Mount radiator to your drill press and use an annular cutter around the mouth of the inlet & outlet to cut them down.

 

Mostly because I think I'm going to try using a Mk1 (First generation 84-89) MR2 AW11 Radiator



It meets with the vast majority of my requirements. Its a crossflow, it has the hose nipples on the correct sides and at the correct heights, its all aluminum so if I need something welded to it there won't be toxic cat pee vapors.

According to the listing for this MR2 AW11 radiator...
Core Size: 22.5" x 12.5" x 1.25"
Overall Size: 26.5" x 14.5" x 1.25"

I pulled a set of dimensions from a random eBay listing for an all aluminum NA Miata radiator...
Core Size: 25.5" x 12.5" x 1.57"
Overall Size: 25.6" x 17.5" x 4.3"

Who knows if any of these measurements are accurate, but as far as the exterior dimensions the MR2 unit is about 1" wider in total, and about 3" shorter in height. It makes sense that the core would be narrower because its got end tanks on the ends, and the shorter height helps me with my ground clearance concerns. It also uses bog standard 1.25" ID hoses so I won't have to adapt anything. According to my "tape measure in the dark" there is about 28" between the frame rails on the NA so... I think this'll fit! Like the VW radiators it requires the use of a remote filler, but I seem to remember inline fillers with caps are under ~$20 from the usual scumbags, and I'll be able to continue to use the stock NA coolant reservoir. Another option would be to just weld a filler neck and cap assembly on the top of the cold tank, I'll definitely have the room to do it with the overall shorter radiator. In fact, that might be the best idea as it doesn't add points of failure. Unfortunately, Rockauto doesn't list a radiator at all for the first generation MR2 so I'm stuck with ~$100 ebay options. Which isn't necessarily a bad thing, I was just hoping there would be a $45-$75 OE style Denso option. I don't like committing to something with limited availability outside of eBay.

I'll probably have to remove the NA radiator mounts from the frame rails and jig up my own mounting system, but I can hand wave that away pretty easily. One thing that is kind of a bummer is that I won't be able to use the MR2 fan assembly. The fans are SUPER ridiculous deep, check it out:



I like repurposing OE stuff but there is just no way that is going to fit between the radiator and the accessory drive on the front of the BP05.

I'm sure I can fit at least one stock Miata fan on the back of that thing (maybe rotate it 90°) and if it turns out I need a second fan, I can always bias the stock Miata fan to one side and put a pusher in front of the radiator biased in the other. I've still got the wiring in place to take advantage of the stock AC fan relay which makes for a perfect place to hook in any generic aftermarket fan, provided its not a billion amps. If I even need a second fan.

I'm pretty excited to have found this. I'll spend a bit more time down the rabbit hole to make sure I haven't missed anything, but this might be where I go next. Mucking with the Miata coolant system is always dangerous, but with the reroute I'm fairly confident this'll work.

@Joe Perez , its shocking how much our Youtube watching habits overlap

 

Looks like a good match, would prefer something thicker but guess it will work.

+1 on YT habits.

 

That looks like it'll do.



Is it?

I forgot the last step: Tony realizes, once the assembly is finished, that he mis-calculated the bend radius of something or other right at the very beginning, and so out comes the angle grinder.

 

Yarp. I was kinda hoping there would be some ~$100 "race" version of that radiator on eBay that was significantly thicker/overbuilt, but I suspect there may be some space constraints in the OE packaging that prevent it. This very well may not be "enough" radiator for what I'm trying to do, but that's fine. I like tinkering.

I'll probably start by setting this up with the stock ducting and them block off the air gaps just to see if its feasible, then go from there. I don't want to start building other things around this form factor before I know for sure that it'll work.
This is not a track car and it's not highly stressed, so I think I'll be OK, but one step at a time.
Wait... this isn't how all projects are supposed to work?! 🤯

 

lolololololol... You say that now! Just wait until you're in the middle of nowhere Oregon and some drunkard in a real **** box has beaten your time trial time by 2 seconds.

Always overbuild!

 

Any chance that you can accommodate the extra wideness of a 2nd gen MR2 radiator? Mishimoto makes a 3-row version of that one.

 

Sorry I missed this previously...
It seems to be fine? When I first got everything installed but before it was aligned, I took it over to the local dead mall and YOLO'd it the **** over some speedbumps at felonious speeds (for a parking lot) and at odd approach angles and it didn't seem to get too upset. After the alignment I drove it through the above construction site to see if I could find some gnarly bumps or pipe trenches to fall into, but beyond that I haven't done much driving at all. We're getting between 0.25" and 1.25" of rain per day up here right now so I'm trying not to drive the car in deference to the welding that @gesso has kindly agreed to do for me on the wheel well seams. I don't want to make his work harder by getting a bunch of garbage in the wells and seams. I also have no goddamn clue what the AFRs look like on this thing as I'm still waiting for a test pipe with the o2 bung. I don't want to burn it upquite yet

Although I will admit I did do a rather aggressive redline blast down the highway to see if the JRSC would throw the belt or if the engine would explode first. Thankfully neither happened, but I'm trying not to push my luck at the moment.

That assumes I'll lift? haha! Lets be honest, if you bring the truck and this thing explodes, you'll most likely be dragging me home

Also, everyone always beats me by 2 seconds! I'm slow as frig, its a universal constant. @Scaxx will have me by a mile
I'm trying!
I looked at the Gen2 (89-99) MR2 listings and the generic dimensions show 29.75" for width, and my "tape measure in the dark" was 28-and-a-bit. I don't think it'll fit but its something to take into consideration.

