Upgrading radiator

Patrick · #1 7th February 2008, 18:23

I'm thinking of swapping my radiator out for some more efficient as I'm not of the opinion the BMW M10 rad is up to the job (especially given the capacity increase of the engine).

Any ideas on what other options are suitable?

I found this site http://www.radtec.co.uk/ - nice but muchos expensive.

MartinClan · #2 7th February 2008, 19:44

Hi Patrick

Are you sure that you will have a problem? You have an oil cooler as well don't you?

I am not sure what rad you have. I used the rad from an early 325 and it's pretty chunky. I mounted it as far up as I could so that the crossmember didn't obscure it too much. Of course I don't know yet if it will do the job.

You might find that you get a better improvement just by getting Marlin to put louvres in the bonnet sides. I guess that would must make quite a difference to the airflow.

If you have to change I think the best solution would probably be Marlin's custom crossflow rad but if it were me I think I would wait to see if I have a problem first.

Best,

Robin

Patrick · #3 7th February 2008, 19:53

I've had it start to overheat standing on idle in traffic. Temp drops down again when I start moving. Maybe I just need a bigger fan / more vent holes.

RobDorey · #4 8th February 2008, 07:33

I've had mine running in the garage and the gauge hit a little over 100°C before the fan cut in. The fan didn't stop and temp stayed up around 100°C. A little worrying. I took it up the road for a spin for a maiden flight (Awesome by the way. Even though it was running on 5 (no.6 ign coil blew taking part of the ECU with it. More on another thread.)) and the temp does go down a bit but I'd like to see 90°C tops before I'm happy. I've use rubber strips to seal the sides and top, which will direct the flow through the rad and not around it and also put in an 88°C stat to replace the 92°C. Of cause, it could be that gauge is not to be trusted. I'll let you know how that works out when I get the ECU back from the repairers. (M50 2.5 with M10 rad)

Patrick · #5 8th February 2008, 07:43

Mine normally sits around 80°C, standing on the drive it goes up to 90°C where the fan kicks in and it stays there. However out on the road under a bit of stress it'll go up to 100°C until I start moving again.

RobDorey · #6 8th February 2008, 07:54

I think that the heat dissipation capacity for the M10 rad is border line with the M50 motor.
The rad is everything on the M50 because it doesn't have an oil cooler like the M20.
I see that there are un-drilled take-offs on the oil filter housing which are used on the M3 Motors, so I could use an oil cooler if the motor temp remains high.

Patrick · #7 8th February 2008, 07:58

I've at least one spare oil filter assembly / housing from an M52 if you want something to experiment with?

RobDorey · #8 8th February 2008, 08:05

That would be great.
I have a good friend locally who owns an engineering shop who has made lots of stuff for my car. I'm sure he could do something with it.
Looking that your build, an oil cooler fits nicely just behind the grille.
How much do you want for the housing?

Patrick · #9 8th February 2008, 08:13

it's just knocking about the garage you can have it for the postage cost

RobDorey · #10 8th February 2008, 08:17

Thank you, Sir.
Soon as it arrives I'll get my man on to it.

Patrick · #11 10th February 2008, 14:47

I've dug it out this weekend and put in a box, can you email me your address please?

RobDorey · #12 13th February 2008, 12:15

Just a small thought.
Does it make any difference to the cooling if the flow goes from top to bottom?
If so, I may well have to re-plumb the car.
I've got hot coolant in at the top and out of the bottom.
Any thoughts?

MartinClan · #13 13th February 2008, 12:38

I am sure that any radiator works better one way than the other but considering that the water is pumped around at a fair rate I suppose it only makes a very small difference.

I guess that the main thing that affects the ability of a cooling system to cool is the rate at which the heat can be transfered from the water to the air. This is in turn affected by:

A. The surface area that the heat exchanger (radiator) can expose to the air.
B. The amount of air that is flowing.
C. The temperature of the air.

A. Is satisfied by having a bigger rad, or one that has more cores (tubes)
B. How fast the air is flowing - determined by the fan when not moving
C. Determined mainly by how fast the air can escape after it has been forced through the rad. I think this is one of the problems on the Sportster as the engine fills most of the engine bay.

If your car isn't painted yet then louvers in the bonnet top, followed by the sides would help. Otherwise - there's no substitute for size as they say. Fit a rad with more surface area...

All IMHO of course :-)

Robin

peterux · #14 18th February 2008, 21:19

Quote:

Originally Posted by Patrick

I've had it start to overheat standing on idle in traffic. Temp drops down again when I start moving. Maybe I just need a bigger fan / more vent holes.

