Thinking of getting new cooling fans

[Zolli]

Does anybody know the CFM of the two radiator fans? Or at least some way to figure it out?

I have the front end off to swap out a scurvy helicog accessory belt, and I'm eyeing those two fans thinking maybe I can do better. I was looking at Flex-a-lite's wavy-blade fan and Mishimotos. Ideally I'd simply remove the existing ones (by Nissens?) and swap in the new bad boys, but I guess we'll see about mounting points.

I'm also assuming these are 12-volt fans and don't utilize a transformer to kick it up to 24V. The parts catalogue says these are 400W and 300W fans, which suggests 33 Amps and 25 Amp fans, which strikes me as huge - like maybe I'm looking at it incorrectly. And I don't know how to convert Watts to CFM for fans.

Thoughts and ideas? Thanks guys

[Zolli]

Alrighty, I got some research done.

For the calculations, we have to make some assumptions. The first assumption is that you can’t lie on the internet. So all stated CFM values and amperages from manufacturers are assumed accurate. Second, that all fan CFM values are for 0 static pressure, which we know won’t be the real world because we want to stick a big ass radiator (or two) in front of it). Third, that all of this is happening at Sea Level, or 1.0 atmospheres.

Audi provides only the Wattages for the two fans: 300W for the 12” fan and 400W for the 16” fan.

The internet / sciencey stuff provides the following formula:

1 Watt = 0.021 atm cfm (atmosphere • cubic feet per minute)

1 atmosphere = 14.7 psi (sorry to all you Metric people using Pascals)

For Audi’s 12” fan: 300W / 0.021 / 14.7 = 972 CFM. This is similar to other medium-performance 12” fan specs.

For Audi’s 16” fan: 400W / 0.021 / 14.7 = 1296 CFM. Also similar to other medium-performance fan specs.

The two fans combine for a total of 2268 CFM. Is that adequate for our 4.2L V8s?

Flex-a-lite recommends 2800 CFM minimum for a 302 ci V8. The Audi V8’s displacement is 4163ccm, which translates to 254 cubic inches.

Using the same ratio for the 302, the 254 should reasonably have 2355 CFM minimum. The two stock fans provide about 70 CFM less than that, which is about 96% of the Flex-a-Lite recommended amount. That’s pretty good, but it may also explain some of the heat issues we find in the engine bay. Sure, Flex-a-Lite is in the business of selling fans, but I think they know that if they aren’t accurate enough about their recommendations, then they won’t be taken seriously.

Next I was thinking about current draw. In the original post, I forgot that the running Volts is roughly 14 Volts, so I should divide the Wattage numbers by 14, not 12. Because Watts = Amps • Volts.

For the 12” 300W fan, the current draw is 21.4 Amps

For the 16” 400W fan, the current draw is 28.6 Amps

The total then is 50.0 Amps for the stock system. That’s probably reasonable for 15-year-old technology.

For the stock system, you get about 47.1 CFM/Amp. That’s our baseline for efficiency.

Next I compared 16” and 12” universal-style puller fan combos from three aftermarket manufacturers: Flex-a-Lite, SPAL, and Derale. I dropped Mishimoto from the analysis because they got pretty poor ratings on their universal fans. I also got the prices for each fan combo so I could further compare the value of each combo. I used a unit of “E” (efficiency, or CFM per Amp) per $ for that. It’s super totally official. Look it up.

I compared the Derale Tornado fans, the Flex-a-Lite’s new Flex-wave fans, and SPAL’s normally great fans.

Summit Racing was the only retailer I could find that carried all six fans, so I used their pricing. They were usually the best price, but not always. The difference maybe added up to $20 so I didn’t worry too hard about it. I only stayed up and chewed my fingernails for two nights.

Results in no particular order:

Derale Tornado 12” and 16” fans, numbers 16512 and 16516 respectively. $215 for the set.
Total 3055 CFM at 27.2 Amps, for 112.3 E and 0.52 E/$.
Compared to stock, this represents +700 CFM (+30%) and 22.8 fewer amps (54% of stock).

