TMIC fan with controller setup

[dahoseman]

So ..... this is based purely on conjecture and untested/unscientific personal experience with various cooling fin setups in various situations .....

 

With the car driving at any reasonable speed, I think that the specific type of TMIC would make a much greater difference in heat transfer than whether or not a fan was underneath. In other words, I think your type of intercooler will determine how fast you pass the truck up the hill much more than whether or not a fan sits behind it.

 

With the car sitting at a stop light, I think that the fan would make a much greater difference in how the car accelerates off the line and whether it has any power in traffic. In other words, I think that the fan will perform better in most traffic situations.

 

I actually suspect that a bigger and better intercooler that absorbs/transmits heat more readily might show a decrease in performance in hot city stop-and-go. I definitely noticed an increase in hesitation and knock incidents when I swapped to a process west style setup. I was confused until I investigated our turbo and hood scoop design and realized that heat from the turbo travels up, tries to escape and displace cooler air, and runs convection through the fins to the scoop. In other words, the better your intercooler is at transferring heat, the better it is at also absorbing turbo-heat escaping upward through the intercooler. The overall design is not awful, but they really should have created a specific divider or chimney for turbo heat. In fact, they could have even designed a flume to allow the escaping turbo heat to create a vacuum/convection to pull air through the scoop when sitting in traffic, very similar to how certain furnaces use energy of rising and escaping furnace gases to pull air and cool outside knobs and handles

......... hmmmmm ...... that actually could be an interesting project for our cars. Now my wheels are turning.

 

I used to build fun computer cooling setups as a kid. One thing I came to realize the hard way is that cooling really is physics, and yet, is pretty simple. I found that certain structural fin designs made a huge improvement in heat dissipation. I also found that certain metals make a huge difference (beyond simple 3D structure) in transferring heat. The biggest overall lesson that I learned was that airflow (or water or oil cooling flow) really trumps them all. The most impressive cooling heat sink will get completely outperformed and dominated in a stagnant case by a cheap/crappy heat sink if the incoming air is not piped correctly or ...... especially if the cooling fan is a "dud" while the cheap/crappy heat sink has a good fan moving air. The difference in size of fan or fan speed was noticeable, but nowhere near the difference between fan/no-fan.

 

Having said all of this, we can argue until we are blue in the face about what we THINK will happen. There is only one real way to know for sure. Build a setup, do a few experiments, tweak it to work out the kinks, do a few more experiments, and then report data. If it has positive results, fantastic. If the results are negative or negligible, then that is also something of value and we have all learned something and can now speak more intelligently on the subject in the future with real results.

[fotofan]

No but with a fixed blade fan, making it stop in place creates more drag. If the fan is allowed to windmill, it's robbing the moving air of less movement, or pressure. As I said, the airplane analogy is incomplete. A feathered prop has no force causing it to windmill, if it weren't feathered it would try to windmill which would create more drag. I'm not arguing that a windmilling fixed-blade prop/fan creates drag, but it does create less drag than a completely stopped fixed-blade.

[Silinc3r]

Well I was looking for cheap airflow meters but they are not cheap. Also in real world conditions it will be very hard to do. I have looked at different intercooler testing but of course it is all about pressure and heat inside.

I went ahead and bought a dual air temp gauge from glowshift, cheapest I could find and they have decent stuff. I know what the heat is inside the intercooler but the heat underneath is much hotter.

I used the other temp sensor from DEFI triple pack and placed it on the back side. Driving around at 60 MPH with 75F day it was about 150-170F. As soon as I start to slow to a stop it would pick up rather quickly. When I got home, I sat there with the car on to try and see what the peak temp was. It was at about 300F! At this temp, IAT was at about 115F and TMIC would heatsoak at 140F.

I know we keep bring up airflow but I really think all I need to test is temp differences. If it rises with it installed, we know we have a blockage. If it is kept spinning/stopped and the temp rises at say a higher speed, we know we have a blockage. I think this will be sufficient enough DATA to conclude if it is working or not. The difference of the temps though with and without fan will be the deciding factor.

 

Also, I fly on rotary wing so no stalling props for us.

