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Discussion Starter #1
I decided to wire up some intercooler fans and see how they worked for me. 2007 car.

Installation details:

- Fans are full on or off, controlled by a switch in the cab
- I'm using two puller fans mounted behind the IC
- Specific fans are: SPAL USA

I'm not the fastest or most consistent guy out on track, so when I was thinking about how I might test I didn't think times would be a good measure. Ultimately I decided that since the fans are supposed to help with cooling that the Intake Air Temp would be my best bet as a measure. I'm measuring/logging through OBDII.

I've made one assumption, and that is there is no measurable difference between running the cooler stock and running the cooler with the fans mounted, turned off. I think this is reasonable given the area of the intercooler vs the smallest cross section of the tunnel leading to it. I believe this is going to be at the very front of the rear clam- even if you have a mohawk roof, Lotus didn't change the design of the rear clam so this restriction is in place across all unmodified exige.

The test day conditions were mostly sunny with temps in the low 70's. I was hoping for hotter weather, maybe I'll add that data if the opportunity presents itself. The first graph is the first run of the day, the second graph is the second run of the day, the third graph is the third run. On the first run the temp was 71* and on the third run it was 74*.

In general I'd say its clear that the fans helped lower the IAT, but I can't say that the lowered IAT resulted in keeping up the HP.

Lastly, you can ignore the dip in speed in the middle of the first run. I had to visit the hot pit in the middle of the session because my passenger window was up.


 

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When I read "son of qball" I thought your car had fallen off a lift.
 

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You should also look at the graph with Manifold Pressure (if possible) and or Throttle Position.

Here's my air to water intecooler on my Esprit for example. MAT is intake temp after the intercooler in Deg C. Map is Manifold pressure (ABS) in Bar. This was on a 100deg day btw, though not on track.

 

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Interesting data. It looks like they had significant effect, though I am not sure I fully agree that the fans wont significantly reduce heat transfer when switched off.
 

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Just curious if this with a stock IAT sensor? If so where exactly do they mount that sensor?

In any case the data is pretty cool, no pun intended :) ; the fans do seem to help in your case. Albeit, not a huge change (looks like its about 20* F cooler on average), but every little bit helps!

Edit: I also do think that the addition of fans in an off position isn't the exact same as no fans at all. My gut tells me they impede airflow somewhat, although not to the degree that they help when turned on.
 

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Discussion Starter #8 (Edited)
The stock IAT sensor is located on the 'passenger side' of the IC, so it should be in a pretty ideal spot.

Admittedly if it was reasonable I would have removed the fans completely to keep this point from creeping into the discussion. The fans in a steady state most certainly redirect the air compared to stock, but with the slot being so small I still believe that its akin to a single car encountering a bend in the highway (no real net change in velocity at the speed limit) rather than rush hour traffic encountering a bend in the highway (traffic piles on top of itself and slows down).

Speed ultimately affects this argument though... I'd think that at some higher speed, the fans would become a problem (on OR off). However, the opposite is also true - at lower speeds the fans can most certainly pull more air through than the car sitting still, or moving at low speeds.
 

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It looks like the fans are pulling about 10 degrees out. I wonder how that relates to power.
Interesting that you're hottest during the cool down lap...
 

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It looks like the fans are pulling about 10 degrees out. I wonder how that relates to power.
Interesting that you're hottest during the cool down lap...
Is that really so surprising? I assume the cool down lap is going to be slower than the hot laps, and the rest of the system is heat soaked, so everything will warm up due to less air passing through the radiator.
 

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I would really like to see pictures and get details on how you attached the fans and where you tapped the wires for power. I want to do this because my IAT's get really hot on warm days.

The fans will prevent a small amount of airflow from passing through he intercooler when they are off. It is probably just a small amount though so i doubt you can even measure it. The key is to make sure they are on the back side of the intercooler so they pull air in, this way it lets the most amount of air to naturally pass through.
 

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Discussion Starter #13
As far as the installation goes:

- I mounted a weatherproof relay off the same tab the coolant tank is mounted.
- the GND side of the coil, as well as the GND of the fans, run back to the battery.
- The other end of the coil I routed through the firewall, up the center console to one of the fuse boxes underneath the passenger side. I put an 'add a circuit' on the ignition switched fuse
- I used weatherproof connectors and parts everywhere since the engine bay is more exposed compared to regular cars.

I basically made my own wiring harness that taps into the system at the battery and the fuse box in the cab. No splices, no soldering. For the fans, I mounted them with small metal rods. They look kinda like a really long nail. On the side you see, there is a rubber washer of sorts that helps hold the fan in place. The rods go through the intercooler and on the other side small metal clips keep the rod from pulling out.



I put the switch up here because it seemed to be the safest place from interference. No risk of getting hit with a leg or hand, won't interfere with the shifter, no risk of getting in the way of floor mounted lap harness points.



Here you can see the fans are almost as tall as the IC, but there is plenty of open area on either side, and even in between the fans.
 

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The biggest reductions in spark advance come in before ~160F IAT, so you won't be picking up much power from spark advance until you get below that level... So the gains will be had mainly from cooler intake charge/denser air... Albeit not a lot... As mentioned prior, every bit helps! May consider the side ducts from RLS. They seem to helps as much as anything...

Good tests!

Phil
 

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The biggest reductions in spark advance come in before ~160F IAT, so you won't be picking up much power from spark advance until you get below that level... So the gains will be had mainly from cooler intake charge/denser air... Albeit not a lot... As mentioned prior, every bit helps! May consider the side ducts from RLS. They seem to helps as much as anything...

Good tests!

Phil
I agree, getting the RLS side ducts would be the biggest help but $600+ for a 3 chamber shroud is rediculous! Too bad it had to be made of carbon...
 

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Discussion Starter #16
Yes, you can solve this problem with a few different tactics. One is to increase the speed of airflow over the IC (fans), the other is to increase the volume.

Me! hit the nail on the head. I like the RLS solution, but for $1k I've got time to noodle around ideas of my own. I wish there was a package for cheap bastards like myself... I don't need a carbon fiber version of a part that weighs ounces to begin with.
 

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Agreed with both you guys, though I just ordered the kit from RLS.

I wish there was a plastic version available for substantially less. CF just doesnt make sense for the application.

I thought about drawing one up and then rapid prototyping it in ABS, but then lazyness prevailed
 
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