SPAL 12” and 16” fans, numbers 30101522 and 30102049 respectively. $247 for the set. Note some Derale fans are apparently made by SPAL.
Total 3352 CFM at 31 Amps, for 108.1 E and 0.44 E/$. Compared to stock, this represents +1100 CFM (+47%) and 19 fewer amps (62% of stock).

Now we come to Flex-a-Lite’s new Flex-wave fans, which use a fancy blade profile to increase CFM and decrease noise. They probably use brushless motors, but they don’t say. I’m going to assume these numbers are correct, even though they’re way higher. See for yourself and decide.

Flex-wave 12” and 16” fans, numbers 116542 and 116544 respectively. $232 for the set.
Total 3985 CFM at 19 Amps (I wonder if this is a typo on their product page for the 16” fan: maybe it should be 21 amps instead of 11 amps), for 209.7 E and 0.90 E/$.
If the 16” fan is indeed actually 21 amps, that’s still a huge 137.4 E and 0.59 E/$.
Compared to stock, this represents +1630 CFM (+69%) and 31 fewer amps (or maybe 21 fewer if there’s a typo) (38% or 58% of stock).

Realistically, all of these fans promise to be a marked improvement over stock. It’s like adding a third fan. I haven’t compared mounting points between the aftermarket and the OE fans, but I’m guessing some fit-work will be necessary no matter what. I did, however, make sure that none of the fans were thicker than 3.625” so they’d clear the front of the engine.

Considering the cost is nearly the same across all these brands, I’m going to take the chance on the Flex-waves. Even if *gasp* something claimed in marketing on the internet ISN’T true, I can be fairly confident that I’ll still be increasing my CFM beyond stock levels.

[Pnflds]

This is very interesting, if those numbers are ALL truly accurate. I'll be following your progress.

[Zolli]

Update:

Yep, some “clearancing” (to use some JHM jargon) was indeed required. The mounting points weren’t even close. The wires need some re-routing. And the stock 16” fan is actually closer to 15”. Must be a metric thing. But they fit.

But WOW the Flex-Waves really move some air! The stock Valeos were pretty paltry in comparison. The Flex-Waves felt like 2x-3x the blast.

I worked up a little low-amp test; I’ll post results soon. It was all highly scientific including a cardboard box and orange tape.

[Atomic Avant]

Update:

Yep, some “clearancing” (to use some JHM jargon) was indeed required. The mounting points weren’t even close. The wires need some re-routing. And the stock 16” fan is actually closer to 15”. Must be a metric thing. But they fit.

But WOW the Flex-Waves really move some air! The stock Valeos were pretty paltry in comparison. The Flex-Waves felt like 2x-3x the blast.

I worked up a little low-amp test; I’ll post results soon. It was all highly scientific including a cardboard box and orange tape.

Very nice!

you had me at Orange tape.

[emilio]

good to know they fit, thanks for sharing. i'm always interested in ways to cut engine bay heat, but never really considered fan upgrades.

how's their noise level compared to stock?

- emilio

[Jdsb6s4]

Does anybody know the CFM of the two radiator fans? Or at least some way to figure it out?

I have the front end off to swap out a scurvy helicog accessory belt, and I'm eyeing those two fans thinking maybe I can do better. I was looking at Flex-a-lite's wavy-blade fan and Mishimotos. Ideally I'd simply remove the existing ones (by Nissens?) and swap in the new bad boys, but I guess we'll see about mounting points.

I'm also assuming these are 12-volt fans and don't utilize a transformer to kick it up to 24V. The parts catalogue says these are 400W and 300W fans, which suggests 33 Amps and 25 Amp fans, which strikes me as huge - like maybe I'm looking at it incorrectly. And I don't know how to convert Watts to CFM for fans.

Thoughts and ideas? Thanks guys

Can you post some photos of this?

