size of radiator

[JJW]

Hi I'm jongwook from south Korea.
How can I determine the size of radiator?

[JJW]

Hi I'm jongwook from south Korea.
How can I determine the size of radiator?

[Wesley]

Well, using a tape measure or vernier caliper, measure the radiator dimensions! Poof, radiator size determined.

Ok, maybe that's not what you mean. But there is a very effective search button.

[Luis_85]

Jajajaja Wesley i don't that was the answer he expected xD.

@JJW: As Wesley said mi first option for you will be to look the previous post of this subject. I did the design of the radiator size for our 2008 car and i founded the forums really helpful.

[Austin B]

Also keep in mind that the use of a (ducted) fan can reduce the size of the radiator needed. I'm sure thats covered in the other topics though. Just my 2 cents.

[barba_p]

Also not bad idea is to draw radiator in CATIA.
That way beside acctual dimensions you can determine momentum of inertia

[Pero]

Thanks to barba_p once again great ideas.
For radiator core you should have cca 300x300 mm with cca 20 mm thick core, for 100hp.
Fan is a muss on fsae, so either put it very close to radiator, or use tunel from radiator to fan, in that case try to put it further away from radiator. And also tunel should be wery good sealed, so it pulls air only through radiator.
In case you dont have enough cooling, its better idea to use bigger fan with more flow than increasing flow in water pump.

[AlexS]

theres a thread somewhere which discusses cooling design pretty extensively, i think it was started in 03 sometime or maybe 04, and the last time it was active was end of last year i think.

lost of discussion, not a heap of conclusions. best idea would be to go to vehicle design, vehicle aerodynamics, and obviously ic engine cooling texts to get a bunch of analysis and optimisation methods/techniques. compare them and pick your fav...

worth mentioning also is that a radiator about 300x300x20 does tend to be sufficient for an sae car application, althought all the data sheets i have come across seem to show that that size generally removes only bout 20kW at about 6m/s and 100 l/m ...

youse have similar numbers?

[Pero]

That would be the numbers. Its wery hard to get correct numbers that could be applied on car, even when building real car, calculations give only orientation numbers, and actual size is determined in testing.
Fan is most important when idle, but then engine produces only about 7kw.

[Mike Hart]

The long answer is, read through the massive heat exchanger thread. The short answer is, it's hard.

Even the manufacturers of bikes (I work for one) struggle to find the definitive answer to radiator size and most is obtained through that wonderful thing called testing. I designed the cooling system for last years FSAE car and it was a pretty involved thing to do (it took me about 9 months of research and testing). It worked in the end (kept the car cool at Germany when being ragged in 29deg C heat), but wasn't perfect and needed tweaking over the 300km of testing we did.

Best bet is to start with the same size (ie, height, width, depth and fin density) as the standard bike. Either modify or replace the mechanical water pump with something that has a higher flow rate and fit the biggest fan you can find with some proper ducting around it and the rad. If it cools it too much you're half way there since you can reduce the size of the fan or lower the pump flow rate.

Many people will argue with me about this, but I say, leave the thermostat in. Taking it out presents the flow with zero restriction and lowers your block pressure from standard which isn't great since the water will just wang through without picking up the heat. You can play around with restrictor plates if you don't like the stat, but you'll get more reliability quicker leaving it in.

Hope that helps!

[Mikey Antonakakis]

This might be a deft question, but is the issue here in making the radiator too small? Or too large? Why shoot for an "optimum" size, just for weight savings?

[Chapo]

I think one of the major issues with the radiator is the weight, and also the weight balance/positioning. If you think about it your radiator has the empty weight of the heat exchanger its self and also all the water it contains. To make matters worse it has to be in the airflow (well pretty much in the airflow) to work properly. This makes it stick a fair way out from your center of gravity and contribute greatly to your moment of inertia for turning. You could put it up high above the engine and then you increase your CoG.

And on the other end of the scale if you make your radiator to small say good by to your engine, though ours managed to live after hitting almost 160 degrees celsius.

On a different note has anyone tried anything interesting with rad positioning? like under the driver or anything, it would provide really interesting packaging considerations to get the airflow right. I could be wrong here, but i believe one of the 1970's honda F1 cars had the engine at the rear and the radiator at the front, and all of the tubing connecting the two acted as a heat exchanger down the side of the car. Pretty nifty.