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Author Topic: Mounting radiators in the back.......  (Read 3268 times)

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Doughnutter

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Mounting radiators in the back.......
« on: July 26, 2008, 00:03:21 AM »
As some of you know i have a 3 door drift car that I bought off Pax. When I bought the car he explained his plans to mount the rad in the rear of the car. The reason for this is that the rad is the weakspot on a Sierra drift car. When you get it wrong and end up with a cone under the front of the car it can split the rad, usually where the mountung points are on the plastic bits. This has caused me trouble before at Santa Pod dift days, when I've had to go hunting local scrappys when I should be drifting! I would also like to compete next year in some competitions and they have a 5 min rule. This means if you have car trouble you get 5 mins to repair it and get back to the start line or your out. end of, no flexibility. I can change a rad in five mins now but I can't let the block cool enough to put cold water and bleed it up in the time. I'm also considering a lightweight ali plate from the front end going under the crossmember to protect the rack and associated plumbing from large motorway style cones that are sometimes used at tracks.

The car has had 2 air vents put into the rear 1/4's which will allow some airflow to the rad fans. I'm considering mounting 2 rads in the back, although I'd prefer to have just one to save some weight but I think due to the reduced amount of airflow with having them in the back it may be nessasary to have a pair with 2 fans on each. I think I'd use twinky rads and fans mounted on a lightweight frame poss alli. Any ideas on rad types to use maybe an alternative bigger single rad? Or one twinky one may just be enough?

To pipe the water front to back I was intending on using alli pipe, same size as the input and output pipes on the rads. I originally considered runnin the pipe's under the car so the cool air passing them would help cool the water even more but I have concerns about the possibility of damaging the pipes with the low ground clearance. I think they will have to run down the inner sills and through the bulkhead. Another idea a mate suggested was to run them through the transmission tunnel but as I have a centre exit exhaust that sits under there I'm thinking that the temps will be raised from this to a level thats too high and it leaves the chance of damaging them if the prop gives up. I think the design of the exhaust may also be a contributing factor in the gearbox failure i've had with the oil getting very hot due to the close proximity of the silencer, but thats another thing to consider later, i'll see how the hybrid replacement for the type 9 gets on first... I'd also like to route them so if I deceide to go twin turbo in the future I don't have to move them again. Is there any ideas? Also should I use the alli pipe or is there another alternative, bearing in mind reliabilty is the main concern, followed by the fact I don't want to get hot water spurting all over me if they burst    

Pump wise I'm thinking of an electric assister pump. I know that in some mid engined cars with front rad they use the standard pumps, eg Lotus elise with rover / honda power use the same pump as the would in a 45 / civic for example and porsches use twin rads with one not too huge water pump. I think thought that for reliability and to save expensive rebuild costs on the BOA engine i'd rather play safe. Is there a car that I may be able to find in the braekers with a electric pump?

Is it worth removing the spare wheel well and plating it flat, mounting the rad flat above or maybe even below it with the fans above blowing downwards? Would there be enough airflow this way? The lower I can keep all the weight the better to keep centre of gravity low. Would having the rad in the back of the car, cutting floorpan parts out make the rear end unstable due to wind turbulance or something at high straight line speed, bearing in mind with the new box with the long 5th gear it should max out pretty high  

Anyone got any veiws / ideas on this project? any input would be appreciated  




Offline JFB Tech

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Mounting radiators in the back.......
« Reply #1 on: July 26, 2008, 00:35:03 AM »
You could always try a Cossie rad mounted high up in the front, that way it's less likely to get damaged if you take out a cone.  These must be more efficient than the standard Sierra rad if they can cool a 2 ltr turbo lump OK.  Mounting the rad in the back will put a lot more strain on the water pump, take a long time to warm up fully and you will be totally reliant on fans for the airflow.  Hell of a lot more potential to go wrong not to mention a sh!t load of work.
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Offline capri v8 driver

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Mounting radiators in the back.......
« Reply #2 on: July 26, 2008, 08:49:31 AM »
dont hit any thing.

mounting the radiator in the back is something i have seen whit stock car's, but its alote off work, just like JFB already said. there are no elec waterpump's on production car's that have enough flow you need to pump the water around, so this means going aftermarked=$$$$$

in your case, i would make a protection (a steel brace) in front off the radiator and mounth the radiator on flexible mountings. you could mount the radiaror in a angle and lower into the engine bay to lower centre of gravity.

greetz paul.

capri v8 driver.
greetz Paul.

Capri V8 Driver.

