watercooling rads a couple decades behind?

Skip to the bottom to see the TLDR and afterthought first so you know if you want to read it (sorry for the length)

This is kind of ironic since I'm saying they're behind by longer than they've existed... but let me explain.

I pulled a heater core from my 1999 isuzu npr-hd (one of those old flat-fronted box trucks). It was leaking after nearly 300,000 miles.

In the FSM it states the heater core dissipates 4.5 Kw of heat. Yes, 4,500 WATTS of heat. Don't forget that's out of a 45mm thick, 170 mm wide, and 220mm tall package.

Of course, that's at an operating temperature of 100*C (75*C delta from ambient which is stated as 25*C), far hotter than what we want to run our CPUs at.
But even so, lets say we wanted 60 C, (35*C delta) that's still just over half the heat dissipation or 2,400 watts.

Then we have to consider that it's an automotive blower pushing air through this thing (although admittedly the blower, even when new, wasn't all that strong), not a computer fan, so maybe our 2x 160 mm SP fans can only push a third of the airflow, that's still 800 watts of heat dissipation, and out of such a small package compared to a 60 mm thick 360mm radiator for watercooling.

How? turbulence. basically the same reasoning why they use dotted CPU waterblocks now instead of fins.
by having interruptions in the surface of the air fins (literally just tiny slits about 3x the distance between the fins), it creates turbulence which causes fresh cold air from the center of the stream to replace the hot air right next to the fin.

It's also benefited by having 23 FPI, but with a super thin metal (just zig zagged to maintain its structure/resistance to bending) while providing less resistance to airflow.

this heater core uses a 3x12 grid of 4.5 mm round tubes rather than the wide flat channels used in normal heater cores, radiators, and PC watercoolers. I presume this is to make it easier to manufacture due to the design, and to hold pressure better/with less movement (expansion/contraction of the normal flat tubes)

To get better heat dissipation they put plastic zigzags in them
This forces the water to swirl around it, again creating turbulence to make sure all the water reaches the surface and release as much heat as possible. (plastic cause it's cheaper and wont abrade the inside of the tube when they move around)

Also, the 3x12 grid forces the air to swirl around the "posts" in the fins, creating horizontal turbulence in that way (not much of a benefit compared to the slits).

As I see it, air cooler manufactures, with their heatpipes and stacked aluminum fin manufacturing techniques would definitely be best suited to making these in a more standard size for PC watercooling use. additions to their current tech would basically just be pressing on end plates and then tanks to the end of those.

automotive heater cores from the as far back as the 90s have numerous technologies to aid turbulence and vastly increase heat dissipation compared to PC watercooling radiators, serve for much longer periods in much harsher conditions, and generally for a much lower price for the performance.

Here's a pic of a similar one which shows the construction style


AFERTHOUGHT: after typing all this, I just realized this- it's basically a 23 FPI heatpipe aircooler but with 36 pipes and coolant running through them instead of refrigerants, and a lot of turbulence generators to ensure the absolute maximum heat transfer.

Also, I fixed the leak with some jb-weld, pressure tested it overnight at 20 PSI (1.4 bar) and it didn't leak, so I'll be using it in my <$50 junkyard overclocker PC. It fits ever so snugly (aka barely squeezed it on) between the sidepanel and the other side of the case of my generic 90s whitebox.

EDIT: I'll clip off a bit of fin and measure the thickness later and compare it to a Radeon HD 4870 Dark Knight's fins (another dumpster dive find).
Reply to Woofythewolf
4 answers Last reply
More about watercooling rads couple decades
  1. Motorcycle radiators can also make awesome CPU coolers. Most of them come with threaded fittings for easier (and safer) mounting. They are also more efficient because they need to be compact and are also ore robust because of environment they have to run in.
    Reply to CountMike
  2. condensation would be why I'd imagine PC water cooler rads aren't like Car rads.
    Reply to James Mason
  3. CountMike that's a good point. Although I'd imagine they'd be a lot more expensive (maybe not though).
    EDIT: not too expensive on amazon, and they come in some interesting shapes (curved, angled in the middle, etc.). However I can't find any that use the fins-on-tubes arrangement.

    James what do you mean by condensation? if everything is above ambient temp then it shouldn't be an issue?

    I'm kind of worried about cooking my GPU with this though. (aircooled GTX 460 SE is going right by the output of this, and it hits 75 C with plenty of fresh cool air, So it may overheat when it's recieving 40-50 C air)
    I may print some ducting to route air from this to the back of the case instead of emptying into the case.

    For anyone saying it's weak, well I got it free and it overclocked from 648 to 925 MHz on stock cooling. :D plays CSGO on med/high settings 60 fps.
    Reply to Woofythewolf
  4. I've used heater cores before for watercooling and they work well, so this is really more of just an issue of 'being behind'...its about marketability. The average newcomer to watercooling is already inundated by massive options for pumps, rads, fittings, blocks, tubing sizes, etc than to think about 'what else could I use'?

    The PC watercooling radiator design is such that it is user friendly and meets the mounting options that are common in most PC cases, eg: what size fans are commonly used and follow that. Automotive or cycle coolers adhere to the specs needed for their use. Also, for cars and bikes, the water pumps are usually more robust and some of these cores or radiators are designed for that type of flow whereas PC watercooling pumps don't necessarily meet the specs designed to move coolant through these and PC radiators are. This still doesn't mean they don't work fine in most scenarios, because they often do.
    Reply to rubix_1011
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