[Zolli]

Sure, I’ll post some photos. Thanks for the reminder; I forgot all about it. So far the fans have been terrific! My IATs are typically only +10 to +16 *F above ambient, and that’s in the Arizona summer desert, too. Plus they are super quiet. I can easily hear everything else that might go wrong with my car. These things rock!

[Atomic Avant]

Sure, I’ll post some photos. Thanks for the reminder; I forgot all about it. So far the fans have been terrific! My IATs are typically only +10 to +16 *F above ambient, and that’s in the Arizona summer desert, too. Plus they are super quiet. I can easily hear everything else that might go wrong with my car. These things rock!

Thanks for the follow up. I might look into collecting parts for this.

[Zolli]

OK here are some photos for you guys. Thanks to JD for the reminder to follow up.

First, here is a photo of that scurvy helicog belt that started all this. This is the Continental (a brand I DO like) helical-cut ribbed (thus, "cogs") belt that JHM supplies with their automatic tensioner 6-rib kit.

IMG_5649.jpg
Much sadness, and yet...it was still working! I swapped in a Dayco W-rib belt and it has been performing great.

I also discovered what was making the gravel-in-a-rock-tumbler sound I had been hearing from the driver side. Oh, just the bearings for my AC compressor knocked out like a hockey player's grin. Some of you may have seen my other posts about this. I believe what happened is motor oil from a leaking valve cover gasket glued some road grit to the dust shield of the bearing, and the constantly spinning shaft from the engine simply ground away the plastic shield into nothingness.

IMG_7117.jpg

The replacement bearing is 35BX5212-DDST2NB. 35mm interior opening diameter. "BX" I dunno. 52mm outer diameter. 12mm height. "DD" I think means dual...something. Track? "ST" means stainless steel I think. 2NB? I forget. I used to know what the naming code meant. Whatever, that's the one you want. Cost like $30 in 2021.

So to work on repairing this mess and fixing the ubiquitous oil cooler seal leak, I had a reason to swap out the cooling fans behind the radiators. As noted above, I opted for the Flex-waves from Flex-a-Lite, and I'm extremely pleased with them. The difference from the stock Valeos is remarkable. I did some extremely scientific testing to get a determination if there is any significant difference between the Waves and the Valeos. This was like, 2nd-place-winning 4th grade Science Fair stuff. Nearly a Nobel, really.

What I did was this: I hooked up all four fans to a bench-top power supply I have and set it to 12V and 5 Amps (because that's the highest it will go on my equipment). Then I put the fans in a scientific cardboard box, in increasing order of size (so I only had to enlarge the hole for the fans). The box had a cut-out in the back with a scientific credit card flap taped over the hole. As a particular fan blows, the CFM it generates will push the scientific flap open. The greater the scientific flap is pushed back, the more force aka CFM a particular fan can generate. I wanted to see how the Waves stacked up against the Valeos, since we have hardly any information at all about the OE fans. The idea is that the scientific box simulates a uniform non-zero static pressure for each fan.

The smaller of the OE Valeos. BEHOLD, Nips, my friend, the ORANGE TAPE!
IMG_7786.jpg

Respectable performance for an old timer, but we still need to get off its lawn
IMG_7790.jpg

The challenger: Flex-Wave
IMG_7793.jpg

Like whoa, Scoob!
IMG_7794.jpg

Obviously the Flex-Waves crushed the Valeos, but of course the Valeos had some known disadvantages: they were 15 years old, undoubtedly relatively inexpensive for VW / Audi, and they're pretty old tech. Plus, my exceptionally rigorous scientific study mayyyyyy have a few flaws here or there.

Now how to harness these tiny typhoons and set them to work towards my ends. As noted before, yeah... they won't just drop in the openings for the OE fans. So I took the core support off the car and removed the radiators. I had to evacuate the AC refrigerant already to work on the compressor bearing, so that step was already covered. I removed the Valeos and test fit the Felx-Waves and immediately saw that some cutting of the plastic shroud / fan support would be necessary. But it's not egregiously bad; just a little Jigsaw and Dremel work. I made my layout and marked where to cut and where not to cut for mounting points.

