Rear Mounted Radiator??? Any long time successes?

[rhowde]

I've spent months scouring this and a couple of other websites for anyone successfully running a rear mounted radiator over a period of time. I've yet to find any one. I'd prefer running an above-the-transaxle setup if possible. If you have this type of cooling setup, could you share your experiences and possibly pics? I'd like to use the car as a summer daily driver, so a solid low maintenance system is a must.

Thanks in advance for your feedback!

-Rob

[883]

Lots of Bajas and rails running wing type or rear mounts successfully, but...cut up or open bodies.

BajaWes on Aussieveedubbers has been running the over the trans mount for a long time with a V6. But, once again, cut up baja body and no deck lid, lots of ground clearance.

I've seen many attempts at doing this on full bodied cars. Many failures reported, some have switched over to front mount, and some just disappeard before reporting success/failure.

I imagine the concensus will be to front mount in a full bodied street car.

[Ol'fogasaurus]

What is the use going to be; e.g., street, race, Baja, etc. and what is the engine? I think there are several here in long process builds.

[rhowde]

Its a street car running a 12a, soon to be a 13b TT, so heat is an issue. I'm currently running a rear mounted cherokee radiator, but it starts to overheat on the freeway. I'm torn between purchasing an aluminum racing radiator that is guaranteed to support 650 HP in a stock application, or switch to a front mounted setup. Obviously, I'd rather stick with rear mount as all the work has been done, but if I cant confirm anyone has conquered this, I'll have no choice but to change.

[xoo00oox]

I ran one for years, it can be done but everyone will tell you it won't work. Even when I would drive it an 1 1/2 hour to a car show, people would look all over it and tell me it would overheat. This had the same coolant in it for years.

http://www.thesamba.com/vw/forum/viewto ... hlight=wbx


The transmission had to come out because of a leak and I had a 2.2 subaru with a Vanagon Kennedy adapter plate on it just hanging around so I did this....

http://www.shoptalkforums.com/viewtopic ... 9&t=143859



Andrew-

[883]

aluminum racing radiator that is guaranteed to support 650 HP in a stock application

I wouldn't buy that yet.

The Cherokee rad should have enough capacity. It sounds like you are lacking airflow.

If you can post some pics of your set up, maybe you can solicit some ideas to improve the flow?


xoo - I only saw one pic of your set up when I was researching, and no description. (I don't get over to TOS much) I guessed, by the one pic, that it would overheat. Although, the hot and cold sides are well seperated/sealed. Very important to prevent re-circulating hot air.
Diggin the curved rad thing too, can't wait to see how that works.

[rhowde]

Andrew, I did check out both of your setups. Funny thing is I didnt realize they were the same car. I had considered trying to copy your system, but then realized that it still wont work as the 13b I plan on switching to is way too tall. My 12a might even be. Plus the heat the rotarys put out is higher than a suby.

[Ol'fogasaurus]

Have you tried the cotton tuff trick yet and having it video'd as you drive? An old trick that does work most of the time. It should show you air flow and if you have any dead air areas.

[rhowde]

Ol'fogasaurus, I used a variant of that. It seemed to be flowing in the correct direction, but I'm not sure if it is enough. It works fine now that the outside temperature is cooler, but when things warm up, so do my coolant temps.

[Ol'fogasaurus]

Is your radiator laying flat by any chance? I do off-road stuff so I pay more attention to that than street stuff but a couple of things I have found out: radiators do not work well if the direction of the air flow has to change in order to go through the fins. There were a couple of rails that I knew of years ago who tried to mount the radiator side ways in the chassis. That didn't work well so they tried two radiators mounted sideways and not much was gained from that.

Also, watch for dead air spaces/places in front or in the rear of the radiator where the airflow is disturbed and you get a airflow roll. No matter what you do, if there is a dead air space, and I don't know all of the reasons for them; some times it is being mounted too low or two close to an object but air flow can be drastically reduced or the effect of air flow can be negated. Sometimes the movement of the radiator only a couple of inches can make a difference. One of the reasons for a good yarn test while moving at different speeds.

The old station wagons got to the point that they put an air deflector that changed air direction down to break up the roll in back of the wagon which caused the rear window to get so dirty that you could not see out of it.

Anyway, for what it is worth!

[spud]

I had mine enclosed in the back for 2+ years, depended on 2 10 inch fans that would run on low speed all the time after the engine got to operating temp and on high only after sitting in traffic or serious off-roading (1st gear and mostly floored). I never had the car over heat past 220 (one day I was sitting in Serria Vista, Arizona traffic to get that high) with the fans on, even on the freeway at 70 mph. Its an all copper Jeep Cherokee rad as well. I now have it attached to a roof rack above the rear window because I wanted to enclose the space in front of the motor for noise reduction. Fans have not come on in city traffic all summer and temps run at 175 at the thermostat housing. The return hose from the radiator is cold enough to hold on to indefinitely at engine operating temps. I definitely could get away with a smaller rad. I have pictures of that build on previous posts. My system works so nice I don't even think about it any more.

If I was starting all over. I would have got an after market Honda Civic Rad, placed it sideways on the rear window shelf, and would have used a large squirrel cage blower similar to a VW fan. They will pull massive amounts of air but can be pricey. The fan would still have to run all the time but it would make for a compact cooling system and I could have an AC setup that would work with it. The air pressure from the squirrel cage fan could also be ducted into the cars factory heater system using simple cable operated valves.

[rhowde]

Spud,

Was that with the scoops on the sides? If so, that would have made a huge difference. If not, I may be in luck.

[spud]

It had large side scoops about 11 inches high and 4 inches out. The body had portals through the sides about 8 inches high and 4 inches wide. They blocked the view from the rear view mirrors.

[rhowde]

That wont work on my street bug. I'm about ready to give up hope on a rear mount.

[E_bug]

I have seen a guy over here that hid the radiator inside the fan housing and had the alt/gen spin a big fan. It looked stealth and he said it worked fine.
I dont remember the link though.
Maybe somebody does and will chime in