IansSaph

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Mounting radiators in the back.......
« Reply #3 on: July 26, 2008, 09:44:16 AM »
yep, cossy rad mounted high and a custom sump guard to cover the area fron the frontof the bumper to the x member.

Doughnutter

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Mounting radiators in the back.......
« Reply #4 on: July 26, 2008, 10:15:04 AM »
Surely the cosy rad is the same size as a normal sierra twink rad as it fits to the same mount points so its has to be the same width? Or am I missing someting? Anyone got a cosy rad they could measure please, lenght, height, depth and input / output pipe size please and any other info eg core sizes / extra cores compared to standard please?

popuptoaster

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Mounting radiators in the back.......
« Reply #5 on: July 26, 2008, 11:37:07 AM »
i'd fit something smaller and thicker and build it some crash bars, V6 mk2 granny rad is reasonably compact, much more rigid than a sierra rad and keeps my 24v cortina cool easily.

Offline Mik

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Mounting radiators in the back.......
« Reply #6 on: July 26, 2008, 14:33:44 PM »
The main reason for shifting the rad to the back is weight transfer, aiding the vehicle to turn in faster by reducing weight in front of the front wheels. . The Sierra has a very light rear end when stripped so this will help the balance dynamics of the chassis.

However, this is ideal in a circuit car where high speed cornering is a major factor but it may not be ideal in a car that you want to go sideways for most of its time on track. The only way to find out if you like extra weight at the back end is to test with a weight of 30 to 50 KGs in your spare wheel well. Bags of strapped down sand will do. This will increase the pendulum effect on the back end when it steps out of line. This may make it easier to contol or visa versa. You need to test it out. Hard times eh.

If you like the weight then go ahead with the conversion. A single large rad will suffice for cooling with either twin standard or aftermarket units used. You will need fairly large vents on the quarters to feed this but not huge. The fans will suck enough air when stationary (override switch preferable) and once moving all should be good anyway. The air can be vented through the the licence plate appature wth mesh and also through the spare wheel well at the rear and vent the bumper to suit. Not the best looking idea though. This is trail by fire and testing is needed. The whole system needs to be boxed in to maximise the airflow through the rad.

The aerodynamic effect of a rear vent is minimal at best and you'll not notice the differance as you're venting a small quantity of high pressure air into a large low pressure void. The air effects on your spoiler will be the same. If you still want to clean up the airflow you could fit a floorpan diffuser.

The pipes can be made from either alu or copper. I've seen setups with domestic copper pipe used to very good effect but it looks shite. For ulimate protection, run the pipes inside the car with either fibreglass tape or boxing to reduce the cabin temps.

Not fully sure on this one but commercial motors must use electric waterpumps somewhere.






Or you could just fit a big metal plate under the rad.  

Mik

Doughnutter

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Mounting radiators in the back.......
« Reply #7 on: July 26, 2008, 14:59:29 PM »
Thankyou all for taking the time to reply  

@ 'JFB Tech'

Don't mind a little bit of work, in fact I enjoy it    

As for taking a long time to heat up... am I right in thinking that until the thermostat opens then the water doesn't go to the rad? so start heat up time will stay the same, the only difference being that when the thermostat does open the drop in temp could be a little more than normal as there would be more cold water contained in the new system.


 @ capri v8 driver'

I hope I never hit anything again Paul, but unfortunately I'm a beginner and even the pros fuck up from time to time  

don't think it will sit any lower, thats part of the prob, not a lot of clearance between rad and floor and those motorway cones have massive solid base plate that can bend / break rads / alli easily, especially when you misjudge the clipping point on a 3rd or 4th gear entry and end up a foot or 2 the wrong side of the line you want and end up eating a cone    Steel brace is adding weigh were I least want it. looking at reducing front weight and get a better weight distribution, I've already got a heavy big 24v up front, more weight on the nose is not going to help  

@ IansSaph'


do you know just how the cossie rad is better? is it deeper? more cores?    Am thinking of a skid pan plate but as you can see from the pics its going to be hard to make a lightweight one in the right shape with sufficiant strength to take a motorway cone hitting it any where between 10 and 100mph

@ 'popuptoaster'
Thicker, shorter rad is an option, would certainly raise ground clearance andmay make getting a skid plate easier as it wouldn't have to come down, under bottom or rad and then back up towards the crossmember  

@ 'Mik'   Not the main reason but certainly a close second on the list after maintaining the rad working in a track day / comp    Spot bollock on though with the idea  

Looks like a trip to Wickes builders depot on the way to Santa Pod drift day on the 13th of Aug then  

Deffinatley some food for thought there. Glad you think the stability won't be affected at speed. Could you describe briefly what a floorpan diffuser looks like pls?  

