GT500 Cooling Part 1: The Stock Intercooler System

[Justin@VMP]

In the first post I am going to detail how the stock intercooler system works and it's specifications. In subsequent posts in this thread, I will go into the details of modifying various aspects of the system, and explore some potential issues, as I go down the path of keeping my 700RWHP GT500 cool enough to run a 20 minute road course session without heat soaking and looseing 300RWHP.

Any GT500 with higher than stock boost levels is going to have cooling problems when driven very hard at sustained high RPM in a road course type enviroment. Running the 3.7mi Sebring track during a Florida summer brings out the worst in the factory cooling system. The hot supercharger air going into the engine (due to lack of adequate charge cooling) will significantly effect engine coolant temps.

Like the Lightning and Cobra before it, the GT500 comes with a factory intercooling system.

The factory system utilizes an air to water heat exchanger in the lower front grill, a pump, a small reservoir, and another air to water heat exchanger in the Vee of the block, below the supercharger.

The stock front Heat Exchanger has 12 rows/tubes. The tubes are 1" thick and 23" long. The HE is 6" tall, and ~26" wide overall. It holds ~ 1 quart of fluid.

There is a Bosch electric water pump that is part of the system, it is the same one used on the Lightning and the cobra. These pumps are known to fail as often as every 2-3 years and 20,000-50,000 miles. On the GT500 the pump does not turn on until the Downstream Air Charge Temp (after intercooler) is already very high, Ford probably did this to extend pump life, this can be adjusted for in the tune. Some specs I found on the Bosch pump state that it pulls 2.5amps, flows up to 4GPM, up to 2.5psi, is rated for 5000 hours, weighs 2.2lbs, and has 3/4" inlet/outlets. The electrical connector on it is interchangeable with the square EV1 injector connector found on older Fords and GMs.

I do not have exact specs on the stock in-block heat exchanger yet, but I'm told its much smaller than the stock Ford GT unit. The GT500 unit is supposed to be shorter by 4-5", compared to the Ford GT unit. Even though the applications seem identical (both are 5.4L 4V mod motors), the GT had a lot more packaging flexibility due to the mid engine design. On the GT the nose drive and belt was on the front and the TB/inlet was on the back, there is a straight shot for air going into the blower. Height may not have been as much of an issue either, due to the dry sump oil pan and mid engine design, so Ford may have had more blower placement options, and thus more options for the intercooler below it. The GT500 blower discharges near the front of the intercooler, I am told the GT discharges more toward the center of the blower.

GT500 in block HE:
http://vmptuning.com/GT500/cooling/1blockintercoolerfront.jpg

http://vmptuning.com/GT500/cooling/2blockintercoolerside.jpg

That seperate area in the rear is for the BPV.

The factory intercooler fluid resvoir on the drivers side front of the engine bay holds ~1.5qts of fluid. Ford specs the system as holding 4qts total, we can deduce that the lines and in block heat exchanger contain the other 1.5qts. With a pump that is rated at 4 GPM, figure 25% for pumping losses, with the stock system you are recirculating the water every 20 seconds.

The inadequacies of the stock system at higher boost levels may not show up on the dyno, at the drag strip, or even on the street, but they will on a road course where a lot of time is spent at high RPM on and off the throttle.

The aftermarket makes larger front heat exchanger to air in cooling. The steeda unit is 3" thick, has 23" long tubes, has 13 rows of tubes, has two sets of tubes (1.5" wide), and is ~26" overall with endtanks, like the stock unit. It is single pass.

http://steeda.com/products/steeda_high_capacity_heat_exchanger.php

Fluidyne makes a similar heat exchanger to the steeda unit, but it has 3 rows of 1" tubes, whether the number of tubes makes a performance difference is not work debating.

http://www.fluidyne.com/08product1.html

Afco makes another upgrade, it is not as thick, only 2", but they make up for it by being taller by 3" (9" for theirs, vs 6" for the stock unit and the others). The afco unit is also dual pass, how much this helps is still up for debate. Dual pass provides better temperature drops, but at the cost of overall flow volume. Afco does not have the info on their site yet, so here is a link to another site:

http://www.lethalperformance.com/pages-productinfo/product-15731/afc80280ndp-afco-2007-plus-gt500-pro-series-dual-pass-heat-exchanger.html

Fluidyne states that their HE holds twice the fluid volume of the stock unit (2qts vs 1qt), I think we can safely assume the other HEs hold similar amounts of fluid.