 

utc_pyro, thanks for the info on the radiator. That might just be the info we need. That has the most direct airflow, a set range that it has to stay in and fans that operate at highway speeds if the temp rises to high. Most of the time on the highway the coolant temp will stay at that 185-190F range so the fans would be off. If the Subaru engineers though the fans were going to block too much flow they would have them on all the time, I would imagine.

 

Also thinking about it. The rad or intercooler has to pretty much bring the air to a very reduced speed. If it went through it at the same speed it went in, there would be much cooling. If heat transfer was that quick, rads and intercoolers wouldn't need to be so large, right?

[Silinc3r]

So ..... this is based purely on conjecture and untested/unscientific personal experience with various cooling fin setups in various situations .....

 

With the car driving at any reasonable speed, I think that the specific type of TMIC would make a much greater difference in heat transfer than whether or not a fan was underneath. In other words, I think your type of intercooler will determine how fast you pass the truck up the hill much more than whether or not a fan sits behind it.

 

With the car sitting at a stop light, I think that the fan would make a much greater difference in how the car accelerates off the line and whether it has any power in traffic. In other words, I think that the fan will perform better in most traffic situations.

 

I actually suspect that a bigger and better intercooler that absorbs/transmits heat more readily might show a decrease in performance in hot city stop-and-go. I definitely noticed an increase in hesitation and knock incidents when I swapped to a process west style setup. I was confused until I investigated our turbo and hood scoop design and realized that heat from the turbo travels up, tries to escape and displace cooler air, and runs convection through the fins to the scoop. In other words, the better your intercooler is at transferring heat, the better it is at also absorbing turbo-heat escaping upward through the intercooler. The overall design is not awful, but they really should have created a specific divider or chimney for turbo heat. In fact, they could have even designed a flume to allow the escaping turbo heat to create a vacuum/convection to pull air through the scoop when sitting in traffic, very similar to how certain furnaces use energy of rising and escaping furnace gases to pull air and cool outside knobs and handles

......... hmmmmm ...... that actually could be an interesting project for our cars. Now my wheels are turning.

 

I used to build fun computer cooling setups as a kid. One thing I came to realize the hard way is that cooling really is physics, and yet, is pretty simple. I found that certain structural fin designs made a huge improvement in heat dissipation. I also found that certain metals make a huge difference (beyond simple 3D structure) in transferring heat. The biggest overall lesson that I learned was that airflow (or water or oil cooling flow) really trumps them all. The most impressive cooling heat sink will get completely outperformed and dominated in a stagnant case by a cheap/crappy heat sink if the incoming air is not piped correctly or ...... especially if the cooling fan is a "dud" while the cheap/crappy heat sink has a good fan moving air. The difference in size of fan or fan speed was noticeable, but nowhere near the difference between fan/no-fan.

 

Having said all of this, we can argue until we are blue in the face about what we THINK will happen. There is only one real way to know for sure. Build a setup, do a few experiments, tweak it to work out the kinks, do a few more experiments, and then report data. If it has positive results, fantastic. If the results are negative or negligible, then that is also something of value and we have all learned something and can now speak more intelligently on the subject in the future with real results.

 

You didn't read from the beginning did you?

 

A larger TMIC, say the PW/AVO/Perrin or GS will take longer to heatsoak and will hold it longer. This has been discussed and is the main reason I have not switched. Will they make more power? Of course they will if you are over a certain level. It also may have a higher heatsoak temp vs our smaller plastic TMIC. Also, did you ditch your heat shielding. That will also play a roll. And yes heat rises, doesn't matter what the setup is.

The early, aka 1st gen Legacy came with a chimney as factory. However, the 1st gen wasn't intercoolerd in the states.

[solidxsnake]

Also thinking about it. The rad or intercooler has to pretty much bring the air to a very reduced speed. If it went through it at the same speed it went in, there would be much cooling. If heat transfer was that quick, rads and intercoolers wouldn't need to be so large, right?

 

This isn't true. More flow (i.e. faster air velocity) will give you more cooling. There is obviously a point of diminishing returns (and this point may be lower than most would expect), but really slow moving air will not cool as well as faster moving air. Heat transfer rates correlate directly to temperature gradients. From this, if you moved air slowly through the intercooler, the air would heat up more, meaning that it would pull less heat from the intercooler as it moved through. Again... this is probably not a big deal because extra flow hits a point of diminishing returns pretty quickly.

