Radiators to the back, what do you think..? (1 Viewer)

[middlecalf]

make sure you put in reversable fans and switch, eliminates the need for a rear heater 383's get that hot?

 

[GarageRat]

So wait...a 383 with a dry sump setup, which I take to imply that it has quite a few other goodies given how usually a dry sump follows extensive upgrades, but you kinda cheap out on the cage? Guess I don't understand your line of thinking with this.

As far as the radiator goes, looks like it's already ducted so let's make it so a failure does not result in you getting covered in hot coolant. If it was me, I'd take probably 18 gauge sheetmetal and form a duct/surround for the radiator to direct the air with a secondary benefit of containing the radiator seperately from the passenger compartment.

 

[FJforty]

Maybe you should have left the radiator in the front and put the engine in the back. Just kiddin.. I just want it to work for you. I think some engineering might be needed. If you are in an incline/decline position fluid will pool to one end. You might need a high temp aux. water pump to keep things working and will certainly want to keep the system full. Radiator cap might vent when going uphill. Good luck.

 

[Bret]

Depending on the electric draw of the fans your electric system may need a bit of beef as well. Some of those fans pull 70 amps on start-up and 20-ish amps running (each). Getting enough airflow at speed would be my next concern. Would definately want to consider the "what-if's" for crashes, rolls, etc.

 

[rusty_tlc]

Someone on here put a 12 cylinder Jaguar engine in a 40 and had room for the radiator. What are you planning on running for a motor?

The engine is only half the drive train.
An auto transmission and dual t-cases would be long enough to warrant moving even a SBC engine forward to keep the rear drive shaft from getting to short.

 

[Moe R]

You'll probably have a few kinks to work out. But, I think it will look cool when finished. Put a biesel on the back and people won't know if your comming or going. Good luck.

 

[Downey]

I'd take a lesson from Baja racers who put the radiator in back:
1. In the classes where they do not have to run a windshield, they do get enough air through the cab to reach the radiator.
2. In the classes where they have to retain the windshield, the massive air scoop they have to build over the roof just plain looks hideous. It has to be the entire width of the vehicle, and stick up above the roof atleast 12".

 

[mrjay2u]

Keep the pics coming, I am intrested on how this turns out.

 

[fieldsken1]

well let me be the first to say bad idea. the air that is going down the side will be pushed out from the side as soon as it hits the front of the fj. you will have to build something that sticks out from the side to direct the air flow inward like a scoop. putting big enough fans on will work but does take alot of amps. heres a picture of what i did. i am cooling down a big motor also. dry sump of course. if you look at the second picture you can see the radiator just behind the seats it does get air that way also and it helps. you can even see the scoop on the inside on the roof look hard

 

[Micks-Troopy]

don’t think just a scoop on each side would do it either as the height of the scoop will be the maximum intake, would need fins ranging in height too see each slot get a portion of air, but that’s still going to limit air flow across the radiator.

 

[Trollhole]

I think it's a cool idea.

Nobody has any idea what size radiator your running in the back and if it covers the whole tailgate area I'd say that is a big radiator.

Since you said you were covering the top and insides with sheet metal you won't have any issue with fluid geting on you in a rollover. No more than if it was in the front of the vehicle.

The pipes running back to the radiator ought to provide even more cooling. Some fans that move a good amount of air and I'd think you would be okay. Only time will tell.

 

[nordwind]

I made a kind of drawing,
Yellow is the radiator, yellow / pink the Electric fans
this triangle in the center is a storage box,
I want to use a cross flow aluminum radiator
Width 36.00 in. Height 12.00 in. Thickness 3.00 in.
I think, after reading all the reply, (FJforty) a inlieniee water pump near to the radiator is a good thing.

 

[Mtrunner]

I hope it turns out cause I want to see pics of this in action.

Good luck.

 

[Bret]

Seems if I remember right the air has a tendency to come into the vehicle from the back. That may change if you have a hard-top or soft-top etc. That may make it harder for the fans to push the air through that way.

 

[3rides]

I would mount the fans flat to the rad otherwise a lot of air will be deflected to flow back out the sides. Also I would close off the rearmost 10" or so of each side vent to prevent the same thing or make a scoop that covers the back 10" or so. Air is going to have a tendancy to "spill out" of that portion. The air in front of the fan is going to be turbulent and reduce air flowing in from the sides, so anything you can do to keep it in there is going to help (ie: scoops or closed off). In order to help create suction to assist the air through the radiator you want the surface area of the opening behid the rad to be larger than that of the combined surface of the intakes (just to give you a square footage to measure for).

Thats my thoughts on the design. Definitely without question mount the fans directly to the rad, maybe even on the back of the rad. On front mounted radiators a pulling fan is much more efficient than a pusher. This is well established so don't see how it would be any different.

 

[Bill McC]

Seems if I remember right the air has a tendency to come into the vehicle from the back. That may change if you have a hard-top or soft-top etc. That may make it harder for the fans to push the air through that way.

He has an excellent point here. There will be higher pressure to the rear of the vehicle and low pressure on the side. Maybe side vents pointing back and fans pulling from the rear.

 

[rusty_tlc]

He has an excellent point here. There will be higher pressure to the rear of the vehicle and low pressure on the side. Maybe side vents pointing back and fans pulling from the rear.

I think the vortex behind a car is formed by laminar flow of air down the sides and over the top. With the louvers on the side it won't be nearly as pronounced.

Besides we aren't talking Formula one here. An FJ40 can only go so fast.

 

[FJforty]

You might take a look at blowers instead of fans. They can create more pressure/flow. If you have a few extra bucks look into brushless blowers. They will last almost forever and are quiet relative to a blade fan.

 

[malcb]

Interesting, rad in the back is seen sometimes in the UK, mostly because of mud clogging the radiator and causing overheating. Modified Bowler Land Rovers have rear rads for one.

Surprised no one has referenced Matt Mcinnes, he has a rad in the rear and the front ;p. IH8MUD.com - View Single Post - 2F + 3F-E = 2F-ETI Into My FJ40 (Turbo & Intercooler)

If I ever supercharge a 2F I have thought it might be better to put the rad in the back and an intercooler across the front of the engine bay, do have some concerns about coolant pipes and a hot rad behind my head so your idea of keeping the rad low and covered has a plus.

 

[malcb]

I think the vortex behind a car is formed by laminar flow of air down the sides and over the top. With the louvers on the side it won't be nearly as pronounced.

Besides we aren't talking Formula one here. An FJ40 can only go so fast.

Laminar flow and FJ40 - doubt those words appear in the same post often!

Bit like FJ45 and spoiler!