FMIC w/WI versus A/L intercooler

[MS3 Ventura]

Why bother getting a FMIC (or upgraded TMIC) with WI (total cost about $1.3K), when you can buy a L/A intercooler for hundreds less, less weight, no hassle of filling the WI tank, etc?

[Smoker6]

As far as I understand it:
The WI decreases combustion chamber temperatures directly, allowing for more boost or timing advance, which the intercooler doesn't do directly. The I/C, being more efficient, will cool the air intake temps, pretty much (if I understand this correctly) nullifying the WI benefit on the AIT (or perhaps simply compounding the effect and lowering it further). Seeing as how it's combustion chamber temps that seem to play a big role in popping motors though, I still want the WI benefits in there - hence why I will shortly be running both (as soon as I get an L/A IC in and fix my WI lol).

[gtlaw]

in theory I like L/A IC with its short piping like the TMIC, but I have to wonder why I rarely see it being used

[MS3 Ventura]

I also don't understand why everyone isn't jumping all over an L/A IC. It's more efficient than the A/A IC, has less heat soak and in some cases is less expensive. What are we missing? Is it because the COBB AP doesn't have a map for it that people are hesitant to run it?

[bova]

aside from a custom setup there is only one L/A IC on the market. Its definately not because the AP doesn't have a map for it. For most peoples set up a FMIC is just fine. You don't have to worry about water leaks or that kind of stuff either.

[gsrtype1]

I have the ets tmic with wi and if i'm boosting for 5-10seconds straight my bat go 10-15 degrees below ambient. like if its 70 degrees out I can get my boost temps down to 50 pretty easy.

[MS6_Auburn_Fan]

While I like the idea of a L/A IC because of it's efficiency, my fear comes from what happens when the water pump fails. Granted if your monitoring your BATs you'll see them climbing and limp your way home. A/A FMIC or TMIC are just simpler and have fewer components that could fail. That may explain why they are more common. If the TT L/A IC placed the IC somewhere other than on top of the engine I would consider it.

[Smoker6]

Hopefully a fellow MSF member can bring precisely that to the table. His kit looks great to me.

[MS6_Auburn_Fan]

Originally Posted by Smoker6 Hopefully a fellow MSF member can bring precisely that to the table. His kit looks great to me.

Are you referring to bnoon it think that's who put the IC over where the stock air box was? Yea I like that set up but i'm already working on a side-to-side FMIC.

[Smoker6]

Originally Posted by MS6_Auburn_Fan Are you referring to bnoon it think that's who put the IC over where the stock air box was? Yea I like that set up but i'm already working on a side-to-side FMIC.

Yeah. I picked up his instead of the TT and he plans on trying to fit a bigger core in there TT style, but I like the side mounted one.

[bnoon]

Originally Posted by MS6_Auburn_Fan While I like the idea of a L/A IC because of it's efficiency, my fear comes from what happens when the water pump fails. Granted if your monitoring your BATs you'll see them climbing and limp your way home. A/A FMIC or TMIC are just simpler and have fewer components that could fail. That may explain why they are more common. If the TT L/A IC placed the IC somewhere other than on top of the engine I would consider it.

Actually you don't have to limp home at all, it just won't perform as well when pushed. I drove without the pump running just to find out what happens... no knock, boost temps around 100-120 degrees when pushed (would climb higher if allowed to totally soak in the heat from the radiator/etc), but while normal driving it was more than fine. I drove for a month like that logging temps and never once had anything to worry about.

[Crossbow]

Depending on the design of the pump, if fluid can continue to move through the pump with it failed, or shut off, it will do so, via the same process that continues to circulate coolant through your turbo, after the car is shut off.

Thermosiphon - Wikipedia, the free encyclopedia

Thermosiphon

Convective movement of the liquid starts when liquid in the loop is heated, causing it to expand and become less dense, and thus more buoyant than the cooler water in the bottom of the loop. Convection moves heated liquid upwards in the system as it is simultaneously replaced by cooler liquid returning by gravity.