 

The reason rads/intercoolers/etc are so large is purely due to surface area. That's also why they use fins. Fluid heat exchangers that have higher heat transfer capability will use more densely packed fins than those with lower capabilities, but the caveat there is you need to increase the flow rate through them to reap the benefits. The other tradeoff is that a larger cooler generally means more mass, which generally leads to more thermal capacitance (harder to heatsoak, but harder to cool after being heatsoaked, etc.). Nothing you don't already know

[Silinc3r]

Yea I guess that was kind of dumb haha. Now, if we drove at a constant speed then maybe they could be reduced in size. Also if what I was thinking was true, then driving slow wouldn't be much of an issue because more time would be spent. Maybe I was think of surface area. The more surface area the more air it touches, less area more air is needed, things being constant.

 

I am going to try and pick up a Dwyer Magnehelic to try and messure the pressure differences.

 

Thanks again to utc_pyro for pointing me toward that Autospeed forum. I have ran across some of their stuff here and there before.

[utc_pyro]

I am going to try and pick up a Dwyer Magnehelic to try and messure the pressure differences.

 

Thanks again to utc_pyro for pointing me toward that Autospeed forum. I have ran across some of their stuff here and there before.

 

I may have one you can just have , let me go check storage.

[Silinc3r]

I may have one you can just have , let me go check storage.

 

 

I just bought one ahah

[Silinc3r]

Fan came in yesterday. Took it on drive to test fan movement. About 20mph is when the fan starts to rotate. I have it to connected to the bottom of the TMIC now and tonight will test again to see the speed it takes to make it rotate. I also will have a video up showing the quick test fit with operation.

Going to try and see if I can make a shroud tonight at work and go from there.

[Silinc3r]

TMIC fan set up, test fit

[boxkita]

You didn't read from the beginning did you?

 

A larger TMIC, say the PW/AVO/Perrin or GS will take longer to heatsoak and will hold it longer. This has been discussed and is the main reason I have not switched. Will they make more power? Of course they will if you are over a certain level. It also may have a higher heatsoak temp vs our smaller plastic TMIC. Also, did you ditch your heat shielding. That will also play a roll. And yes heat rises, doesn't matter what the setup is.

The early, aka 1st gen Legacy came with a chimney as factory. However, the 1st gen wasn't intercoolerd in the states.

 

Back in the day,er, when I installed the PWIC in my wagon. I was worried about heat-soak after we learned a 5lb bag of ice sitting on the intercooler with a dedicated high speed fan was the only way to get a good reading on the dyno.

 

On the autox track, even the hot days it didn't heat soak until late afternoon. Then I'd put the 5lb bag of ice between runs.

 

The rest of the time, I never had an issue. However, I never spent much time idling in traffic. Also, the PW system seals the scoop to the tmic so there's no other path for the air to take.

[dahoseman]

TMIC fan set up, test fit

 

 

Do you mind recording some intake air temps in different driving and traffic situation before and then after the fan?

 

As far as the shroud goes, my old Toyota van had a shroud with thin rubber flaps down the sides and in the corners. The fan suction "sucked" the flaps closed in stop-n-go traffic. When driving speed exceeded fan speed or built up any pressure, it it would push out the flaps to allow air to bypass the fans. Just a thought

[utc_pyro]

As far as the shroud goes, my old Toyota van had a shroud with thin rubber flaps down the sides and in the corners. The fan suction "sucked" the flaps closed in stop-n-go traffic. When driving speed exceeded fan speed or built up any pressure, it it would push out the flaps to allow air to bypass the fans. Just a thought

 

That's a great idea actually. If OP makes as all plenum behind the IC, he can use rubber flaps in the corners. If the fan being on can't keep up at speed they'd open and release some of the pressure.

 

Not that that'll probably happen at any legal speed. We'll know more when OP gets his Manometer in and we see the actual pressures.

[Silinc3r]

Do you mind recording some intake air temps in different driving and traffic situation before and then after the fan?

