What are the considerations for fitting a radiator from a completely different platform? I can pick up an unused Summit Racing #380473 all-aluminum, 2-row radiator for $200 locally. At $100 off, it's not such a screaming deal that I'll kick myself for passing it up, but I'm intrigued whether I can make it work. It's designed for Chevy S10 V8 retrofits and has a built-in tranny cooler, just like our stock unit, although confirming hose sizes is difficult. (I'm also told that a C4 Corvette radiator is half the weight, $100-150 new, and a very similar fit, although the measurements I found indicate it's quite a bit smaller and has odd inlet/outlet tube measurements.)

Listed measurements for the Summit unit are 30.75" W x 15.875" H x 3.125" D, although the depth is actually just a hair under 3" according to the seller. Inlet and outlet tubes are both 1.5".

Rough measurements on my '94 SC400's radiator are 29.75" W x 1.5" D. I couldn't get much of a height measurement due to all the stuff in the way, but it seemed like 20" top to bottom. Other stuff I've seen suggests closer to 16". The upper tube looks to be 1.5" and the lower tube is either the same or ever so slightly smaller.

It looks like I have 1/2" of space to either side, so if the 30.75" of the Summit unit is accurate, it would be a very tight squeeze but just barely doable. There's almost exactly 3" of clearance to the battery tray, making the depth pretty much perfect. One area that could be an issue is the upper tube hitting the corner of the battery, being way over toward the driver's side of the radiator. However, a battery relocation to the trunk is one of my hopeful mods.

My reasons for considering doing this include: 1) reduce front-end weight, 2) free up space (width) between the coolant reservoir and upper tube for my hood vent project, 3) eliminate the awful coolant reservoir setup, and 4) get rid of my slight hydro reservoir leak. I'm not 100% sold on the Summit radiator being my best bet, but radiator/fan simplification is something I've had on my to-do list for a couple months and this one got me 'a thinking. Having the upper hose as far from center as possible, and not being tied to the silly big and fragile coolant reservoir on the other side, would help a bundle with the hood vent.

Reasons for not doing it include having a fairly new radiator in place already, a brand new coolant level sensor, a coolant reservoir that doesn't yet leak, and a hydraulic fan that functions properly despite seeping a bit below the reservoir.

Now, I know the drawbacks -- expense, time and effort, inferior cooling with electric fans, having to run a separate tranny cooler -- but I think most of that is addressed by a radiator with a built-in tranny cooler and the added cooling of the hood vent. A small e-fan to move air while idling ought to be sufficient, I would think. I imagine I would have to extend (or fully replace) the tranny oil lines to be up on the side of the radiator instead of down along the bottom, and the radiator hoses would have to be replaced by non-formed ones to reach their new location. Neither seems like a deal killer. The LS400 idler pulley to replace the hydro pump is the main thing I would need to source. Time/effort isn't really a factor, since I wouldn't be tackling it if I didn't want to do it.

Fitment aside, it seems like the big uncertainty would be mounting. People put the thicker Koyo Supra radiators in and make it work by putting some padding below so the top mount is snug. Other than the shape of the radiator differing up top from stock and maybe requiring the top mounts be trimmed or replaced with something of a different shape, is that all there is to it? I don't see any other mounting points in the various pictures.

 

It can be done lots of people do it but usually on hot rods or ones where a more direct fit isn't available.
fitting it in takes custom brackets but you do want the water necks in the right place or you will need custom radiator hoses.
I have seen tons of smaller aftermarket multiple row radiators used on 1jz/2jz truck swaps where the regular supra/SC ones won't fit.
a good set of E-fans will get the job done but consider doing an alternator upgrade for some more amps at idle cause the fans will add a good amount of load at idle. not a must do if you don't have alot of extra electronics but if you have a sound system etc... etc.. it might be a good idea with the added e-fans.
I know the 2uz tundra 150amp version can be fitted to a 2jz with shaving one mounting tab a little, I imagine it would fit on the 1uz easier but haven't read about anyone trying so I don't really know for certain.

 

anyone fit an MR2 Turbo Radiator?

 

Custom brackets being the upper and lower supports/clamps, right? Lining up the inlet/outlet with anything but a OEM replacement radiator seems like a pipe dream... Is going away from stock radiator hoses really that big of a deal? Having them pre-shaped obviously helps clear drive belts and what not, and any tubing of that diameter is going to be tougher to bend to fit a space. I suppose I should start by searching for other OEM hoses of the proper diameter that would reach the new locations. Can anyone confirm the SC's inlet and outlet as both being 1.5"? I'd hate to find out that my estimate was off by 1/16", and I've yet to find specs posted.

That's why the local guy is selling the S10 radiator. After test fitting it with the V8 swap, he realized there wasn't enough room for the fan, so he went with the shallower Corvette one.

My hope, if I go ahead with this, is to start simple and see what temps look like with the hood vent and no fan. Even at idle, allowing the heat to rise up and out of the hood directly behind the radiator ought to do somewhat the same thing as pushing it into a hot engine bay with a fan. If temps stay in check at idle, they should be good to go when at speed. If not, then I figure out how much fan is needed to boost the air flow. Thanks for the suggestion on alternator upgrades. I hadn't considered that as a related element. I was mostly thinking along the lines of keeping the fan(s) as small as possible to avoid that extra load.