Here is a shot of the stock front HE:
http://vmptuning.com/GT500/cooling/1stockHE.jpg

The little fins below are stock, they held on by two clips, they help direct air into the HE. You should attemp to retain these fins, or even improve upon their design, when installing an aftermarket HE. Ideally you want the radiator and HE sealed to the front grill openings on all four sides, so all the air goes through them and not around them (more on this later).

http://vmptuning.com/GT500/cooling/2stockHEfin.jpg

Back in 07 when there were not a lot of cooling upgrades available I pulled out the stock front HE and mounted a 6.5" spal electric fan to the back of it. I powered it off the stock intercooler pump circuit (had to upgrade the 10 amp fuse to a 15amp). At the same time I installed a switch in the console that allowed me to turn them on manually. By running the pump and fan I could cool the fluid in the staging lanes for drag racing, the fan will also help with cooling at low speeds and in traffic. Spal is a well known brand, don't mess around with cheap ebay fans, they may vibrate and fail early.

http://vmptuning.com/GT500/cooling/3stockHEfan.jpg

Replacing the heat exchanger requires pulling off the front bumper, because of the little hooks at the top of the factory HE brackets.

You can also install a fan on the aftermarket heat exchangers, but the thicker 3" units will require you to bend the power steering cooler up and out of the way, and make some small tweaks to the brackets for the AC condenser, to gain clearance for the fan. The easiest way to mount the fan is using special zip ties that are meant for mounting transmission or other types of cooler to radiators, they go straight through between the tubes and have foam pads. The other option is to TIG weld on bracketry, but most people do not have access to a TIG welder. At some point VMP may offer an entire package with aftermarket HE and fan.

[Justin@VMP]

With my 18psi TVS I still had cooling problems with an upgraded heat exchanger, when road racing, so I began looking at other things.

The factory fins and clips should fit onto the steeda HE bracketry, this will help slightly.

Once the Down Stream ACT (air charge temp after the in-block IC) goes above 190F, you will start to boil the intercooler fluid. If you don't go easy on it and let the temp come back down, you'll blow the entire fluid charge out, as myself and a few others found. In the past I've been told that water cools best, but boils soonest, even with water wetter added. "antifreeze raises the boiling point but henders cooling, so neither is really an answer IMO. I am looking at some other fluids to improve cooling and prevent total fluid loss if you do get too hot, more on that later.

You can figure if your air is 190F, your fluid must be at least 20-30F hotter, if not much more. At some point I will datalog fluid temps and air temps before and after, so the exact IC efficiency and temp drops can be determined.

The flow of the stock system starts with the resevoir, which then goes to the inlet side of the bosch pump. From there the fluid is pumped into the front heat exchanger for cooling, then sent up to the in block heat exchanger where the water is heated, then back to the reservoir.

The factory front HE is a huge choke point for flow, with it installed you see a steady stream coming into the stock reservoir while the system is running. With a larger aftermarket heat exchanger you will see a torrent of water going into the stock reservoir, and some foaming/aeration can occur. One of the aftermarket heat exchangers (steeda) recommends installing a restrictor at the inlet of the reservoir, to slow down the water and reduce aeration. This is good because it also builds up pressure in the in-block HE to aid in heat transfer, but it may be bad because it reduces overall potential for flow. Water is what removes heat from the air, and the more of it you can move the more heat can be pulled out (more on this later).

[Justin@VMP]

The water coming out of the in-block HE is going to be very hot in some cases, feeding it right back into a reservoir will allow it to cool quickly and re-condense. Is this the best system arrangement? I am not sure. If it was not for the re-condensing, I would almost want my pump placed before the in-block HE, then for the fluid to hit the front HE, and then into the resvoir. The pump being close to the in-block HE may help increase pressure to aid in heat transfer, then the heat gets dumped out at the front heat exchanger, and then you have cool water waiting in your reservoir to go back into the block. You could even install a restrictor after the front HE to build pressure in both HE's. However, I don't like the idea of using a restrictor in any system without also going to a larger pump, to improve overall flow. In my suggested system design above, if the water is not full re-condensed when it hits the front HE, the heat will not be as effectively transfered out of it (see discussion below).

