1973 Rebuild

[Matthew Abate]

Okay, I know versions of this question have been danced around for a while but I’m having a hard time finding real information on it so I’ll risk the ire and ask it anyway:

Has anyone compared the cross-flow radiators (Koyorad or MSA) to the 3-row radiators at Z Car Depot and MSA with a shroud?

I’ve been going back and forth on this for a while and have seen speculation but I don’t think anyone has gone directly from one to the other and captured the results. Most of what I’ve found on this site and Hybridz is discussing going to one of those options from the factory radiator.

Right now I can get a Koyorad cross flow with the correct cap for $427.74 (plus tax and shipping).

I can get the 3-row from MSA $362.67 (plus tax and shipping). I think Champion makes these.

They also have the 2-row high flow, but I’ve never seen anyone talk about those. That would cost $352.57 (plus tax and shipping). I think this is also from Champion.

The Koyorad is cool and I’ve seen a ton of anecdotes about it cooking really well. Everyone who posts about theirs seems to love them.

I’ve seen a ton of horror stories about the Champions leaking after a year or two. Based on that I was about to pull the trigger on the Koyo, but I really don’t like that it can’t take a shroud. I also don’t love how far down the bottom of the radiator comes and that they don’t have a drain plug.

I won’t complicate things by mixing the options at Z Car Depot into this, because I think those are mostly the same as the ones at MSA (except maybe the “Ultimate” one, but I’m not spending $669 on this).

If anyone has done actual comparisons between these, either by swapping from one to the other, by installing them on multiple cars, or through some other means of getting info about their performances, please chime in.

Oh, and then there’s always the CSF brass/copper option… 🤪

Edited August 19, 2023 by Matthew Abate

[dutchzcarguy]

6 hours ago, Matthew Abate said:

and then there’s always the CSF copper option… 🤪

I don't have any experience with Aluminium or aluminum radiators.. i only know that i will ALWAYS go for copper!  Aluminum cracks much easier and copper cools way better than aluminium will EVER do! (It's a natural fact!)

I don't care what people say about alu coolers.. they just don't belong in a Datsun.. period. 😮

Another option would be a firm that makes/repairs old radiators with a new core. I would look for a firm that does that, i would pay a lot more for that kind of quality!

(We have one in the Netherlands, the specialism went from dad on son.. Don't know theire name but it's somewhere on youtube..)

[dutchzcarguy]

The Brassworks; handcrafted radiators made in the USA

[Matthew Abate]

1 hour ago, dutchzcarguy said:

I don't have any experience with Aluminium or aluminum radiators.. i only know that i will ALWAYS go for copper!

https://www.hotrodhotline.com/md/html/aluminum_vs_copper.php

[dutchzcarguy]

The problem with aluminum, it brakes down.. the radiator in my 240z is at least 30 years old and it would not surprise me if it's his first rad. (so 52 years old.)

from hotrodhotline:

At this point the move to aluminum construction was purely financial in that raw materials are purchased “by the pound” and a finished aluminum radiator weighs about 25% of a copper/brass unit (dollars per pound being almost equal at that time) and resulted in huge savings to the O.E.’s .  This is why we’ve seen most copper/brass manufacturers either switch to aluminum or fold up their tents permanently.  It is important to note that this decision was based solely on financial savings and should not be confused with more efficient.

Still the old is more efficient and alu is for cheapskates! 🙊😂

[Matthew Abate]

It’s far more complicated than “copper is better than aluminum.”

Yes, a chunk of copper transfers heat better than a chunk of aluminum. However, if you look at computer heat sync design, you’ll see that they frequently use a copper base to pull heat out of the devices, but then have aluminum vanes to radiate the heat because of aluminum’s ability to transfer heat to the air. I don’t know the science in this, but I have read in a handful of places that copper is better at absorbing heat and aluminum is better at expelling heat. That might be suspect, but it might be true.

Also, copper radiators are tin soldered and aluminum radiators are brazed/welded with aluminum. Tin soldering inhibits the heat transfer between the copper pieces, reducing the overall efficiency of the radiator as a whole. Welding doesn’t introduce this problem, so that brings the net effect closer together.

Additionally, aluminum is stronger, which allows manufacturers to use different designs and to have denser tubing throughout the core, not to mention parallel flow vs serpentine, etc. A copper radiator made the same way would weigh 100 pounds.

Add into that the quality of the manufacturing and you are 100% precluded from saying a copper/brass radiator is always better than an aluminum one. I already know that (on a test bench) a Koyo cross flow is more efficient than a copper 3-row, and that is because of the design.

But that doesn’t mean the Koyo is the better option. The fact that it can’t take a shroud negates some of that better design and manufacturing. But people still rave over their Koyos, which is why I am looking for real world experience with Champion vs Koyo.

So if we could get back on topic and look at the performance of specific radiator models against each other I would appreciate it.

Edited August 20, 2023 by Matthew Abate

[Zed Head]

Maybe this guy will run a comparison.  He does some pretty neat stuff.

https://www.youtube.com/@ProjectFarm

[Matthew Abate]

One of the many, many things the painter screwed up on my car was not painting the back of the air dam black like I asked him to. Not the most egregious screwup by far, but still annoying when compounded with everything else.

I hit this with gloss black and it helps. Doesn’t fix the spots where the primer is showing through the orange but it’s better.

[Matthew Abate]

I blacked out the radiator bulkhead and grill tabs (thanks @Patcon for the thread showing how that’s done). Now I just need a 280z harness boot and I can put the engine harness in.

[Patcon]

What do you need?

[Matthew Abate]

I’m good. I had ordered a harness boot from zcardepot that was labeled 1970-73, but I should have meassured the hole first. JDM Car Parts and MSA have the 280 boot, so I have one in the mail. Once I get that I can put this thing in, then on to fitting the body harness.

[Matthew Abate]

More progress…

I fabbed up a bracket for my Sanden compressor because modifying the ZX bracket was turning out to be just too much. I used the Vintage Air universal bracket parts ($50 @ Summit) and a sheet of 1/4” steel from the hardware store, which I cut, drilled, and welded to the brackets.

It came out okay.

If I were going to do it over again (which I’m not) I would angle the bracket up more to 1. make more clearance for the compressor to slide in under the bracket, 2. move the compressor away from the frame when at the furthest point of adjustment, and 3. change the adjustment angle to be more perpendicular to the block, making the adjustment span more pronounce/longer.

Otherwise I’m happy with it.

Edited October 2, 2023 by Matthew Abate