IMG_7810.jpg

IMG_7809.jpg

IMG_7807.jpg

IMG_7808.jpg

[Zolli]

This is what it looks like installed in the core support, without the radiators in the way. Minimal trimming.
F8EE5D31-855A-4038-8A7A-99CEF25FC5FC.jpg

These photos show my wire routing on the engine side (I simply spliced into the original wire connectors and covered the solder joint with heat shrink tubing) and the mega-legit shroud I made with aluminum tape to cover all the gaps.

IMG_7860.jpg

IMG_7859.jpg

IMG_7858.jpg

IMG_7857.jpg


The low profile of the fans is sufficient to avoid contacting the engine. I think they are slightly over 3" thick or deep.

plenty of room.jpg

I could drive a cardboard cut-out of a semi truck through there!

The main idea was this: we want the coolant to be 212*F or whatever, right? And we want the oil to be 200*F or whatever, yeah? OK so that stuff has to be hot. But we want the intake air to be at ambient temperature, or close to it (unless we actually chill it). So the problem is heat transfer, in the form of conduction and convection from the engine to the AIT components. I got the phenolic spacers from JHM and did the throttle body coolant bypass, so those help a lot with the conduction. The rest is just hot air not being evacuated and making convection problems. So how about we blast that hot air right out of there with some upgraded fans? That's the concept, anyway.

I have a VFIZ, so I am able to track intake air temperatures while I'm driving around or stopped at a light. The closest to ambient I've had the intake air temperatures is +4*F all day, which is usually in the winter in Arizona. The greatest margin above ambient I've had and recall is +22*F, but that wasn't all day. Usually in the summer it's about +14*F all day, though that still means my IATs are like 120*F, bleh.

Recently I put in an 034 silicone intake hose, so we will see if the smoothness helps eliminate any hot pockets from the OE corrugated hose and helps drop the IATs some more. I'll bet it's marginal, if anything, but it will be interesting to see.

Apologies for image rotation weirdness, where it occurs. AZ's image uploader is pretty advanced for 1998, so I haven't figured out how to easily control the rotation. Just solve it like I do - stand on your or lie down (scientifically, of course) as needed and .

[Atomic Avant]

This is what it looks like installed in the core support, without the radiators in the way. Minimal trimming.
F8EE5D31-855A-4038-8A7A-99CEF25FC5FC.jpg

These photos show my wire routing on the engine side (I simply spliced into the original wire connectors and covered the solder joint with heat shrink tubing) and the mega-legit shroud I made with aluminum tape to cover all the gaps.

IMG_7860.jpg

IMG_7859.jpg

IMG_7858.jpg

IMG_7857.jpg


The low profile of the fans is sufficient to avoid contacting the engine. I think they are slightly over 3" thick or deep.

plenty of room.jpg

I could drive a cardboard cut-out of a semi truck through there!

The main idea was this: we want the coolant to be 212*F or whatever, right? And we want the oil to be 200*F or whatever, yeah? OK so that stuff has to be hot. But we want the intake air to be at ambient temperature, or close to it (unless we actually chill it). So the problem is heat transfer, in the form of conduction and convection from the engine to the AIT components. I got the phenolic spacers from JHM and did the throttle body coolant bypass, so those help a lot with the conduction. The rest is just hot air not being evacuated and making convection problems. So how about we blast that hot air right out of there with some upgraded fans? That's the concept, anyway.

I have a VFIZ, so I am able to track intake air temperatures while I'm driving around or stopped at a light. The closest to ambient I've had the intake air temperatures is +4*F all day, which is usually in the winter in Arizona. The greatest margin above ambient I've had and recall is +22*F, but that wasn't all day. Usually in the summer it's about +14*F all day, though that still means my IATs are like 120*F, bleh.