Later this week I'll be trying Evan's NPG R cooling fluid in the intercooler system. This stuff does not boil until nearly twice the temp of water, therefore it operates near zero pressure. At the least, it should eliminate the possibility of blowing the entire fluid charge if I do overheat. At the best, it will improve overall cooling efficiency.

The Evan's guys tell me that one of the ways their stuff helps is by reducing localized boiling. When water/antifreeze/water wetter or whatever flows through a cooling system it will locally boil in hot spots like cylinder heads, this reduces heat transfer efficiency because the water vapor that is formed will not carry away any heat. I am told that is why all conventional cooling systems operate at pressure, to raise the boiling point, reduce localized boiling, and improve heat transfer. With my second suggested system design the re-condensing may be a mute point with Evan's fluid, since it should never boil in the first place.

Evan's very much stresses total system flow when addressing cooling system issues, they do not market their fluid as a magic fix. We have always been told that a restrictor or thermostat is needed to slow down the flow, and give the water time to cool in the radiator. I'm being told that a lot of the reason for that slow down of flow, is to build up pressure in the system, and improve the heat transfer of old fashion low boiling point fluids (water, antifreeze, or water wetter), this pressure reduces localized boiling. With a fluid like NPG you can strive for maximum flow to remove as much heat as quickly as possible.

[Justin@VMP]

The factory intercooler system is pretty simple in terms of fluid volume flow. There are a bunch of 3/4" lines and a decent pump. Once you upgrade the stock front HE the system really moves a lot of water. (later on I will measure actual GPM including system losses).

I did find one large potential restriction, the manifold that feeds the in-block HE is a cast piece and takes some nasty turns.

Here is what the inlet to the in-blocK HE, looks like, with everything taken apart.

http://vmptuning.com/GT500/cooling/1blockHEfeed.jpg

http://vmptuning.com/GT500/cooling/2blockHEfeed.jpg

There are two little tubes that slide in there and allow for a small degree of mis-alignment, and allow the whole system to be taken apart of needed.

http://vmptuning.com/GT500/cooling/5blockHEtube.jpg

Then the cast manifold bolts up:

http://vmptuning.com/GT500/cooling/4blockHEmani.jpg

http://vmptuning.com/GT500/cooling/3blockHEmani.jpg

Those little tubes and the manifold are a potential choke point. I may look at extrude honing the manifold and drilling out the inside of the little tubes. I may even look at upgrading the system to all 1" lines and a bigger pump.

[Justin@VMP]

I was concerned that the stock in-block heat exchanger could be a limitation, and we know that changing out that piece would be no fun. One could take a stock lower intake and modify it, but that should be avoided at all costs due to the time, complexity, and costs involved.

I did some testing on Friday that has ruled it out as a potential weak point.

I use a loaded Dynojet, so I am able to simulate on track conditions on the dyno, with 20-30 sec pulls through 3rd, 4th, and 5th gear. On Friday I did this repeatedly. I used three 3000CFM carpet blower fans, one on the upper rad, one on the lower rad, and one blowing under the car to reduce the chance of exhaust heat causing a fire.

After 90 seconds I had reached pretty severe heat soak, 220-230F ECT, and 200F ACTs (starting to blow the 15psi cap a little bit). I wish I had done a power pull to see how much had been lost, but I did not think about it at the time. The car was only running 4-5* of timing, so I'm sure it was not making anything.

I then hooked the intercooler system up to a garden hose, at first I let it run through the entire system to simulate real world as much possible (albeit with a constant supply of 80F water), but the 15psi cap blew on the reseroir. I had to run it through just the in block heat exchanger, I measured a flow rate of 10GPM, probably 2-3x the flow rate of the stock system (I will test this later).

I proceeded to simulate on track conditions again, this time it took 120 seconds to reach severe engine coolant heat soak of 230F and CHTs of 250F. The ACT's were staying 110-120F the whole time, though they did creep up slightly as the ECT's rised, due to the engine's heating effect on the in-block heat exchanger. I made one 4th gear run with the car fully heat soaked, and it only lost 40-50rwhp, due to 3-4* of timing retard from high engine coolant temps. I am going to fix the high ECT issues and detail it in another thread.

This tells us two things, one, the in-block heat exchanger is not a limitation at 18psi/700rwhp, if enough cool water can be fed to it. Second, hot air temps also put a load on the engine cooling system, and I'm sure vice versus (more on engine cooling in another article).

