Cooling Solutions

[Gollum]

You know, there's all this talk on this forum about keeping things cool this, need a large air duct that. I just thought it might be nice to provide some real cold hard facts about solutions that people running high boost can look into. I'll post more detailed information later, so I'll just outline some ideas and other people can chime in with their experience or advice.


1. Water injection - This involves getting a pump to move water from a tank to a nozzle that when forced to flow water at high pressures sprays an ultra fine mist that vaporizes in the blink of an eye in the environment of an engine. This subsequently cools down the air it's sprayed into leaving you a cooler, dense air charge. Retuning is suggested as the intake air temps will be lower and possibly into an area of the tables you haven't refined very well. That said you can get away without retuning if you need to.

2. Meth injection - Almost identical to water injection in application, but adds the benefit of giving your air charge more energy and raising your total octane rating. The only downside is that you need to tune for it as it WILL throw your mixtures off if your tune was solid.

3. IC Sprayers - It's amazing how much this actually helps. Just spray water on your intercooler and watch those temps drop. Just like your body producing sweat, the water on the IC absorbs heat from contact and then as it vaporizes cools the contact surface. The main drawback is that most systems are manually activated which I think is archaic. Ideally you'll hook it up to an output on your ECU of choice and set it to fire off at certain temps so it's automated and tuneable.


There's three big ones to start with. Who wants to go next?

[305mouse]

The STI comes with the IC sprayer. If you bought a wagon as a donor car, you could wire up the rear wiper sprayer to spray the TMIC. You'll want to have a seperate pump in water and not the wiper fluid, even though you could use the wiper fluid. As far as Meth goes, It'll add some punch to the car, you need a tune and would have to have seperate tunes if you decided to run the car without Meth. With Meth your meth/water ratio is usually either 50/50 or 70/30. I think just an IC sprayer would be the most beneficial for the average build. One thing also, is you could use a phenolic spacer which fits between the intake manifold and the heads. Really it's between the TGV's (which should have the butterfly tumblers deleted in my opinion) and the heads. The spacer helps reduce the transfer of heat from the heads to the intake manifold, thus allowing cooler air to enter the engine.

[kach22i]

If you have an air-cooled Porsche there is the "Rubbermaid Solution". Spray water into the cooling fan, primitive but works I'm told.

Link:
http://forums.pelicanparts.com/porsche-911-technical-forum/150982-water-vapor-cooled-911-rubbermaid-solution.html

[riptide motorsport]

Wow,,,,,solutions to problems the don't exist for a car that doesn't exist!/////////Is this what they mean by virtual reality?!.......:)

[kach22i]

We are just guys talking about automotive technology, let your hair down, take your shoes off and feel the grass between your toes riptide. No harm is being done, and no animals were harmed in the making of this film.

I don't think the 818 will be operating outside of the laws of physics, so there is a basis for discussion. Many mid-engined and or rear engined cars face cooling challenges, so this subject is topical.

Premature to be talking about it?

Sure, but in the designer mindset which many of us have (thanks to this competition), we think about these things before they are a problem, so that others don't have to "after the fact".

Thank you for playing, we return you now to our program already in progress.;)

[Flamshackle]

seriously the intercoolers dont require big ugly openings to get loads of air! just good flow and strategic placement of scoops...

water sprayers on the intercooler are a very big aid if done right. few do it right.

meth injection is really going to be only for super high HP chasers and track racers really.

So for 99% of 818 drivers a good stock intercooler combined with an EFFICIENT scoot and a cheap but effective sprayer will keep charged air temps down no probs.

[bromikl]

Silly question for you... Does anyone know the ideal intake temperature?

If it's anywhere around 212F, you could submerge the intercooler. Heat transfer to a liquid is exponentially more efficient than to air. The tank holding the intercooler would need to be vented and have some kind of level control mechanism (i.e. float switch and windshield washer pump). Getting "heat soaked" would be a thing of the past.


The IC sprayer method seems (to me) to be the simplest, and I'm sure it's quite effective enough.

[305mouse]

seriously the intercoolers dont require big ugly openings to get loads of air! just good flow and strategic placement of scoops...

water sprayers on the intercooler are a very big aid if done right. few do it right.

meth injection is really going to be only for super high HP chasers and track racers really.

So for 99% of 818 drivers a good stock intercooler combined with an EFFICIENT scoop and a cheap but effective sprayer will keep charged air temps down no probs.

Very true. You could also go with a larger TMIC, like the STI one or an aftermarket one too. Larger area, better cooling.