Recently I put in an 034 silicone intake hose, so we will see if the smoothness helps eliminate any hot pockets from the OE corrugated hose and helps drop the IATs some more. I'll bet it's marginal, if anything, but it will be interesting to see.

Apologies for image rotation weirdness, where it occurs. AZ's image uploader is pretty advanced for 1998, so I haven't figured out how to easily control the rotation. Just solve it like I do - stand on your or lie down (scientifically, of course) as needed and .

Really well done, I like the addition of the metal tape.

I feel like this is something I should have done before I fixed my AC.

Also, that is some mighty fine Orange tape you got there.

[Jdsb6s4]

Thankyou for following up on these photos. And to clarify, did you remove both aux radiators? Also with your wiring it was just a simple cut and reconnect to factory harness?

Too bad you dont have a VFE supercharger on the car to see if the fans still clear with that re routing of the belt.. im not 100% sure if this would work on my application with the charger

[Zolli]

Thankyou for following up on these photos. And to clarify, did you remove both aux radiators? Also with your wiring it was just a simple cut and reconnect to factory harness?

Too bad you dont have a VFE supercharger on the car to see if the fans still clear with that re routing of the belt.. im not 100% sure if this would work on my application with the charger

Currently both of my auxiliary radiators are still installed. The passenger side might get a delete in the near future, but not yet. Wiring was a simple cut and splice, since the fan control is managed by the module before the wire connection to the fans. Only two wires.

And it is DEFINITELY too bad that I don’t have a VF supercharger. Especially after I caught a ride in the supercharged RS4 that the guy who sold me my Q7 owns. Oh man. Tears.

It is the large fan that is closest to anything on the engine. The small fan has the center projection nestled in between the belt routing. They can also be scooted around a little bit within the core support if there’s a tight clearance concern. I don’t recall exactly, but I believe these fans are 3.125” deep from face to that center projection for the axle. The majority of the fan is about 2.75” deep and the motor housing is like 3”.

[Zolli]

It occurred to me that I should clarify that the plane of the greatest extent of the fans (the nubs in the center of the motor housing that contains the fan bearing and axle) is not beyond the plane of the accessory belt and its pulleys. There is at least a 1/4” space there.

I have the 6-rib JHM kit installed, which means that the belt is 3/4” wide rather than the 5/8” 5-rib that’s stock, and I’m guessing that means the 6-rib pulleys are around 1” thick. I don’t know the width of the belt and pulleys for the VFE supercharger kit, but most likely it’s not greater than a 3/4” belt width. Hopefully that helps provide a little clarification.

[Jdsb6s4]

and Keith I just want to add that im sorry that we didnt make the move to scottsdale! We were so close to making the move there but things ended up working out to our favor. We did just visit this last July which was suppose to be our house shopping trip... It was hitting a good 115 degrees that week, I fully understand you fan upgrades. I would been struggling to drive the avant around without A/C but the engine would manage fine with the WMI setup:). Thanks for sharing your fan mod!

[Zolli]

No apologies necessary! This is a great spot to live, especially if you have somewhere else you can be June - September. But there's a lot of great places to live in this country. If you find yourself in my neck of the sun's surface again, hit me up - I'll buy you a drink / burger / milkshake.

I've been eyeballing WMI thanks to these temps. I'll get some tips from you when I pull the trigger.

[WileyBrill]

zolli, from what I've observed, you are truely an HVAC/Engine Coolant "Whisperer" (as a compliment)
Would you please - go to "A/C intermitent" and see if you answers for my posted questions, therein - when you have time.

Thank you.

[Zolli]

While I've been fooling around with my suspension and power steering refresh, I tried installing an air dam on the passenger side between the auxiliary radiator and the stock airbox.

I have a cold air intake waiting to get installed, but I've often heard that the waste heat from the passenger side aux rad effectively negates the cold air intake attempts to snort "cold" (let's be honest - it's ambient air) air and could actually make it worse as it gets the hot air coming from the back of the aux rad.