In restrospect, I should have restricted the GPM to 2-4, to better simulate the stock system. However, if we had to, the stock system could flow 5-10GPM, I am looking at utilizing a larger intercooler fluid style pump made my JC, or just going straight for a huge electric water pump made for cooling the engine coolant. I am going to try and get with some engineers to come up with BTU values, but I would not be suprised if our intercooler system heat loads are approaching that of a I4 or V6 engine, so a rather massive cooling system may be necesary.

[Justin@VMP]

Another component of the intercooler system is fluid capacity. If you still can not get all of the heat out of the system, with a larger front heat exchanger, better air flow through the heat exchanger, better cooling fluid, bigger lines, bigger pumps, etc, there is one more option. You can always install a larger resvoir and buy yourself more time.

Heat soak over time is a big problem, I found my GT500 only performing well for 1/2-1 full lap around Sebring (depending on how hard I was on it) before the car started to loose a lot of powe. By 10-15 minutes into the session I was finding myself letting off to allow the car to cool, rather than driving to my full potential. We are talking about droping 100-400RWHP on a 600-700RWHP car. Yes it can be that bad, once your ACT's reach 200F and your ECT's reach 235F and your CHT's reach 250F a ton of timing is being pulled to keep the motor alive, and a ton of power is lost.

Now I consider adding more fluid capacity a last resort, because of the additional weight.

You can add fluid capacity in small ways, and not add too much weight, but if you go all the way and put an 8-16gal tank in the spare tire well you are talking about 100-175lbs once you figure in all the lines, fittings, tank, fluids, etc. That is a ton of weight for a race car.

Moroso, P-Fab, and others make engine bay reservoirs that add about a gallon of fluid capacity, that is going to roughly double the overall system capacity and bring you up to 9-10 quarts. However, using our above example, you'll be going through the same water every minute.

[Bountyhunter]

So what is your recommendation for cooling at what levels of mods?

I thought it was the AFCO but I was confused by some of the comments on the Steeda unit sounded like you are using it now??

Really curious about this subject. I live in texas and I can really tell on hot days (most of the time) that timing is being pulled after blasting through the gears for a bit and my car is stock at the moment.

[Justin@VMP]

So what is your recommendation for cooling at what levels of mods?

I thought it was the AFCO but I was confused by some of the comments on the Steeda unit sounded like you are using it now??

Really curious about this subject. I live in texas and I can really tell on hot days (most of the time) that timing is being pulled after blasting through the gears for a bit and my car is stock at the moment.

I have not found the ultimate solution yet for a 700-800HP open track car, I'm still doing R&D and analyzing various parts of the system.

However, a street car is pretty easy to cool, it does not see much abuse, so an AFCO HE and fan would be fine.

[speedemon138]

I have been looking around the net for a answer to the heat problems for one of my customers cars and I found this post which was VERY Helpful!

At the same time I stumbled upon this post on a different forum today and I think that it is only a few hours old. If they make a combo unit for the GT500 do you think that it would be worth while? It seams to me that when paired with a nice H/E that it would do the trick!

http://www.allfordmustangs.com/forums/mustang-gt500/152111-new-performance-mod-gt500-gt500ss.html

From what I have gathered from web searching and checking out their website, this company "Velocity" Is primarily a Manufacturer and not a retailer. I have found a number of products on different forums from them but none of them are available on their website?!?! Does that sound about right to you?

I also clicked some of the banners on their site and I have seen some of their products private labeled and sold by different companies, so again I think they manufacture for the most part.

What I didn't find was anyone that is a tuner/shop that is carrying these intercoolers or any of the other intercoolers that they have for the 03 cobra. Do you plan on carrying these units? If not, do you know of anyone that is going to be?

Thanks a lot for any additional information that you could provide me with!

Speedemon

[Justin@VMP]

To me, it sounds like snake oil. I have always said that the factory HE is probably not a limitation, a few months back we tested this and did not gain anything from a supposed higher flowing unit. All of the engineers that I know that have data on the OEM HE say its a very good piece that won't be bettered. It would make sense that you can't have both (good cooling and low boost drop), but that you have to trade one for the other or find middleground, which I think the factory piece does pretty well, or go to a bigger unit but there is no room for that.

If you want a mild upgrade to help blower cooling, go with something like an afco HE. If you want a major upgrade, I offer the big C&R dual fan HE.

