Thread: How to calculate radiator size?

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Hello,

Is there any way to calculate how big the radiator must be? Example, I've taken a csb 350 from a corvette and want to use it on my model a. The Corvette rad is way to big to fit into the 29 rad shell so i have to use another one.. It have to fit into the 29 shell so that size is maximum. Can i now calc the mass of the old corvette radiator and add thickness for the loss of height and width?
I will use hoodsides so all heated air have to leave beyond the engine so great cooling is needed.

Everyone i meet says you just cant calc it, You have to gamble on this one..

So, Can i calc this? And how do i do it?

/Eric

Eric, if there is a calculation, it is beyond me. I usually just leave that up to the manufacturer of the radiator and go with their recommendations.

I would strongly suggest you buy a radiator from one of the major hot rod cooling companies, like Walker, The Brassworks, PRC, or similar. They all have radiators specifically made to fit in a model a or whatever shell, and also have the inlets and outlets in the appropriate places for whatever engine you are running. It makes it so much easier and the end result is a rod that doesn't boil over in July, sitting at a red light.

We have started using PRC and love their products. The welding and workmanship are really impressive, and the price is very good. We also recently bought a Walker for my one Sons T, and it is also a nice product.

Here are a couple of pictures of my other Sons '29 shell, like you have, and this radiator was built to cool his 455 Olds for here in Florida. BTW. their website is: www.prchotrod.com/

Don

I dont want to buy a rad, I want to build one myself and for that i need to know how to calc the size. There must be someone out there that knows how to do this..

Anyway, Thanks guys!

Wouldn't the simple way be to see what's working on several similar cars and copy the size?

I'd be interested in knowing how you plan to build your own radiator?
Get a core and go from there?
Or copy the old honeycomb style radiators?

Basically on most hot ,hotrods its usually the biggest radiator you could possibly fit is usually the right size.

Denny mentioned a fan shroud. Don't hesitate to install one if you get it running hot. My friend's 57 Chevy with a mild 350 and a huge new aftermarket radiator was overheating till he got one. Also electric fans will vary in effect if they are pushing or pulling air too.

Originally Posted by shawnlee28

Basically on most hot ,hotrods its usually the biggest radiator you could possibly fit is usually the right size.

Absolutely right!

There is a disciplined engineering approach to designing air-oil (or water) heat exchangers. It is not as easy as a couple of equations however. Especially not for a car where the heat loads, air and water flow rates etc are not constant. If I was going to make my own I would probably go take a look at the specs on brass or aluminum ones out there and basically copy that.

Kitz

There are a lot of parts on a car I would build, but a radiator is not on that list.

Don

Wow Denny. If I memorize all the formulas do I get my diploma in the mail or what. As usual, Great job. I thought those brain cells were dead and yet I understood it. Scares me.

Thanks Denny,
Thermodynamics was never my strong point in engineering. This really helps as far as the automotive radiator. This is probably the best and easiest to understand presentation I've seen. You need to be a professor if you are not.

I'm on the way over to my son's place, this in hand, to look at his cooling system on his sand buggy. I think it is actually plenty adequate and I need to convince him that trying to run at 160-170 deg just isn't necessary. His stock fan doesn't even come on untill 205.

My street rod runs just fine at 190-200 regarless of outside temp. Mostly by accident but after reading your article I see why now. I'm going to try and measure some temps at various points to better understand what is happening.

On the Dodge diesel trucks we have a cooling issue with the injector pump that some guys have tried to understand and this lecture will certainly spread some light on this.

Again thanks for the great lesson.

Denny, do you have the formula for Nuclear Fusion, specifically related to splitting the atom handy? How BIG is that computer of yours??

Don