Basically the intercooler has hot water in it, the radiator has cool water in it, the two will circulate back and forth via this process, as long as the failed (or shut off) pump does not block circulation of fluid.

Here's a video showing the most simple version of this process in action. Just watch the red food dye move, there is no pump involved.

YouTube - Solar Thermosiphon Effect in Action

YouTube - Solar Thermosiphon Effect in Action

Keep in mind that the larger the temperature difference, the greater the movement.

[bnoon]

Why does it have to be air/water vs TMIC with water/meth injection? Just put together your own air/water and put meth on it too... It's so simple a caveman could do it.

[06Speed6]

L/A is what I would run if I upgraded the tmic. It is a no brainer.

If you run the lightning pump, it is unlikely to fail and if it does it will not really hurt anything. As a bonus the pressure drop is lower, the temps are cooler, and the boost comes faster.

As far as water leaks are concerned, those are easier to fix than a boost leak on a fmic.

[sleeperstang1994]

wow that hot water cold water thing was cool. i learned something today. MR rodgers would be happy. thanks!

[blackcherryspd6]

Does anyone have any whp gains to report on this in comparision?

[Crossbow]

There are no whp gains from an intercooler. Any whp gains are associated with the vehicles boost changing.

Ask anyone posting an intercooler dyno to post a boost overlay, and they won't, because you'll just see the car producing more boost, and thus, more gain.

Basically if you get an intercooler with a 2 psi less pressure drop, you're basically using the intercooler as a boost controller, and raising your equivalent boost by 2. (The ETS TMIC does this, which is why they show roughly a 20 whp gain...guess what 2 psi gets you? That's right, 20 whp...lol )

If you use a boost controller and set the boost back to normal levels, you'll have zero gain. It's the boost adjustment that gives a gain...

[wassup61]

Originally Posted by Crossbow There are no whp gains from an intercooler. Any whp gains are associated with the vehicles boost changing. Ask anyone posting an intercooler dyno to post a boost overlay, and they won't, because you'll just see the car producing more boost, and thus, more gain. Basically if you get an intercooler with a 2 psi less pressure drop, you're basically using the intercooler as a boost controller, and raising your equivalent boost by 2. (The ETS TMIC does this, which is why they show roughly a 20 whp gain...guess what 2 psi gets you? That's right, 20 whp...lol ) If you use a boost controller and set the boost back to normal levels, you'll have zero gain. It's the boost adjustment that gives a gain...

This is a valid assessment; however, if you don't look at dyno queens, heat capacity of an intercooler core/ flow efficiency is very important. If you are doing a track day, and your intercooler is heatsoaked (whether radiator wash or engine heat), you will lose power, so cooling efficiency is very important in real world / track situations.
-Jeff at PG

[Buildabong]

in other words..

FRONT MOUNT/ TOP MOUNT SPRAYER!!!

[MS6_Auburn_Fan]

Thanks for the explanation and reassurance in regards to the pump failures. Bnoon where abouts do you live just out of curiousity? Also what time of year was it when you testing and only seeing 100 - 120 BATs? This may be something I will explore in the future to change things up.

[bnoon]

Originally Posted by MS6_Auburn_Fan Thanks for the explanation and reassurance in regards to the pump failures. Bnoon where abouts do you live just out of curiousity? Also what time of year was it when you testing and only seeing 100 - 120 BATs? This may be something I will explore in the future to change things up.

On 40 degree days, seeing 100-120 BATs without waterpump flowing. Same 40 degree days, the stock TMIC heat soaks to 120-130 at lights, and slowly goes down to 80-100 at 35 MPH. I live in Des Moines, Iowa, so we see anything from 100+ degree summers down to -40 winters and I've had the air/water installed since last summer. It was AWESOME difference on hot days, but I didn't have logging capability back then.