[Silvertop]

Are those of us who plan only street use and only moderate engine modifications (say, up to 300 flywheel HP) likely to need to be concerned about Intercooler heatsoak issues?

[StatGSR]

^ wont really know until the car is done, till then we don't really know how much fresh air will be making its way through the engine bay...

[StatGSR]

Silly question for you... Does anyone know the ideal intake temperature?

If it's anywhere around 212F, you could submerge the intercooler. Heat transfer to a liquid is exponentially more efficient than to air. The tank holding the intercooler would need to be vented and have some kind of level control mechanism (i.e. float switch and windshield washer pump). Getting "heat soaked" would be a thing of the past.


a water to air intercooler could certainly be an option, though it will require additional plumbing and an additional heat exchanger (radiator). They can be had for pretty cheap though....

http://www.frozenboost.com/product_info.php?cPath=216&products_id=1034&osCsid=f96605764fd12916e0f91158bd6b5ccb
http://www.frozenboost.com/product_info.php?cPath=216&products_id=1006&osCsid=f96605764fd12916e0f91158bd6b5ccb

other obvious engine heating issues could be solved by changing the thermostat temperature or changing the thermostat location to the top of the engine...

[Silvertop]

^ wont really know until the car is done, till then we don't really know how much fresh air will be making its way through the engine bay...

That occurred to me after I sent the original question. Perhaps I should have phrased it this way: Assuming that the engine bay receives the same level of airflow as a stock WRX, is a mildly modified street version likely to suffer heat soak issues? Or better yet, are sensibly driven street WRX's with mild mods (up to 300 flywheel HP, w/stock turbo) likely to have these issues?

[Gollum]

The biggest problem with heat soak isn't just HP, but time under load. The longer you subject your car to high load, the more likely you'll have heat soak issues.

For example, the Datsun L-gata motor can easily be built to make 500+hp, even over 800 if you feel like just dumping money into the head. And the motor will make the power fairly reliably for being what it is. But, without EXTENSIVE work to the cooling system it won't make that kind of power for extended amounts of time. This is even a problem for the Supra 2JZGTE and the Skylinke GTR RB26DETT. At high HP levels for extended amounts of time, the engine itself heatsoaks and coolant temps rise like a beast.

The lesson in all this is to understand core issues, and what's needed to combat them.

If you're a penny pinching builder that's building the 818 on a shoestring budget then just know that you can't race your car for extended amounts of time without having a hawk's view of temp gauges. The cheapest solution is just some basic IC sprays (done right as flameshackle mentioned) will go a long way in helping heat soak.

Also remember that the largest heat holding device that will be baking your engine bay is the turbo. So a lot of your heat soak issues will arrive from there. Running the stock turbo at stock boost levels will mean the turbo doesn't get too hot. Running the stock turbo at 25+psi the turbo will start getting pretty toasty after 10+ minutes under heavy load. Running the RIGHT turbo for your desired power levels goes a long way in helping keep the turbo at a manageable temperature, as it will be closer to it's peak efficiency, creating less heat per CFM of air. There's also the basic things you can do like heat wrapping, turbo blankets, etc to help keep the heat contained. But heat soak is exactly as it sounds. It's about the time factor it takes for that heat to get through and to start having a cascading effect.

And I'd venture to say that nearly ALL mid engine cars, especially turbocharged ones, have to consider heat soak issues. Weather or not it's a "big deal" is debatable, but it's still something that's on the table as a tuner.

For example: If I was tuning a LS6 in a GTM I'd tune the motor to get a bit rich past normal operating temp, and have it getting nearly pig rich upon what would be considered dangerously hot. Running rich has a cooling effect on the motor and will help cool it down in the event that the engine starts heat soaking on the track. Yes it'll make less power, but the engine's longevity is more important to most. If I was tuning the same engine in a Vette, then I'd be much more aggressive with the temperature tables waiting until the very last moment of temperature to run it rich, because I know the engine is much easier to cool off once it's gotten to those temps.

[Mike Downs]

The biggest problem with heat soak isn't just HP, but time under load. The longer you subject your car to high load, the more likely you'll have heat soak issues.

For example, the Datsun L-gata motor can easily be built to make 500+hp, even over 800 if you feel like just dumping money into the head. And the motor will make the power fairly reliably for being what it is. But, without EXTENSIVE work to the cooling system it won't make that kind of power for extended amounts of time. This is even a problem for the Supra 2JZGTE and the Skylinke GTR RB26DETT. At high HP levels for extended amounts of time, the engine itself heatsoaks and coolant temps rise like a beast.