Yeah I rekon if I look hard enough I'll find a electric pump someware for the right money,


BIG metal plate ?    Last option on the list  


Again thanks every one for the input. Some pics of....

Ground clearance between bottom or rad and floor...

« Last Edit: July 26, 2008, 20:05:58 PM by Doughnutter »

Offline capri v8 driver

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Mounting radiators in the back.......
« Reply #8 on: July 26, 2008, 21:38:15 PM »
Quote from: Doughnutter

 @ capri v8 driver'

I hope I never hit anything again Paul, but unfortunately I'm a beginner and even the pros fuck up from time to time  

don't think it will sit any lower, thats part of the prob, not a lot of clearance between rad and floor and those motorway cones have massive solid base plate that can bend / break rads / alli easily, especially when you misjudge the clipping point on a 3rd or 4th gear entry and end up a foot or 2 the wrong side of the line you want and end up eating a cone    Steel brace is adding weigh were I least want it. looking at reducing front weight and get a better weight distribution, I've already got a heavy big 24v up front, more weight on the nose is not going to help  


i was just kidding  

to make thing's easyer for you, take a look at a vw siroco or audi 80 or a4 diesel radiator's. they are lower in height.

where do you have the battery? you could move that one to the boot, if you haven't done that already.

greetz paul.

capri v8 driver.
greetz Paul.

Capri V8 Driver.

Offline Mik

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Mounting radiators in the back.......
« Reply #9 on: July 26, 2008, 21:49:12 PM »
The aerodynamic diffusers work by cleaning the airflow so that it passes the car with the minimum of effort. most cars now come with basic setups on the front in the guise of an engine undertray. This reduces the amount air from under the car entering the engine bay as this increases the engine bay pressures and reduces the airflow through the rad.

Anyway, at the back the same principal applies. Place a smooth bellypan under the rear axle to the rear bumper to smooth the flow from the rear of the car. There is still turbulance, just slightly less violent which in turn, reduces rear end lift. You can improve this further by placing vertical slats or fins to the rear of the belly pan.

This is not ground effect and will not produce downforce, it just reduces lift. To produce downforce the car needs to be drastically lower, have a near perfecly smooth floor and the rear diffuser needs to have a triangular side profile (look at the back of a DTM car). This moves the low pressure zone under the rear of the car which in turn pulls the car down(high pressure above the car).  

All this is well and good and can look very trick and will help straight line stability and cornering ability no end but once you've got the car sideways, it means f**k all.

Mik.



God, I wish I could learn to type faster.

Offline JFB Tech

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« Reply #10 on: July 26, 2008, 23:06:06 PM »
The Cossie rad is the same width as the standard Sierra but it is nowhere near as tall.  In the Cossie, it sits at the bottom with the intercooler mounted above it.  Overall it is about 4 inches shorter top to bottom, fabricate some bottom mounts or possibly even bolt it to the top of the chassis rails rather than underneath as normal.  This should raise the bottom of the rad by 4 inches.  A traffic cone is unlikely to bust your crossmember or sump so problem solved.
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Offline Dave

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Mounting radiators in the back.......
« Reply #11 on: July 27, 2008, 01:07:35 AM »
I have seen a couple of Sierra's with rear rads.

They had the spare wheel well cut out & it's mounted there.

Just one rad, using STD engine pump & electric rad fans.

I think the underside of the car is low pressure, so get the fan direction right, seems a common mistake. Do check this out as I can't remember if it is or not.


Also bangers run rads the same to protect them but fitted where the rear seat is.

No special pumps & STD rads. The extra water volume will increase the cooling capacity.

Any weight moved to the back is helpful.
« Last Edit: July 27, 2008, 01:39:03 AM by Dave »
Dave

Doughnutter

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Mounting radiators in the back.......
« Reply #12 on: July 27, 2008, 14:03:12 PM »
Quote from: capri v8 driver
i was just kidding  

to make thing's easyer for you, take a look at a vw siroco or audi 80 or a4 diesel radiator's. they are lower in height.

where do you have the battery? you could move that one to the boot, if you haven't done that already.

greetz paul.

capri v8 driver.



My batt is still up front, was intending on placing it behind the passenger seat as when I'm drifting i'm usually alone so I think having it there will help offset the weight of me in the drivers seat a little  

Will check the scrappys Mon to see if they have any of the suggested rads in to measure them.