[MS6_Auburn_Fan]

That's pretty good. Right now I'll take anything over a TMIC. My side-to-side FMIC is only going to cost me no more $400 including relocating the windshield washer tank. ebay FTW.

[dukebrown]

80 degrees out this last weekend and my L2AIC and BATs were 124-133 cruising at 80-90mph. I still have the license plate blocking the radiator.

[bnoon]

Originally Posted by dukebrown 80 degrees out this last weekend and my L2AIC and BATs were 124-133 cruising at 80-90mph. I still have the license plate blocking the radiator.

Are you using straight water? Coolant/water mix? Water Wetter or anything like that? I'm guessing no Water Wetter, or perhaps some air in the system as those BATs are quite high for that temp. Either that, or the pump isn't flowing...

[bioevolve]

That TT GB is taking to long lol. When is yours gonna be ready?!?!?!?!
I'm itching to buy, this stock TMIC I put back on sucks arse.

[dukebrown]

Originally Posted by bnoon Are you using straight water? Coolant/water mix? Water Wetter or anything like that? I'm guessing no Water Wetter, or perhaps some air in the system as those BATs are quite high for that temp. Either that, or the pump isn't flowing...

I just threw some antifreeze in there with water since it was getting down in to the 20's for winter.

What temps are you getting after you have been running for 1hr plus?

[bnoon]

Buying everything you need to copy my design at retail prices would be cheaper than that group buy. And everything you need is listed in my thread. If you have questions, pm me, or just paypal me and I'll buy it and ship it to you.

[subparpunk03]

This comment about liquid to air intercoolers being more efficient is a gross oversimplification. You need to look at what you are planning on doing with the car, be it daily driving, road racing, drag racing, or interstellar time travel. The different applications have their pros and cons just like anything else. To make a blanket statement like "this is better! ALWAYS!" is just silly.

I am not going to factor WI into this equation.

Lets look at the pros of each setup first:

L2A: Can use ice water to get WAY low BATs, cores can be made more compact b/c you have a pump forcing water over fins for the first heat exchange so you don't need to expose more surface area to air. I think these cores can flow better as well, though I'm not 100% sure of that.

AATMIC: Relatively simple design, less piping means the turbo doesn't have to work as hard to get air to move into the engine. Only relies on 1 heat exchange (more on this shortly)

AAFMIC: No heatsoak, generally a core with more surface area than a TMIC means better cooling, and also only relies on a single heat exchange.

And now the cons:

L2A: Requires 2 heat exchanges to remove heat from the air charge, during prolonged use, ice water will melt and the liquid used for cooling can heat up to ABOVE ambient temps, dramatically reducing the efficiency of the first heat exchange.

AATMIC: heatsoak... like a mofo. Also, on this car, except for the TRZ tmic the cold pipe is a MASSSSSIVE flow restriction. Take it off and look at it, you'll see what I mean.

AAFMIC: Extra piping and larger cores generally mean more lag, and more complexity. FMICs are also susceptible to heatsoak and block a portion of air flowing through the radiator so increased coolant temps may occur, however that is a general statement and I have not noticed that happening on my car.

So whats all this talk about heat exchanges? Well, what does an intercooler do? It transfers heat from the air coming off the turbo, to the air outside of the car. In a L2A IC it transfers the heat from the boost-air to water/coolant, and then from the water/coolant to the ambient air. None of these heat exchanges are a 100% efficient process... so when you have two heat exchanges you are losing efficiency. As the water in your L2A IC heats up, you lose even more efficiency since the amount of heat exchanged depends on a temperature difference between the host media (in this case the boost air and the liquid) THEN you have to transfer the heat from the liquid to the ambient air, and that is also not a 100% efficient process...

So what applications are best suited for the different ICs? They are all fine for daily driving. I personally like the FMIC if I'm in traffic cause it takes longer to get heatsoaked then temps drop like a rock as soon as I start to move.