The lesson in all this is to understand core issues, and what's needed to combat them.

If you're a penny pinching builder that's building the 818 on a shoestring budget then just know that you can't race your car for extended amounts of time without having a hawk's view of temp gauges. The cheapest solution is just some basic IC sprays (done right as flameshackle mentioned) will go a long way in helping heat soak.

Also remember that the largest heat holding device that will be baking your engine bay is the turbo. So a lot of your heat soak issues will arrive from there. Running the stock turbo at stock boost levels will mean the turbo doesn't get too hot. Running the stock turbo at 25+psi the turbo will start getting pretty toasty after 10+ minutes under heavy load. Running the RIGHT turbo for your desired power levels goes a long way in helping keep the turbo at a manageable temperature, as it will be closer to it's peak efficiency, creating less heat per CFM of air. There's also the basic things you can do like heat wrapping, turbo blankets, etc to help keep the heat contained. But heat soak is exactly as it sounds. It's about the time factor it takes for that heat to get through and to start having a cascading effect.

And I'd venture to say that nearly ALL mid engine cars, especially turbocharged ones, have to consider heat soak issues. Weather or not it's a "big deal" is debatable, but it's still something that's on the table as a tuner.

For example: If I was tuning a LS6 in a GTM I'd tune the motor to get a bit rich past normal operating temp, and have it getting nearly pig rich upon what would be considered dangerously hot. Running rich has a cooling effect on the motor and will help cool it down in the event that the engine starts heat soaking on the track. Yes it'll make less power, but the engine's longevity is more important to most. If I was tuning the same engine in a Vette, then I'd be much more aggressive with the temperature tables waiting until the very last moment of temperature to run it rich, because I know the engine is much easier to cool off once it's gotten to those temps.

I have a stock LS6 in a GTM and I have seen 235 degrees in traffic or coming off the track and waiting in line to get back to my pit space. The engine temperature will get down fairly quickly if driven at any speed over say 30 mph. So, a larger radiator isn't the issue (I also know that I can reprogram the PCM to turn on the radiator fans at lower temperatures). My point here is that running the engine rich under higher RPM/higher loads won't help the problem. It is the fact that when the car is moving very slowly or not at all, heat WILL build up in the engine compartment. In a front engine car, the radiator fans will move some air through the engine compartment to help reduce those temperatures. I plan on adding a couple of 6" fans and exhausting air from the engine compartment into the rear wheel wells. Bottom line is that you have to get some air movement in the engine compartment even when the vehicle is standing still.

[Silvertop]

Now there's a MAJOR bunch of useful information in those last couple of posts. -- Thanks gents.

[Gollum]

I have a stock LS6 in a GTM and I have seen 235 degrees in traffic or coming off the track and waiting in line to get back to my pit space. The engine temperature will get down fairly quickly if driven at any speed over say 30 mph. So, a larger radiator isn't the issue (I also know that I can reprogram the PCM to turn on the radiator fans at lower temperatures). My point here is that running the engine rich under higher RPM/higher loads won't help the problem. It is the fact that when the car is moving very slowly or not at all, heat WILL build up in the engine compartment. In a front engine car, the radiator fans will move some air through the engine compartment to help reduce those temperatures. I plan on adding a couple of 6" fans and exhausting air from the engine compartment into the rear wheel wells. Bottom line is that you have to get some air movement in the engine compartment even when the vehicle is standing still.

Umm. I didn't say tune it rich in high rpm/load, I'm talking about running the temperature adjustment table less aggressively so that when the engine is hot you're running richer, thus helping stabilize temps. As you stated, more airflow at low speeds can definitely help traffic conditions.

But most PCM/ECUS are whatever you want to call your engine management, have temperature adjustment values, usually one for coolant/engine temp, and one for air temp. You use these tables as a major source for warm up enrichment, and in theory the table goes away once under normal temps. But you can also use these tables to ADD fuel when temps go beyond normal. Some ECU's do this from factory, others don't. But I've seen painful results from someone that doesn't take the time to adjust these tables correctly, and end up blowing up a motor because there wasn't enough fuel added in after the engine started to get overly warm.

