Topic: Rear-mounted radiator

Show them to me.

I need advice, common pitfalls/designs, scoops, that kind of stuff.

K Car Stalker

Re: Rear-mounted radiator

I know the NJMP bug has a radiator in the front, but coolant lines that run to the motor in the back.  May not be the solution your looking for, but an option.

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Re: Rear-mounted radiator

duct the flow in, duct the flow out.
high pressure to low pressure.

Highly dependent on average speed you going, and average power you using.
math really comes down to fuel/hr you using which 1/3 ends up as heat
average speed you going, so lap time around the track
how much air in volume it takes to heat it up from ambient to engine temp
divide that by average speed, and you get duct size in free air.
assume 85%? maybe. divide that area by 0.85 and you get good size of the duct you need.

Or could use the original grill area that the car had for the radiator and go from there.

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Re: Rear-mounted radiator

I'm trying to avoid running the radiator upfront. I have a sealed (no cap) radiator and a pressurized expansion tank, so it's much easier to place it somewhere in the trunk. Power is laughable, my fuel burn is somewhere around 2.5gph.

K Car Stalker

Re: Rear-mounted radiator

In the simplest of terms, you need high pressure on one side and low pressure on the other, and no where for air to leak around it.

What body shape is the car?

I've seen trunk mounted radiators in sedans. Usually there is a low pressure area behind the trunk, so you can cut out large holes from the trunk, put the radiator there, and then duct in air from the roofline. Seal it all well so that air goes through the radiator, not around it, not into pressurizing the trunk, but through the radiator.

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6 (edited by jrbe 2017-05-10 06:35 PM)

Re: Rear-mounted radiator

A vacuum evacuation / "coolant" fill setup for that type of system will be your best friend.

Consider an expansion tank (European cars typically use them) to give some place for air to go. At the very least I think you'll need a bleeder up high on the radiator to get air out.

Ducting isn't necessarily straight forward. What you think are high or low pressure areas might not be far enough apart to get good flow without really strong fans. Between the tail lights is usually a good low pressure area to dump the hot air out. The roof should be a high pressure area. Behind the front doors on the sides are probably neutral but with scoops you can grab air.

There are a bunch of mid /rear engine cars that have rear radiators to look at for ideas.

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?

Re: Rear-mounted radiator

Car is C3 Corvette-shaped. I'm trying to preserve the body lines but I'm considering making holes on top of the bumper cover and running a spoiler right above it to create vacuum.

I thought of ducting air from all the way at the front, but the trans tunnel is like 4" in diameter at the end.

Any point scooping up air in front of the rear wheels? I can attach some sheet metal to guide the air in. My ground clearance is like 7-8 inches.

K Car Stalker

Re: Rear-mounted radiator

Why not as a wing / spoiler?

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Re: Rear-mounted radiator

firegremlin wrote:

Car is C3 Corvette-shaped. I'm trying to preserve the body lines but I'm considering making holes on top of the bumper cover and running a spoiler right above it to create vacuum.

I thought of ducting air from all the way at the front, but the trans tunnel is like 4" in diameter at the end.

Any point scooping up air in front of the rear wheels? I can attach some sheet metal to guide the air in. My ground clearance is like 7-8 inches.

So is it a corvette? or an Opel? could you put it behind the seat? that way all the air coming in around the cockpit would pass thru the rad...of course you'd need a big ash fan to push it and vent the hot air out the back.

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Re: Rear-mounted radiator

Watch and learn:

https://www.youtube.com/watch?v=XuHIemMF4kY

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Re: Rear-mounted radiator

I didn't get any pictures, but I was at a shop this morning and saw a Lotus with a radiator mounted almost horizontally in the rear. They had a scoop under the car to force air through it  and a duct out the back of the car.

Everybody grab your brooms, it's shenanigans!

Re: Rear-mounted radiator

mid engined renault clio - Google Search
https://www.google.com/search?q=mid+eng … &dpr=4

-Killer B's (as in rally) '84 4000Q 4.2V8. Audis never win?

Re: Rear-mounted radiator

firegremlin wrote:

Car is C3 Corvette-shaped. I'm trying to preserve the body lines but I'm considering making holes on top of the bumper cover and running a spoiler right above it to create vacuum.

I thought of ducting air from all the way at the front, but the trans tunnel is like 4" in diameter at the end.

Any point scooping up air in front of the rear wheels? I can attach some sheet metal to guide the air in. My ground clearance is like 7-8 inches.

IT'S HAPPENING!

My advice would be roof scoop intake and outlet to the underbody.

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Team FinalGear

14 (edited by firegremlin 2017-05-15 12:32 PM)

Re: Rear-mounted radiator

I've realized that my fuel filler neck would have to go way forward of the factory position, so my airflow can get split between OEM filler opening (yuge) and cut-out license plate area. Now just need some creative air pickups for the inbound side.

Using a 944 radiator that has a remote pressurized coolant tank, which sadly means no over-the-top mounting.

K Car Stalker

Re: Rear-mounted radiator

The remote pressurized coolant tank means that it needs it be the highest point shock can be on the roof next to/above the radiator. ..
Alternatively you can get a radiator with a filler cap and ditch the pressurized tank. You just need to make sure there is good venting of the cooling lines and slope up to the radiator, to ensure the elimination of air bubbles.

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Re: Rear-mounted radiator

We do it successfully in the mid-engine Chevette.    Same reason.    I didn't want to run coolant lines all the way from one end of the car to the other.

We have no natural airflow, we depend 100% on the 2 electric fans.    Oversize your radiator, and get some powerful (and reliable) electric fans.


I'd include a photo, but this forum doesn't look like it hosts images.   I'm at work, with no way to upload an image to any file-sharing site.   I'll post one when i get a chance.

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Re: Rear-mounted radiator

ah-ha,   Found one on Judge Phil's Uber Gallery

http://www.murileemartin.com/UG/LNHF15/ … _0078.html

The Defeat Device - Mid-engine 1979 Chevette - Class C Winner - GP Du Lac Chargoggagoggmanchauggagoggchaubunagungamaugg
New England Long Winter Build Award - 2015
IOE Winner, Loudon Annoying 2011, Judges Choice - Loudon Annoying 2012
Class C & Least Horrible Yank Tank winner - Boston Tow Party & Overhead Cam Bake 2011

Re: Rear-mounted radiator

Speaking of this, just wondering if it goes against the rules to have a rear mounted intercooler. But it does have an expansion bottle and relief valve.

I would be mounted on the roll cage behind the driver 18".

Re: Rear-mounted radiator

mike944 wrote:

We have no natural airflow, we depend 100% on the 2 electric fans.    Oversize your radiator, and get some powerful (and reliable) electric fans.

If it's good enough for Porsche, it's good enough for Lemons.

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2016 CMP Fall South "Heroic Fix" Winner

Re: Rear-mounted radiator

Jbquickeljr wrote:

Speaking of this, just wondering if it goes against the rules to have a rear mounted intercooler. But it does have an expansion bottle and relief valve.

I would be mounted on the roll cage behind the driver 18".

Fluids in the driver's compartment are bad juju. So no air/water intercooler. Air/air shouldn't be a big deal.

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Team FinalGear