Quote from: Mik
The aerodynamic diffusers work by cleaning the airflow so that it passes the car with the minimum of effort. most cars now come with basic setups on the front in the guise of an engine undertray. This reduces the amount air from under the car entering the engine bay as this increases the engine bay pressures and reduces the airflow through the rad.

Anyway, at the back the same principal applies. Place a smooth bellypan under the rear axle to the rear bumper to smooth the flow from the rear of the car. There is still turbulance, just slightly less violent which in turn, reduces rear end lift. You can improve this further by placing vertical slats or fins to the rear of the belly pan.

This is not ground effect and will not produce downforce, it just reduces lift. To produce downforce the car needs to be drastically lower, have a near perfecly smooth floor and the rear diffuser needs to have a triangular side profile (look at the back of a DTM car). This moves the low pressure zone under the rear of the car which in turn pulls the car down(high pressure above the car).  

All this is well and good and can look very trick and will help straight line stability and cornering ability no end but once you've got the car sideways, it means f**k all.

Mik.
God, I wish I could learn to type faster.

So the aerodynamic diffusers are the plastic cover things under the front of cars that are usually split / broken or have rusted bolts that are a bugger to get off when you need to remove to do a job  

I see the idea now, worth considering, especially if I could make some out of fibre glass? Plastic ones are a little beyond my fabrication skills.


Quote from: JFB Tech
The Cossie rad is the same width as the standard Sierra but it is nowhere near as tall.  In the Cossie, it sits at the bottom with the intercooler mounted above it.  Overall it is about 4 inches shorter top to bottom, fabricate some bottom mounts or possibly even bolt it to the top of the chassis rails rather than underneath as normal.  This should raise the bottom of the rad by 4 inches.  A traffic cone is unlikely to bust your crossmember or sump so problem solved.

Ah so the are not as deep as standard. Will look into this idea and price some up as a potential option  

Quote from: Dave
I have seen a couple of Sierra's with rear rads.

They had the spare wheel well cut out & it's mounted there.

Just one rad, using STD engine pump & electric rad fans.

I think the underside of the car is low pressure, so get the fan direction right, seems a common mistake. Do check this out as I can't remember if it is or not.
Also bangers run rads the same to protect them but fitted where the rear seat is.

No special pumps & STD rads. The extra water volume will increase the cooling capacity.

Any weight moved to the back is helpful.

The cars you've seen, what piping did they have?  

Thanks guys for the input, really appreciate you taking the time to reply  

Offline Dave

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Mounting radiators in the back.......
« Reply #13 on: July 27, 2008, 20:11:02 PM »
Just use pipe that won't rust of about the same size as the rad inlet/out  

It's actually very simple.

However if you copy the pic notice the tank is custom too.

Just mount it in the boot & make some ducts for air flow etc.

It's only for a track car, you would have to be insane to do it to a road car.

« Last Edit: July 27, 2008, 22:26:11 PM by Dave »
Dave

IansSaph

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Mounting radiators in the back.......
« Reply #14 on: July 28, 2008, 09:18:42 AM »
nice pic Dave, interesting rear beam set up.

Doughnutter

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Mounting radiators in the back.......
« Reply #15 on: July 28, 2008, 14:22:05 PM »
Yeah car is currently track only and although I intend to get it Road legal it will me min milage, just local shows / tracks etc

I notice you have got the fan underneath blowing up towards the body. Is this because your using the cold air going under the car to cool the rad? Any pics of the piping going throug the car pls?

And that is a nice looing rear beam setup  

IansSaph

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Mounting radiators in the back.......
« Reply #16 on: July 28, 2008, 15:03:09 PM »
i don't think its dave's he just has a huge collection of photos from the underneath of cars.... i could be wrong.

Cossy rad for you to picture, the inlets and out lets are on different sides to the 24v, however if you mounted it upside down as previouly mentioned to to tops of the legs the the pipes would be right....
« Last Edit: July 28, 2008, 15:10:35 PM by IansSaph »

Offline Dave

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Mounting radiators in the back.......
« Reply #17 on: July 29, 2008, 09:55:54 AM »

Sorry no pipe picture as it's so simple.

Just the same as up front. Just the pipe lengths are longer.

No not my car, that rear suspension was made from stratch & is one of a kind.

It is now even more trick than when that picture was took.

Dave

Doughnutter

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Mounting radiators in the back.......
« Reply #18 on: July 29, 2008, 12:49:31 PM »
Was more thinking about the route they took. Was it down the 2 inner sills or did they both run down the one side?

 

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