Whilst testing my dashboard on Sunday, I left the engine running whilst I took some photo's.
The rad fan had switched on and was running fine.

Then suddenly, the coolant started to boil and was being ejected out the top of the radiator!
I have what I think is the M10 radiator with the BMW screw on radiator cap. I was able to tighten the cap about a quarter turn, so maybe it just wasn't tight enough? (Do you tighten this type of cap right down??)
But, like the rest of you, i'm starting to wonder if my radiator and fan are not up to the job. I bought a rad fan to fit on the front, so it's only about 9 or 10" daimeter.
I have vents in my side bonnets but none in the top bonnets.

It was only about 8 degrees ambient, so hardly a hot day! I only have the 2.0 litre engine. I'm also wondering if the water pump might be knackered?

I am thinking I might need a much bigger fan on the back of the rad?

Any ideas or suggestions of a bigger fan?

Peter

RobDorey · #15 19th February 2008, 08:46

One thing I discovered is that the cap that screws on the M10 rad has a pressure relief valve which I've modded so that the cap is just a blanking cap.
I've used an expansion tank from a Volvo which has a PRV already.
So I took the guts out from the cap, with the careful aid of a small wood chisel, made the inside of the cap flat with a little Araldite and used a rubber disc for a seal. The overflow pipe is then routed back to the expansion tank.

GreatOldOne · #16 19th February 2008, 11:15

Quote:

Originally Posted by MartinClan

If you have to change I think the best solution would probably be Marlin's custom crossflow rad but if it were me I think I would wait to see if I have a problem first.

Is that the radiator that is listed on the module price lists? If so, that's what we already have, isn't it? I go my Rad from Mperman:

http://www.madabout-kitcars.com/foru...light=radiator

And IIRC, this is what Pete & Patrick have as well... Do Marlin sell an uprated radiator?

Patrick · #17 19th February 2008, 11:24

Quote:

Originally Posted by GreatOldOne

Is that the radiator that is listed on the module price lists? If so, that's what we already have, isn't it? I go my Rad from Mperman:

http://www.madabout-kitcars.com/foru...light=radiator

And IIRC, this is what Pete & Patrick have as well... Do Marlin sell an uprated radiator?

Yes they have a "crossflow" one but I don't know what car the originates out of. The mount is different the BMW M10 one.

GreatOldOne · #18 19th February 2008, 11:40

Ok - so I'll bite... Looking at the pictures on Simon's site (he has a marlin x-flow), why is this a more efficient radiator?

To my untrained eye, it looks verry similar to the rad I have, albiet turned through 90 degrees and minus the filler cap (the main water galleries are on each side rather than top and bottom).

OK, It looks slighter thicker, so more copper / piping = greater heat dissipation... But does sending water left to right make it more efficient than top to bottom?

Patrick · #19 19th February 2008, 11:54

I have observed that all newer cars (I've looked at) have cross flow radiators. Google says "cross flow more efficient" but I don't see any explanation as to why, only that they are.

GreatOldOne · #20 19th February 2008, 13:31

Hmmm - these people say it's more efficient:

http://www.chevyhiperformance.com/te...nfo/index.html

Quote:

Crossflow radiators have radiator rows located horizontally so that water travels across the radiator, and downflow radiators have rows positioned vertically so that water travels downward. A crossflow radiator is typically more efficient than a downflow for the simple reason that the pressure cap is located on the low-pressure side (opposite the outlet or upper hose location). This cap location allows sustained high-rpm operation without forcing fluid past the cap. In addition, under-hood-space considerations typically allow a shorter and wider crossflow radiator to utilize a larger core with added surface area, which provides more effective and efficient cooling.

Yet these people start off sitting on the fence, yet then say it'll cool better:

http://www.wizardcooling.com/faq.htm

Quote:

No, not necessarily. The important factor is the amount of heat dissipation surface the core has. The coolant flow direction is not important. Many aluminum radiator manufactures make "cross flow conversions" for many original down flow radiators. Although these radiators will cool better than the original, they do not look, mount, or fit like the original These cross flow conversion can require anything from new hoses to major sheet metal modifications. Cross flow conversions are the easiest and cheapest to design and manufacture. An installer must consider the cost of additional modifications that are needed when considering a cross flow conversion. Although Wizard Cooling is fully capable of producing cross flow radiator our primary focus is to design a build a radiator that will be configured like your original, fit the original radiator mounts, and cool what ever horsepower you have.

It's all very confusing!

I think I'll forget worrying about it until I actually have the damn thing running.