If you're going for every last pony, you force the engine under load on a brake dyno to get hot and you find your "rich best torque" under those extreme conditions to minimize power loss under heavy load on a hot track day. But I'm saying that if I were tuning a mid engine vehicle, I'd be more conservative than "rich best toruqe" on those conditions and be shooting for a good .3-.5 AFR lower than rich best torque for a given RPM for that engine.

Tuning your base RPM/Load tables is an entirely different matter and should always reflect getting the most power you can. I'd never tune the main table rich on purpose for cooling an engine, that's just retarded.

[305mouse]

That occurred to me after I sent the original question. Perhaps I should have phrased it this way: Assuming that the engine bay receives the same level of airflow as a stock WRX, is a mildly modified street version likely to suffer heat soak issues? Or better yet, are sensibly driven street WRX's with mild mods (up to 300 flywheel HP, w/stock turbo) likely to have these issues?

All things being equal, you can leave everything OEM and be fine. The 02-05 WRX made 227 at the flywheel, so if you're looking to gain another 70 hp, I would consider a larger TMIC. Heat soak is always a concern in city traffic. For a fun DD, if I lived in AZ, NV or someplace like that, I would invest in a sprayer on a larger TMIC. I wouldn't suggest that for a DD up north unless it pulled double duty at a track. I will say, the way the 818 is planned out, unlike a WRX, there will be some room in the engine bay. It could be possible to make a heat shield to go between the block and the TMIC. It wouldn't block all of it, but it would help. Something else to remember, the turbo is just the the side and below the TMIC as well.

[Steve91T]

The MR2 turbo had heat soak issues due to the intercooler having fairly poor airflow, and it was located near the turbo down pipe. I had a simple, digital intake temp gauge, with the sender mounted in the throttle body. While I can't really remember the numbers, I do remember watching the temps climb quickly during acceleration (12 psi), then hanging as I let off. They would then slowly drop. After sitting in traffic, heat soaking would cause the temps to climb quickly, then hang at that high temp for a long time, before slowly dropping.

I then hooked up a very simple sprayer using a 1 gal fuel tank, a cheap washer fluid motor, some hose, and a garden mister sprayer. I had it wired up to an adjustable boost pressure switch that would activate the sprayer. I could also spray it any time I wanted with a separate button. It worked really well. With the sprayer armed, the intake temps would climb during acceleration, but then immediately start to cool. I could not get it to heat soak, no matter now much hot, city driving I did.

While I don't think the 818 is going to need a sprayer, it is very effective and inexpensive. Using the pressure switch was very easy. Just plug it into any vacuum hose. I had a master switch to arm the system, an override button, and two LED's. One when it was spraying on it's own, and one when I pushed the button. I spent $50 tops.

Hope this helps.
Steve

BTW, I believe turbo's heat the air to about 250 degrees F. The air/air intercooler should get the intake temps down to something like 20 degrees above ambient.
Air/water are very effective, but more expensive, more complicated, and heavier.

[Admiral Doom]

If you wanted to get into something a little more interesting, look into something us Mustang guys call the "Killer Chiller". It uses the A/C system (compressor, condenser, etc) and the evaporator as an intercooler, sort of like an "Air-to-R134" intercooler. Would be a good use of the Subie a/c system, seeing as a/c is pointless in a topless roadster. Plus, it doesn't need to be refilled like a water sprayer. Just something to think about.

[thebeerbaron]

If you wanted to get into something a little more interesting, look into something us Mustang guys call the "Killer Chiller". It uses the A/C system (compressor, condenser, etc) and the evaporator as an intercooler, sort of like an "Air-to-R134" intercooler. Would be a good use of the Subie a/c system, seeing as a/c is pointless in a topless roadster. Plus, it doesn't need to be refilled like a water sprayer. Just something to think about.

From the Killer Chiller FAQ (http://www.killerchiller.com/faq.htm), this system cuts out in boost. So if you stay in boost for any length of time, you will exceed the available cooling. Probably good for 1/4 mile and the street, but not sure about true track applications. They say people use it on the track, but...

The real solution is a properly-sized intercooler receiving proper airflow.

To throw a wrench in the works - how much are you willing to sacrifice the aesthetics of the body design in order to have a happy intercooler?

Exige, with the roof-mounted intake and no rearward visibility?

911, with some crazy setup in the tail?

Put it another way - how much are you willing to sacrifice in terms of charge plumbing length? The stock Subaru takes full advantage of the flat boxer motor and has an astoundingly short stretch of charge piping - off-the-cuff guess is 18-24" from turbo outlet to throttle plate. This has ramifications in terms of boost response (not "spool"), etc. Sacrifice this killer advantage to put the intercooler in a side scoop?