While I had the suspension components out, it gave me an opportunity to have a look at what's happening in that area of the engine bay. It appears that the fender liner causes a diverting effect that routes the hot air coming from the aux rad up to the airbox. Well obviously that's a bad idea. I am betting that if I can re-route that hot air, I can keep the aux rad in place and hopefully manage those intake air temps a bit more and maybe a CAI will work as intended.

Here's an image of the concept I'm trying out:
21936931.jpg
The yellow is the airbox, the green is the aux rad, and the blue is the air dam. The red arrow is that hotttt Arizona desert air.

Heat soak I'm attempting to deal with by utilizing reflective foil and insulation combined with Typhoon-class fans (Vasili, one ping only, please). But hot air, while moving, I can hopefully divert away from the air box.

First thing I did was remove the SAI pump. I already have it tuned out (Jackal), so it's just dead weight and in the way, tucked right behind the aux rad. Side note: I didn't want to figure out how to remove the SAI tube and put in the JHM block-off plates, so I left the metal tube in place and just fabricated a little plug for it with a short length of hose and a cap. I'll let you know if I get any codes or shart out a plug from the exhaust.

Next I cut out an air dam from some DEI Form-A-Barrier and squeezed it in there. I made a test piece out of cardboard to figure out where to make the openings for the coolant lines, refrigerant lines, and wire harnesses going through that area. I still have it if anyone wants a copy for a template.

Looking down at it, before I put aluminum tape on it to seal it up:
IMG_1473.jpg

IMG_1474.jpg

Looking up from underneath and behind the aux rad:
IMG_1477.jpg

The air dam blocks off the space between the top of the aux rad and the bottom of the airbox. It also wraps down the side a bit, but not 100% (I may do that if needed). I still needed to provide access to those 10mm nuts that hold the bumper on. Mashing it in there is a little fussy, but it fits nicely.

Last, I cut out a section of the fender liner to provide and outlet for the hot air from the aux rad. This will allow the hot air to exit the engine bay and not blow up to the airbox anymore. I got some perforated metal I had and riveted it to the liner. It's on pretty firmly. It oughta work.

Here's the fender liner opening from the interior, looking toward the back of the car:
IMG_1475.jpg

The car isn't off the jackstands yet, so I'll report in with whatever IAT results I get reported from my VFIZ.

[Atomic Avant]

While I've been fooling around with my suspension and power steering refresh, I tried installing an air dam on the passenger side between the auxiliary radiator and the stock airbox.

I have a cold air intake waiting to get installed, but I've often heard that the waste heat from the passenger side aux rad effectively negates the cold air intake attempts to snort "cold" (let's be honest - it's ambient air) air and could actually make it worse as it gets the hot air coming from the back of the aux rad.

While I had the suspension components out, it gave me an opportunity to have a look at what's happening in that area of the engine bay. It appears that the fender liner causes a diverting effect that routes the hot air coming from the aux rad up to the airbox. Well obviously that's a bad idea. I am betting that if I can re-route that hot air, I can keep the aux rad in place and hopefully manage those intake air temps a bit more and maybe a CAI will work as intended.

Here's an image of the concept I'm trying out:
21936931.jpg
The yellow is the airbox, the green is the aux rad, and the blue is the air dam. The red arrow is that hotttt Arizona desert air.

Heat soak I'm attempting to deal with by utilizing reflective foil and insulation combined with Typhoon-class fans (Vasili, one ping only, please). But hot air, while moving, I can hopefully divert away from the air box.

First thing I did was remove the SAI pump. I already have it tuned out (Jackal), so it's just dead weight and in the way, tucked right behind the aux rad. Side note: I didn't want to figure out how to remove the SAI tube and put in the JHM block-off plates, so I left the metal tube in place and just fabricated a little plug for it with a short length of hose and a cap. I'll let you know if I get any codes or shart out a plug from the exhaust.