L2A: Drag racing... b/c you can put ice in it and get lower than ambient temps for the first heat exchange, make a few passes, stop, refill the IC with ice, etc. If you are doing prolonged racing, eventually its going to become far less efficient than an air to air setup.

FMIC: Road racing / autocross. Keeps its efficiency throughout the track event. Will be incredibly consistent, and just looks awesome.

TMIC: If done properly, and using WI in conjunction with it, you'll see nice low BATs and superquick spool. It can be good, but honestly, doesn't offer any real advantage over a FMIC if you are road racing.

[Crossbow]

Also, on this car, except for the TRZ tmic the cold pipe is a MASSSSSIVE flow restriction.

What's interesting though, is the TRZ TMIC showed the same flow as the other TMIC's on the market, even with it's custom cold pipe. There really wasn't any difference. So if the cold pipe is a restriction, it's not the biggest restriction in the equation. I found that data interesting, and it seems to be glossed over on the forums. I felt that was one of the strongest selling points of the TRZ TMIC, but didn't see any follow through with data supporting it as a restriction.

This is also one of the reasons I feel it was put on the backburner, as it's main feature didn't really pan through.

Don't forget that one of the main drawbacks of the FMIC's is that the larger units cause an increase in coolant temps....which could also happen with the Liquid intercoolers, if a large enough section of the condensor/radiator assembly is blocked from incoming airflow.

[subparpunk03]

Originally Posted by Crossbow What's interesting though, is the TRZ TMIC showed the same flow as the other TMIC's on the market, even with it's custom cold pipe. There really wasn't any difference. So if the cold pipe is a restriction, it's not the biggest restriction in the equation. I found that data interesting, and it seems to be glossed over on the forums. I felt that was one of the strongest selling points of the TRZ TMIC, but didn't see any follow through with data supporting it as a restriction.

I did not know that. Very interesting. Admittedly I have no evidence to support the stock cold pipe being a huge restriction, i just took a look at it and it appeared to have a section where it was flattened out and pinched, so much so I don't understand how it could NOT be a restriction.

Originally Posted by Crossbow Don't forget that one of the main drawbacks of the FMIC's is that the larger units cause an increase in coolant temps....which could also happen with the Liquid intercoolers, if a large enough section of the condensor/radiator assembly is blocked from incoming airflow.

Originally Posted by subparpunk03 AAFMIC: Extra piping and larger cores generally mean more lag, and more complexity. FMICs are also susceptible to heatsoak and block a portion of air flowing through the radiator so increased coolant temps may occur, however that is a general statement and I have not noticed that happening on my car.

Got that one covered, but it is a good point nonetheless and bears repeating. You are absolutely right and there are plenty of serious drivers out there that prefer a top or side mount for this very reason.

[Crossbow]

i just took a look at it and it appeared to have a section where it was flattened out and pinched, so much so I don't understand how it could NOT be a restriction.

I completely agree with you, it just didn't seem to make much of a difference at all in terms of flow. Pressure drop was about the same as the other TMIC's on the market. If it was a big restriction, should have a bit more flow...all I can figure is the intercooler itself provides more of a restriction then the piping.


If someone was willing to just make some simple ducting for the FMIC/radiator/condensor, they could probably get around the increase in coolant temps. Of course there is all sorts of things you could once the TMIC is out of the way.

Some of the subbie guys running FMIC's will use the hood scoop and associated ducting to run an oil cooler in that location. Could do a similar thing with the MS3 if you were running an FMIC, or even put an auxiliary radiator there!

B-Line Motorsports - Oil Coolers

Scroll to bottom of link to see what I'm talking about!

Oh and before people start flipping out about "But its on top of the engine, it'll get hot!" If you aren't dealing with the same 3-4 inches of thick intercooler, you can build a wrapped or coated piece of alumnium to reflect the heat off the top of the engine from directly effecting the cooler, as well as ducting the incoming air.