Here is the testing we did on the in block IC:
http://www.modularfords.com/forums/showthread.php?t=117137&highlight=intercooler

[speedemon138]

I just read the reply on AFM to your comment and it doesnt sound like snake oil to me but I could be wrong. although they did agreed with most of your points on modular fords. I am going to call them today and try and get some more information. If you find out anything before I do, please post it.

Thanks for the quick reply!

Ben

To me, it sounds like snake oil. I have always said that the factory HE is probably not a limitation, a few months back we tested this and did not gain anything from a supposed higher flowing unit. All of the engineers that I know that have data on the OEM HE say its a very good piece that won't be bettered. It would make sense that you can't have both (good cooling and low boost drop), but that you have to trade one for the other or find middleground, which I think the factory piece does pretty well, or go to a bigger unit but there is no room for that.

If you want a mild upgrade to help blower cooling, go with something like an afco HE. If you want a major upgrade, I offer the big C&R dual fan HE.

Here is the testing we did on the in block IC:
http://www.modularfords.com/forums/showthread.php?t=117137&highlight=intercooler

[97WS6m122]

thanks for letting us know your research. I'm doing a custom blower setup and the car is made for road racing so this helps allot.

[Justin@VMP]

Let me know if you need any help with that project.

I have been talking to stephen at VTS and we are going to look into experimenting with some of his ideas, I do think he has some that will help.

[rarnouxp]

Hello Justin, I read thoroughly through your post on the cooling fluid problem and see that you have not posted any conclusions to which solution would work out for road racing application. I run my GT500 on the track twice a month and the fluid overheating is a real pain, I have to basically stop every 10 minutes of hard driving, while other non-supercharged vehicles are still on the race.

You mentioned that changing the HE would not help much, would you have any more recommendations by any chance ?

Tks in advance.

[Justin@VMP]

Hello Justin, I read thoroughly through your post on the cooling fluid problem and see that you have not posted any conclusions to which solution would work out for road racing application. I run my GT500 on the track twice a month and the fluid overheating is a real pain, I have to basically stop every 10 minutes of hard driving, while other non-supercharged vehicles are still on the race.

You mentioned that changing the HE would not help much, would you have any more recommendations by any chance ?

Tks in advance.

I have found dozens of little ways to optimize the system, and there are some new products out there, but the best bang for the buck and what cures 95% of it for most people is a front heat exchanger with a large surface area and fans like the afco dual fan unit I sell:
http://www.vmptuning.com/store/index.php?p=product&id=353&parent=112

[TX STIG]

A couple of questions:

1) You said the tune can allow for the IC pump to kick on at lower temps. Is this automatically done by you when you send out a tune for updated mods (in my case LT headers, high flow cats, and IW 10% lower pulley)?

2) If I remember correctly, the low/high speed fan settings in your tune is set at 204/208 degrees. Would it be beneficial to lower these temps for the hot TX summers? If so, how low should I go?

Thanks!

[Justin@VMP]

A couple of questions:

1) You said the tune can allow for the IC pump to kick on at lower temps. Is this automatically done by you when you send out a tune for updated mods (in my case LT headers, high flow cats, and IW 10% lower pulley)?

2) If I remember correctly, the low/high speed fan settings in your tune is set at 204/208 degrees. Would it be beneficial to lower these temps for the hot TX summers? If so, how low should I go?

Thanks!

Hi,

1) its already set lower of course, it essentially runs all the time, which is good.

2) you do not want to be too close to the thermostat temp or the fan will cycle excessively, i would not change them.

[Whitesnake]

Justin,

what do you think about changing the stock intercooler pump to a much larger/better one plus adding a larger intercooler reservoir? Would this help?

I saw that the 2010 Cobra Jet uses a larger pump. Lethal will sell it as an upgrade to the stock pump.
Here (http://www.who-sells-it.com/images/catalogs/4088/pdf_20980.pdf) is a short overview with other pumps, that can possibly be used.

The stock pump is rated to pump up to 4 GPM, while the larger ones goes up to 55GPM (Cobra Jet).

Markus

[Justin@VMP]

I bought the little johnson pump that claims 8gpm but it only measured 3.5GPM! the stock pump on a GT500 moved 4.5GPM through an aftermarket HE.

I think a bigger pump will help.