If its not raining buckets this weekend, the local Cars & Coffee is on Saturday. I think it would be highly entertaining to participate with this car Its either that or I pull the front end apart again and take real radiator space measurements. I could go either way, really.

 

Quote:

Originally Posted by EO2K

If its not raining buckets this weekend, the local Cars & Coffee is on Saturday. I think it would be highly entertaining to participate with this car Its either that or I pull the front end apart again and take real radiator space measurements. I could go either way, really.

Revising my bullshit, C&C is next weekend on the 6th. Looks like I'll be pulling the radiator out and taking for-real measurements this weekend.

New data: Volkswagen Mk3 radiator may be a contender:

1994-1999 in North America. The above radiator is $82 on ebay right now. For those not living in the glorious metric future, that's 27.4" W x 14.6" H and 1.25" standard hose barbs. The description doesn't state the number of "rows" but the core thickness is listed at 1.56" so I'm assuming its single row. There may be dual row units with thicker cores in the same form factor, I'll do some more reading tonight. It's also set up for a remote fill, but again, that's not an insurmountable challenge. That saves me a solid 2-3" on height compared to stock Miata, which is exactly what I'm looking for. Nice.

As another data point, I've been somewhat reliably informed by someone who tried to put a KoyoRacing KH082661 (from a 9th gen Civic Si) into an NA that it didn't fit for width. According to Koyo that radiator is 27.5" wide, but I'm unsure if they removed the NA mount tabs or not. I've also been somewhat reliably informed by another person that the "frame rails" widen out past the core support so there might be some additional room if the radiator is moved forward? I'm not afraid of cutting out the crossbar behind the bumper on this car so that may come in to play as well. I think the tape measure will tell the whole story here.

Apologies for the stream of thought radiator nonsense, I'm sure this isn't the retardation you came here to see.

 

image shows rad upside-down....

anyway, thats a good price to play with, not a killer if it's not getting used

Rich.

 

That had occurred to me. Upside down probably still cools just fine, though I'd have to put an air bleed on the top tank and pay attention to keeping it properly bled. Or move the inlet nipple hose barb thinger to the top.

A stock replacement one for a MK3 VW can be had on Rockauto for $32 https://www.rockauto.com/en/catalog/...,radiator,2172

But not in California, apparently.


The state has to make sure its saving me from the cheap radiator cancer

 

No no no... It is known to California that cheap radiators cause birth defects and reproductive harm, not cancer. That is some of the other products.

 

Big oof.

 

Holy ****.

Dude.

Twenty seven AND A HALF?

Mind = Bl0wn.

 

Told you. Miatas don't have those birthing hips.

 

 

^^ This is true.

I wonder if anyone I know owns an Enerpac...

 

won't need one, scisor-jack & a block of wood should do it

Rich.

 

Working on this car is entertaining, I never quite know what I'm going to find.


F O R B I D D E N O R A N G E J O O S E

I haven't actually ever taken the radiator out of this car so this was enlightening as to why I couldn't get the lower radiator hose to seal. Its amazing what you don't notice while lying on your back and wrenching in the dark.




I suspect this is more fuckery imparted by the shop that the PO paid to replace the coolant hoses. I can probably swage that back to round with a couple sockets, or I can make a basic mandrel on the lathe and pop it back out. No matter, I'm not planning on using this radiator in the long term anyway.

I also discovered that the power steering fluid level is self regulating



So that's highly convenient

I removed the stock radiator side mounts and got some real dimensions.



Lots of room for activities in here with no sway bar. I'd have removed those mounts too but Mazda decided that the 4 bolts weren't enough and added some spot welds. Argh.

And with that, I think I'm finally ready to order a radiator! Much excite!

 

I also found this on Craigslist, and I'm fairly excited about it.



Its 3/8" thick and about 41.5" wide. Depth is about 12" and the front lip is bent up at almost a 45° angle, and the front corners are nicely rounded. This was being sold as a "skid plate for a 4x4 front axle" and cost me $20



Stuffed up under the nose, its a remarkably good fit.



It extends back into the front of the front wheel wells, but doesn't get anywhere near the tires. Please ignore all the **** piled in my garage, I have a hoarding problem I'm trying to sort out.



Blue line on the undertray represents the approximate "centerline" of the factory style radiator. This almost makes it far enough back to cover it.



If I could get this back another couple inches it would cover the bottom of the radiator.



If I cut the bottom lip out, I think it can happen. I'm going to need to do some thinking.

While under the car this weekend I noticed another item that needs to be addressed: fuel and brake lines



As you can see the car has a set of FM Stainless rails on it, which are very nice rails, but the "solution" they came up with for mounting the lines is fairly bad with regards to ground clearance. There are a pair of tiny studs sticking vertically out of the bottom of the rail, therefore making the stud that retains the OE hangars the absolute lowest spot on the bottom of the car. As you can see, its actively pulling the lines DOWN and making them more vulnerable. Here's a snip I grabbed off FM's website to make it more obvious:



You can see one of the little studs on the right side of this image (rail is upside-down as pictured)

Based on the condition of the little studs they are more than familiar with speed bumps. That... is not a solution. When I put the FM rails on my NB I drilled and tapped through the side of the rail for little Mazda M6 bolts I have left over from somewhere and tucked the lines up against the bottom of the chassis. I took great care to cut the big honking rail hardware down so that it wouldn't punch through the lines in the event of contact. My needs on the NA are a little bit more extreme, so I'm going to have to get a little more creative to protect the lines this time around.