 

As far as the shroud goes, my old Toyota van had a shroud with thin rubber flaps down the sides and in the corners. The fan suction "sucked" the flaps closed in stop-n-go traffic. When driving speed exceeded fan speed or built up any pressure, it it would push out the flaps to allow air to bypass the fans. Just a thought

 

Intake temps don't matter here. Yes I can monitor but it is the Intercooler temps I am looking at.

 

Got my dual air temp guage from Glowshift but the probe is not what I was hoping for. The threaded portion is quite big. I'll see what I can do though.

[fotofan]

Yeah but the temps are directly related. Comparison monitoring of your IAT before and after will be just as useful as intercooler temps, and IMO the IAT is really what you need to look at.

[solidxsnake]

Yeah but the temps are directly related. Comparison monitoring of your IAT before and after will be just as useful as intercooler temps, and IMO the IAT is really what you need to look at.

 

IAT tells nothing about the result of the fan/no-fan thing, since it's done at the MAF. He's already planning on monitoring pre-/post-IC temps, so the actual intake charge temp going into the manifold is covered.

 

That said, I wouldn't say "intake temps don't matter." Yes, you can get a reasonable measurement of the delta from looking at pre/post IC temps, but monitoring intake temps (or better yet, ambient temp near the hood scoop with an independent thermocouple/thermistor) will give you a good idea of how ambient temps are affecting the IC's efficiency. A colder ambient temp will give you a larger delta between the in/out of the IC, since it will produce a larger gradient between the hot intake charge and the air flowing through the fins.

[fotofan]

Oh. Yeah. D'oh!

[Silinc3r]

I haven't forgot about this I swear!!!

 

Finally was able to finish the shroud up. It is a little crude and I have some finishing details to do but for the most part it's done.

 

It makes pretty good suction when I leave the TMIC on the table. I can't wait to start doing some more testing. I am not sure when that will be. Hopefully soon as I have school coming up.

[solidxsnake]

Looks great! Can't wait to see your data

[WRX USA]

http://page5.auctions.yahoo.co.jp/jp/auction/e188720985

 

One for sale in Japan.

[dahoseman]

That's a great idea actually. If OP makes as all plenum behind the IC, he can use rubber flaps in the corners. If the fan being on can't keep up at speed they'd open and release some of the pressure.

 

Not that that'll probably happen at any legal speed. We'll know more when OP gets his Manometer in and we see the actual pressures.

 

The rubber flaps seemed to work pretty well on those vans, for their intended purpose. The fans on those vehicles didn't move a hell of a lot of air, so those flaps were pretty critical to make sure all the air was coming through the radiator in slow traffic. Essentially they were like a mudflap sitting on a grate. When some air got ducted in across the radiator and outflowed the crappy fan, air would just bypass the fan and push out through the flaps.

 

Those vans had in interesting mechanical clutches that worked pretty similar to the viscous diffs we have. Essentially, when the water circulating around the fan clutch reached a specific temp, a non newtonian fluid between plates would become highly viscous and turn the fan until the water temp decreased to the point that the clutch would lose viscosity.

[fotofan]

Off-topic but that's how pretty much all fan clutches work, which of course only longitudinal engines use fan clutches.

[turbo2]

Unplug your window sprayers and point them at the intercooler. Re connect when done with track day.

[Silinc3r]

Alright back in it, to win it.

 

So, finally got everything installed for my mini build and went ahead and installed the fan. I currently have no heat shield on the turbo, just the blanket. Temps have only been about 4* F over ambient driving normal and I contribute that to the missing heat shield.

Currently, I can not drive it hard as my AFRs are a bit high when in boost so I need to log and maybe get retuned. Also, the fan isn't running during driving right now. This weekend hopefully I'll be able to get it wired up. So far though, it doesn't show a significant increase in temps driving 60 mph and below. I'll have to take another look once I install the heat shield to see if it drops again and then with the fan running.

 

Still no hard evidence, save for actuall pre and post intercooler temps.

[JmP6889928]

I think I would build a plenum under the TMIC and mount a squirrel cage type of fan in the plenum and pull the air through the TMIC. That's how it's actually designed with the undertray creating a low pressure center underneath the car to help actually pull air in through the scoop. The scoop would actually be more effective if turned around the other way utilizing the cowl of the car as a low pressure (eddy current) area but it probably wouldn't look as cool.