I read some Supra stuff suggesting braided lines for additional tranny coolers, insulated from the hot turbo downpipe if applicable. I imagine I could go that route for extending the current lines to the new location up higher, and not have to run all new lines.

 

Its not a big deal changing the hoses no, I mean it just has to be physically possible to route them. like on a gte you wouldn't want the waterneck all the way on the passenger side cause the coolant pipe points towards the drivers side so you would have some pretty funny looking piping.
I took a look at that radiator and the pipes seem on the right sides generally, about the size I dunno haven't even mearures the SC one.

Your car will overheat without a fan unless you are driving fast enough to push air through there, there is no doubt about it. it would do it with your current radiator also. you will need some kind of fan. I would think a supra aluminum radiator would be much simpler and you can even use maybe the ls400 clutch fan setup and your stock fan shroud.
I always prefer a good ol clutch fan there is no eletricity draw to worry about or wiring etc... and you need the ls400 clutch fan base anyways to hydro delete.
I think I have an extra sc300 clutch fan in my garage but not sure if it will bolt the the ls400 base, I would try and get one with the ls400 as a whole unit.

 

Aren't there some sports cars that use fan-less radiators, made possible by big hood vents that allow the heat to escape? Do they have some other trick up their sleeve for dealing with no wind-assisted air flow?

Are their any Supra A/T radiators with the built-in tranny cooler? That's the main appeal of this Summit unit, being able to directly replace the stock SC400 one's functionality. I mostly just need to confirm hose sizes. Has anyone seen a spec sheet for the SC's radiator?

I'll have to look into the LS clutch fan setup...

Most of all, the reason I want to do this is to get rid of that godawful coolant reservoir that all us 1st Gen SC4 owners are held captive by. Every time the mechanic leans over and instinctively places his elbow on it, a $200 bill flashes before my eyes. I've added a zip tie to help support the woefully under-equipped lone mounting bolt. And even though mine is one of the fortunate few that isn't leaking yet, it's cloudy to the point that it's very difficult to tell what the coolant level is without popping the cap. And even that doesn't tell you much because the design is so poor, the shallow part where the cap is gives you almost no line of sight to the actual reservoir. To add insult to injury, it takes up a good 3x as much horizontal space as is reasonable for its capacity. As far as I can tell from fairly extensive searches of the forums, no one has found a way to cleanly replace it due to how integrated into the radiator setup it is. All in all, it's easily one of the dumbest engineered things I've ever seen. I'd be doing the car a huge favor in ditching it!

 

the stock supra radiators have the trans cooler, but not sure if any of the aftermarket ones do. honestly I prefer to separate coolers ones on a setup like that, no chance of mixing if one goes out. all it takes is a little coolant to get into that trans fluid and not notice it then you will be looking at changing the transmission (there are a few threads on the stock one breaking and that happening).

If it was my SC4, I would get a ls400 clutch fan setup, and maybe the shroud, supra radiator, seperate trans cooler zip tie it down there somewhere, and see if it will all work together.
maybe even a ls400 radiator might fit nicely if you aren't stuck on the aftermarket ones.

I have never used a radiator that had no fan. in our cars it would overheat in a fast minute if you were at operating temp, I have only ever had the fan off when testing the motor after a build-rebuild and even then you never let it run that long cause you don't want it to overheat.

if there is a special car that has large vents like that, I can almost assure you the owner would tell you that you must be moving with the engine on to get air to pass over the radiator. those type of cars you generally shut down if you are not moving. like air cooled motorcycles or those old MB's, you don't ever idle those things, if you are going to be stopped for a good amount of time you turn it off. Maybe I haven't seen the special ones you are talking about but I know our cars would not last very long without the radiator fan.

 

Man, I swear I saw something about one of the current production cars like the Corvette being fanless, but I can't find anything now, so maybe I dreamed it. In lieu of anything tangible on my part, I guess I'll have to take your word for it!

I looked up clutch fans to familiarize myself with the concept, and it sounds perfect if I get the hood vent done. The waterpump would engage the clutch and turn the fan at idle and low speeds, then disengage it for more efficient engine operation (although, the stock hydro fan is supposedly very efficient) when the vent is pulling air through.

However, I'm finding myself confused by seemingly contradictory info about the LS400's setup. Some stuff indicates that it combines the clutch fan with electric fans, which sort of brings me back to square one in terms of choosing between two evils, while other stuff says it's purely mechanical and connected to the water pump. I'm not sure if that's a pre/post-'94 thing?

The smart thing to do would probably be absolutely nothing, as long as the cooling system is working properly.

 

the hydro setup on the sc400 is the best sort of cooling system you can have, at least its the most advanced, it can provide variable cooling for all engine conditions.
the ls400 setup resembles the sc300 and supra regular clutch fan setup. sometimes they will have a small auxilary fan for the trans cooler which may be what you are talking about.
it does not draw nearly as much as 2 large radiator fans and majority of the cooling is mechanical via the clutch fan, I thought it always spins didn't know it stops at any point are you sure about that.
The clutch fan does rob a touch of power as its a mechanical fan, but its more reliable and not much that can break where a hydro setup is very complicated as you said and prone to people leaning on it and cracking the reservoir.... or maybe you can build a new type of reservoir somehow, not sure.