Just wondering what people think...

[bromikl]

In an earlier thread there was some discussion about where to place the radiator. In the 818 the main radiator will be in the front center. The IC will remain in the rear, and I'm sure they are analyzing the airflow issue.

For most folks it seems the IC sprayer will be effective enough - if needed at all. If one were to have an engine that requires an air-to-water intercooler, I'll bet he also has the skill to put together a custom setup - which might even be preferable. In that case, there are several alternate radiator locations in the rear. Many of the designs include functional side scoops - not the decorative ones you see on many muscle cars.

The idea I floated earlier isn't the best, but it would ensure intake temp never gets above 212F. The IC would basically boil away enough water to keep that temp. It might even make tuning simpler, as it will also raise intake temp when not under boost. No quick changes at different RPMs or boost pressures.

[EmergencyDeep]

Bromikl,
A submerged IC will ensure the _intercooler_ does not exceed 212F, however it does not guaranteed that the _air to the engine_ will be less than 212. It is a heat transfer issue, not purely a temperature issue.

[bromikl]

Bromikl,
A submerged IC will ensure the _intercooler_ does not exceed 212F, however it does not guaranteed that the _air to the engine_ will be less than 212. It is a heat transfer issue, not purely a temperature issue.

Good point. 212F seems too high, anyway.

[StatGSR]

I'm getting really confused about all this "submerged" talk

sounds like your talking about a liquid heat sink and not a proper air to water/water to air heat exchanger system...

if that's the case, its a horrible idea...

[Steve91T]

I don't get it either. I think the person who posted the submerged IC talk doesn't know about an air/water IC.

Beer, I don't think the length of IC plumbing honestly makes that much of a difference in throttle response. If you were going to do a front mount IC, then yeah, 20 ft of plumbing would make a difference. MR2 guys mount theirs in the trunk to support a huge intercooler. I would personally want as much cold air to that IC as possible, which is probably going to require mounting it somewhere else.

http://www.mr2beast.com/tmic.htm

[kach22i]

The Beast.............that was a nice car man.

[GS guy]

The key is really going to be finding the high and low pressure zones around the back of the car while moving. Adding in fans, sprayers, or another entire cooling system (for an air-water IC) adds a lot more to the build complexity! A passive air-flow system might not provide the best IC cooling 100% of the time (like sitting in traffic), but sure has less parts to buy, figure out how/where to install and possibly fail at some point.
Using the naturally available pressure zones is key to getting good air flow through the air-air IC. In a mid-engine car this is especially tricky.
I would imagine Dave and crew are taking careful consideration of all this in their design - or at least keeping it in mind as the prototype develops!

Kind of a catch-22 really. You need a running vehicle (or sophisticated wind tunnel and carefully constructed model) to figure out the high and low pressure zones, so you don't really know where/how to situate the air intakes and IC exhaust until the car is running and driving - which means the IC cooling might be pretty crappy when the first prototype hits the road!

Even the mighty GT40 from the 1960's had similar problems - when someone noticed air was flowing out one of the side air intake ducts going down the road!

[bromikl]

Using the naturally available pressure zones is key to getting good air flow through the air-air IC. In a mid-engine car this is especially tricky.
I would imagine Dave and crew are taking careful consideration of all this in their design - or at least keeping it in mind as the prototype develops!

FFR is "working closely with" SolidWorks, who has the ability to model airflow before a single car is built. I understand computer models aren't perfect, but these days they can get awfully close:

Check out the NASCAR drafting simulation
http://www.solidworks.com/sw/products/cfd-flow-analysis-software.htm

Props from Burt Rutan, the world renown aircraft designer
http://www.solidworks.com/sw/news/245_article2004_1_ENU_HTML.htm?fromrss=1

[Niburu]

imma laugh when this car has no cooling issues................hopefully

[Gollum]

imma laugh when this car has no cooling issues................hopefully

Well then I'll just be turning up the boost more! :cool:

[Inthenameofweez]

I'd really like to see FFR use the Process West Top Mount Intercooler for mock up when building the Race Version of this vehicle. A factory intercooler has been ditched on almost every modified WRX for a reason. The intake needs to be able to be modified to fit a larger intercooler. And more to the point, the intake needs to SEAL on the intercooler with a foam or rubber piece to prevent air simply hitting the top and passing over. Air must be forced through. If you need parts, I'm willing to take my WRX apart and send them to you!!! Lol.