Next I cut out an air dam from some DEI Form-A-Barrier and squeezed it in there. I made a test piece out of cardboard to figure out where to make the openings for the coolant lines, refrigerant lines, and wire harnesses going through that area. I still have it if anyone wants a copy for a template.

Looking down at it, before I put aluminum tape on it to seal it up:
IMG_1473.jpg

IMG_1474.jpg

Looking up from underneath and behind the aux rad:
IMG_1477.jpg

The air dam blocks off the space between the top of the aux rad and the bottom of the airbox. It also wraps down the side a bit, but not 100% (I may do that if needed). I still needed to provide access to those 10mm nuts that hold the bumper on. Mashing it in there is a little fussy, but it fits nicely.

Last, I cut out a section of the fender liner to provide and outlet for the hot air from the aux rad. This will allow the hot air to exit the engine bay and not blow up to the airbox anymore. I got some perforated metal I had and riveted it to the liner. It's on pretty firmly. It oughta work.

Here's the fender liner opening from the interior, looking toward the back of the car:
IMG_1475.jpg

The car isn't off the jackstands yet, so I'll report in with whatever IAT results I get reported from my VFIZ.

looks good!

have you considered removing the Aux rad?

[Zolli]

I have considered it, but that’s Plan L. I’m currently on Plan E. So I’m not there yet.

You see, I bought a house on the surface of the sun (Phoenix, Arizona), so I’d like to preserve as much heat exchange as I can. And I don’t have the budget for meth injection yet.

Thus the experiments! (Mad scientist cackle)

[Zolli]

Some updates with a little data logging from my VFIZ.

The trouble is heatsoak. I have it managed well enough that only very long stoplights trigger an increase in intake air temps. The typical driving intake air temperature is +12*F above ambient. Even after heat soaking the engine bay for two hours, I can get it back to the +12*F margin after a few minutes of driving (lots of stop lights would probably increase that time). The AC on increases the margin a little bit to +16-ish.

Initial start, engine cold to warm:
71 ambient temp
82 Intake Air Temp (+11)
68 to 203 Oil Temp
72 to 194 Coolant Temp
Fan at 42%

Stoplights, about 15 of them
72 AmbT
93 IAT
198 OilT
201 CLT
Fan 54%

Two hour heat soak
72 AmbT
124 IAT (+52)
147 OilT
168 CLT
Fan 0%

After heatsoak highway driving mayyybe a few mph over the speed limit
67 AmbT
79 IAT (+12)
203 OilT
195 CLT
Fan 52%

So far, I’d say it’s not clear that the air dam and fender liner vent is providing any benefit. That might be more useful in the summertime.

An interesting thing I noticed the first time I took it for a spin after completing the hot air dam and the suspension upgrades: the car seemed to be struggling to lower IAT after heatsoak.

I think it’s because I also finally corrected my bumper position to get rid of the egregious gap between it and the hood when I was wrapping up the other projects. I was able to shrink the gap down so well that it looks awesome, like to 5mm, but it might have been choking off the main snorkel’s access to fresh air, which is supposed to come in through that gap. I don’t know if that’s true and correct, though. I’m guessing that the smaller gap meant it had to get air from closer to the radiator, so the initial air temp would be warmer. Just speculation.

I went ahead and fabricated a quick little ram air scoop like ECS’s Luft Technik one. I used a plastic container lid, a sheet metal paint sample, and some rivets to make a deflector scoop that captures about six of the grille grid openings. Kind of a test piece, but I painted it black so it’s a little less embarrassing. Anyway, it seems to help, in that it appears to enable the car to get back to the typical +12*F IAT margin.

Well, the saga will continue.... I recently received my ported throttle body and intake (woohoo, thanks to Full Send Motorsports). I’ll install that late December and then add the cold air intake at that time. Noting the heat soak issue, I will probably figure out some insulation strategies.