How do you know if you have "enough" radiator?

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MRGTX

MRGTX

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Is there any rule of thumb on the radiator size to horsepower ratio?
I'm not sure if my radiator will be enough for my impeding motor swap and I'd appreciate any feedback.

Back in the 1990s I bought an "upgrade" radiator for my 318 Dart with the anticipation of swapping in a 340 or a 360 when I finally had the money. This was supposed to be a stock replacement for a 340 car so I assumed it would be enough. I didn't have a lot of money back then (nor do I now) so it's a basic radiator (not aluminum) with metal end tanks at least. It's significantly bigger than the laughably small stock 318 (non A/C) one...but it still looks like a non-high performance car unit.

Assuming it is indeed a stock equivelant to a 340 car, should it be adequate for a tuned motor?

I drained and pulled it last night, bringing it in to be boiled/tested...I plan to run electric fans. I know a good radiator can be relatively affordable but I'm on a shoestring budget...so every penny counts.

Thanks for any thoughts!
 
I would think that if you are doing a mild 340/360, and you are adding electric fans... you would be fine.
Did you have a shroud?
How were temps before?
 
Get a junkyard shroud and solid used mopar clutch fan rather than messing with electric fans. Thermostatic clutch fans cool great.

Unless you already have electric fans.
 
Thanks, guys!!

Lonewolf3165 said:
Need to know more about the engine your putting in it.
Click to expand...

I'm looking at a 1973 LA 360 4bbl tomorrow...otherwise, I'll almost definitely end up with a 5.9 Magnum.

I'd like to run a decent cam, eventually go to some high performance heads, etc...but I expect to keep it relatively mild...~350hp. I'd like to take it to the drag strip a few times a year but I don't forsee any roadcourse work. :)

sazzlefrats said:
I would think that if you are doing a mild 340/360, and you are adding electric fans... you would be fine.
Did you have a shroud?
How were temps before?
Click to expand...

Temps were fine on the stock 318...no signs of overheating ever....but I have no fan shroud, sadly. It was gone before I got the car..why do people remove those things?! Not sure if a stock 340 shroud would fit but I suspect it would be a tricky part to find....which is why I'm thinking electric fans.

Rice Nuker said:
Get a junkyard shroud and solid used mopar clutch fan rather than messing with electric fans. Thermostatic clutch fans cool great.

Unless you already have electric fans.
Click to expand...

If I can find a shroud that fits...this is probably a great way to go...


So you guys susepect that it should be ok? Do you guys run Redline Water Wetter?
 
The answer IS:

The way you know if a radiator is enough for a engine.....is measure the coolant that comes out of a FULL cooling system (block/heater core)....then you need 2x the capacity of the block/heater core in the actual radiator CORES/TANKS.

Ideally you need an assembled system to measure this out like I described.

But the general rule is.....a 2 core radiator will cool a SB upto 400hp....and a 3 core will cool a SB or BB over 450hp.

I dont recommend running a Side to Side Flow 1 core radiator.
Instead, I recommend a top-bottom, 2 or 3 core for high performance applications. Champion Radiators have a good review, and dont cost a arm and leg......I have a 3 core and if I remember correctly I paid $235 shipped for it with (2) electric fans included....it fit like a glove...and works ok....no complaints here.

Heat soak and thermal radiance, will heat soak a Single core too much to really pull the heat from it effectively for a street car...unless its pretty big. (surface area)

Bottom Line IS: if your 340 replacement radiator is okay....you should be fine.
 
rad thickness more important than number of cores... min. 2"
clutch fans typically turn at about 80% of crank speed and you may over heat in traffic where airflow is low.
lots to consider here...pulley size,water pump speed,thermostat, fan size,pitch and shroud all factors as well as clean block heads and rad,engine compression etc..
think cooling system....
 
Size of the cores are very important..... you can have a 2 core radiator cool better than a 3 core if the cores are wider in the 2 core.....in other words, a two core radiator with 1" cores will cool better than a 3 core radiator with 1/2 cores....
 
MRGTX said:
Thanks, guys!!



I'm looking at a 1973 LA 360 4bbl tomorrow...otherwise, I'll almost definitely end up with a 5.9 Magnum.

I'd like to run a decent cam, eventually go to some high performance heads, etc...but I expect to keep it relatively mild...~350hp. I'd like to take it to the drag strip a few times a year but I don't forsee any roadcourse work. :)



Temps were fine on the stock 318...no signs of overheating ever....but I have no fan shroud, sadly. It was gone before I got the car..why do people remove those things?! Not sure if a stock 340 shroud would fit but I suspect it would be a tricky part to find....which is why I'm thinking electric fans.



If I can find a shroud that fits...this is probably a great way to go...


So you guys susepect that it should be ok? Do you guys run Redline Water Wetter?
Click to expand...

I have a 26" fan shroud that was removed from an original 74 Dart 360 car. Check out my add in the classified section. BTW, I'll be out of town for a week so if your interested I won't be able to get back to you until I return.
 
I bought a 2 core 1" wide cores aluminum for 125 online for my 360 no shroud the cheapo blue flex fan and it stays plenty cool actually had to put in a high temp thermostat to make heater and defrost work better lol now it stays right around 150-160 even in stop and go traffic it was at 100-120 with old thermostat
 
"2 core 1" wide cores aluminum"..


Yes, that is what I have also and actually runs a shade too cool
 
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