So basically I made the decision of investing in a 1987 MK3 Supra with an 350 small block engine swap. The current radiator is not cutting it and the vehicle overheats after 10 miles of driving when its less than 40 degrees Fahrenheit out. Any hotter than that and it's not even worth trying to drive it.

In a perfect world, I would actually have money for a radiator that would fit properly (a 3 core radiator from a 76 Nova). However I don't have money as I'm a teenager.

I have a wrecked 03 GMC Envoy with the Vortec 4200 engine. My plan is to pull the radiator from it and try to put it in the Supra. It'll obviously take some fabrication to make it to fit. However, the radiator will have to be on its side for it to fit. Below are the dimensions.

Core Dimensions: 26.25 x 17 x 1.25 in.
Core Material: Aluminum
Engine Oil Cooler: No
Inlet Size: 1.31 in.
Number of Rows: 1
Outlet Size: 1.56 in.

17.94 x 27.06 x 1 in. core size
1.31 in. inlet size, 1.56 in. outlet size
2.25 x 27.38 in. top header, 2.25 x 27.17 in. bottom header
Top right inlet location and bottom left outlet location

The big question is: Will the radiator be able to operate properly when on its side?

Do you have any tips for putting it in?

One plan I have is to relocate the battery to the trunk(I haven't done it before, but I've heard of people doing it to make room).

  • Can you attach a picture or a drawing of how it is going to fit, especially relative to air flows?
    – Kromster
    Commented Feb 17, 2014 at 7:40
  • @KromStern youtube.com/watch?v=UAwvvmvcExM Will this help?
    – Alec
    Commented Feb 17, 2014 at 17:16
  • I'd recommend that you take a still picture (or two) from your youtube video to illustrate the situation as well. It helps those of us that can't reach youtube right now.
    – Bob Cross
    Commented Feb 18, 2014 at 12:55
  • I'm just going to save up and buy a high quality racing radiator and fans as it seems like the best option, thank you everyone for your help!
    – Alec
    Commented Feb 19, 2014 at 4:00
  • Get professional advice first. It may save you money. Commented Feb 19, 2014 at 15:17

2 Answers 2


Yes, it will. However, your biggest concern is going to be getting enough air flowing over it. Do yourself a favour and go look at the engine bay of a 200x model Subary Impreza WRX. The intercooler is mounted flat on the top of the engine and the characteristic scoop forces air onto it to cool the intake air. The same type of thing might work for your radiator (which is basically an intercooler for water).

But if it were my car, I'd rather opt for two or more smaller radiators fitted behind the front bumper. Again, have a look at a regular turbo car's setup: the intercooler is placed below the radiator, behind the front bumper where lots and lots of high-speed air can flow over it. I'd keep the current radiator and have a second one mounted where the intercooler would go. You can call it a "two-stage cooling setup" and send me royalties or something ;)

Update: you may also want to double-check whether the current radiator is actually working properly. If there's a blockage somewhere, it may already explain a lot of your heat problems. It may end up saving you lots of money if it turns out you simply need to have your radiator flushed and filled with some new coolant/H20. But I wouldn't count on it. I just mention it for the sake of completeness.

  • Thank you for your reply. I don't want to quite pick an answer yet as I'm still doing research myself. I'll get back to you though.
    – Alec
    Commented Feb 17, 2014 at 16:32
  • Also watch this and tell me if you have any more suggestions based on under the hood: youtube.com/watch?v=UAwvvmvcExM
    – Alec
    Commented Feb 17, 2014 at 19:03
  • That's a mighty big radiator you've got in there already. I'd say go to a performance shop and ask their opinion. Maybe have the car towed or something or show them pics of your engine bay and front bumper. Maybe the problem is just that you don't have enough air flow and a different front bumper could do the trick. Also, have someone test your fan. Commented Feb 18, 2014 at 7:29

The bigger question here is, what are you actually gaining? The dimensions of the Envoy radiator is only marginally bigger than the current one. Your question, "Will it work?" is rather irrelevant. The pertinent question here should be, "Will it work better?" ... The answer to this is most probably No. You need to find another radiator which is the same dimensions as the current radiator (height and width) and have it thicker, like two or three cores thick. I know you said you are a student and cannot afford this, but obviously you are not driving it currently. If you cannot enjoy the car, what is the use. An easy way to save money on this is by going to a pull-a-part yard where you can measure out what might work, look for inlet/outlet locations, pull it yourself, and save a huge amount of money.

While Juann's suggestion of a secondary radiator is not without merit, it would be better to figure out what is wrong in the first place. His update starts with one solution, but there are other things you should be looking at.

First, are you sure your thermostat is up to snuff and working correctly? A closed thermostat would exhibit the same type of overheating. Can you put a lower temp thermostat in the car (and I know the answer to this is yes). Standard temp stat for the 350 is like 195F. Put a 180F one in there and see how that works you.

Another thing to look at is if there is a shroud around the fan? This is so commonly overlooked and is pretty easy to fix with some thin sheet metal or even an electric fan with its own shroud. The reason the shroud is important is, without it, the air mainly just whirls around the fan and has no direction. With it, the air is forcefully pulled through the radiator as it should be.

Speaking of the fan, is it working correctly? If a clutch fan, is the clutch portion locking up?

There are a lot of things you could be doing before you change out the radiator. To me it seems you'd be doing a lot of work for little gain.

  • What does the thermostat look like? Where can I find it on the engine? Or are you talking about the gauge?
    – Alec
    Commented Feb 17, 2014 at 22:45
  • The thermostat housing looks like this picture. Just underneath it (after removing two bolts) the thermostat looks like this. It is located front and center of your intake manifold. The upper radiator hose attaches to the neck of the housing. Commented Feb 17, 2014 at 23:19
  • I just asked the previous owner and he said "It has no thermostat"
    – Alec
    Commented Feb 17, 2014 at 23:23
  • I hate to say it, but that is a really stupid way of trying to fix overheating issues. It really solves nothing, as I am sure you are well aware. At this point, the Envoy radiator might even be a good idea to try, as I would bet the one which is in it right now is plugged. Actually fixing it would require having the tubes rodded, which is not cheap. I would still highly suggest getting a thicker radiator as I described above. Another thought is to look on Craig's List for someone parting out a SBC car and see how cheaply you could get a radiator that way. Commented Feb 17, 2014 at 23:31
  • If you look in the video the fan isn't too great looking and only covers half of the radiator. Would two 14" racing fans do the trick? A friend suggested putting racing fans on the radiator. I found these on Amazon amazon.com/dp/B00H29LQHS/…
    – Alec
    Commented Feb 18, 2014 at 0:35

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