant than a TMIC.
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Old 03-13-2004, 10:03 AM   #18
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I did a couple fo track days, and each lap is about 1 miles or so, and ther are some failing long areas to keep wot throu, and I never went over 110 post ic temps. At the sma epoint in time, I was also do 80-100 mph, so I do have alot of air going through the ic. Also, the intake does make a difference on your post ic temps. I have see and done it, and a short ram just sitting under the hood did give me a little better throttle response, I know when it was a modified cai, I was depinitly running colder post ic air temps. The turbo itself will only heat the air to x amount. I never went over 300 degrees pre ic, until i went with a short ram. I think the highest temps I ever saw after the turbo was about 270-280.

Russ
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Old 03-13-2004, 11:22 PM   #19
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The more I read, the more I get confused on the bar & plate vs. tube & fin. My most recent reading summarized for a given ic size, bar & plate cools better, and tube & fin flows better (less pressure drop). Is that correct? Anyone have any experiences going from a tmic with bar and plate to a tube & fin front mount? I have heard some say the tube & fin lowered their boost while others say it dropped.

I can't believe how there can be so much contraversy on something that should have plenty of data to back up and plenty of people to relate their experiences.


Greg
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Old 03-13-2004, 11:46 PM   #20
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Quote:
Originally posted by STFUTuning
As far as TMIC vs FMIC, there are a lot of threads on this already in both the 2.0 and the 2.5 forums.

Fact: TMIC is way more prone to heat soak.

Fact: While the TMIC will cool efficiently at certain levels, it will never cool as consistantly over a long period of time as a FMIC.

I also think that most TMIC's won't flow the volume needed by the LARGE turbos.
Agreed but they have thier down sides...

TMICs are easyer, cheeper, and less prone to getting smashed by rocks. If you not running a 400hp turbo you dont need a
400hp IC.
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Old 03-14-2004, 02:34 PM   #21
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I'm suprised not as many people take the air/water route....
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Old 03-14-2004, 03:54 PM   #22
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Quote:
Originally posted by STiTuner
I'm suprised not as many people take the air/water route....
Cost, and weight. To keep it cool on a long track day you have to have a huge amount of water.
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Old 03-14-2004, 05:00 PM   #23
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Quote:
Originally posted by Janq
Wacky Idea:

To prevent heat soak how about a timed release of CO2 on to the TMIC?

Setup a wide spray nozzle similar in placement and function to the STi's IC spray nozzle. Run braided steel hose from the spray nozzle down to the engine compartment where the CO2 'bottle' is stored. Setup a temperateure based timed release via an air temp sensor that tells a circuit to release a 2 second release of CO2 directly on to the TMIC and/or into the airflow onto the TMIC. CO2 is environmentally safe, abundant, non-corrosive to aluminum, cheap to purchase, easy to find, requires no license to own/transport, can be stored in large volumes under pressure and exits at temps well below freezing.

Now again I said its wacky, but it is an idea.

- Janq
It's agreat idea-so good in fact that there are kits for this already out I'm thinking of getting one so that I can keep stock top mount= reduced lag over front mount andrun big hp w/out heatsoak.
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Old 03-14-2004, 09:26 PM   #24
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Water > c02 for cooling.... as already stated.
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Old 03-30-2004, 06:14 PM   #25
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Bump....

I'm leaning back towards a TMIC.....just can't decide....damnit..!

There's alot of used TXS TMIC's on the market these days....any hope of adapting one of these to fit on a STi? TurboRex, I know you are running a M2 intercooler....how hard was that to fit?

Thanks,

Kevin
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