Radiator volume or fan cfm? Which to prioritize?
Posted by kabobkebabkabob@reddit | projectcar | View on Reddit | 24 comments
My 1uz swap currently has a dual core radiator that's a bit small for this engine, with a total of 2800cfm with the spal e-fans.
Occasionally it gets a bit on the hotter side (215F), typically at slower speeds, crawling, going up passes etc. The fans are set to regulate temps from about 205F so the fact that it starts to exceed their capability is concerning.
I'm maxed out on clearance so I can't go thicker with either thing. But I could potentially go back to a single core radiator which would open up room to I think fit a big ass 4000cfm Volvo fan.
With my issues mostly being at slower speeds, do you think it's worth the volume sacrifice to go for a bigger fan? On the highway I sit pretty comfy in the 190s F.
Cheers
Local_Bobcat_2000@reddit
If it overheats not moving or moving slow, you have a fan problem. If it overheats when moving fast you have a radiator problem.
DirtCheap1972@reddit
You need a bigger radiator
kabobkebabkabob@reddit (OP)
Haha well shoot. This is as big as will fit.
TurboDorito@reddit
Is it properly ducted from the front and at the back? No point having bigger rad or fans if the air isn't going where it needs to.
Proper ducting will likely reduce temps better than anything else.
kabobkebabkabob@reddit (OP)
Yes though I'm going to open up my hood vents more though to increase the flow. Right now you can see they are a bit on the safe side to minimize water entry but I'm just gonna yolo them open.
Plus after looking at it the 200th time I'm seeing a spot I could jam two more 5.2" 313cfm pushers in front of the condenser beneath the grill. It'll be janky but I think I'ma give it a stab.
DirtCheap1972@reddit
Gotta cut more. Blowing more air at a smaller cooling system isn’t gonna cure this issue. You need a rad with a bigger capacity than the engine so you don’t cycle hot water back in before the thermostat closes
kabobkebabkabob@reddit (OP)
Do you have any tips for hunting down a radiator with specs similar to this one? I tried chatgpt a good bit but wasn't getting anywhere.
DirtCheap1972@reddit
The fan in my Datsun I ran as a pusher so I had more clearance between the rad and engine (for a thicker rad)
DirtCheap1972@reddit
For my Datsun truck I ordered custom through norther radiator. They custom build the radiator to your exact specs
kabobkebabkabob@reddit (OP)
Ok super interesting revelation. I actually supposedly have more capacity than the factory ls400 radiator. Even factoring in a 3 core volume discrepancy vs 1, seems like I actually have more.
So maybe it does just come down to a fan issue. At 2800cfm unshrouded (but covering most of the radiator) I'm probably well under what's needed.
I did try a very shallow shroud and it yielded clearance issues.
fmeupfam14@reddit
Can you fit an aux radiator somewhere?
87eebboo1@reddit
The only limit is your imagination!
kabobkebabkabob@reddit (OP)
And the dimensions of this engine bay 😂 my last real resort seems to be to delete AC and even that would be reducing surface area for a third core.
Special_EDy@reddit
Can't you install a bigger fan on the front of the radiator, behind the grill?
There is nothing wrong with a pusher fan, most aftermarket fans can be set up in either a push or pull configuration.
jimbofranks@reddit
I realize you can’t go thicker but could you go wider or taller? I’d rather have more radiator capacity myself.
When it goes to 215 do the fans cool it down below that? Or is that as low as it will go? It’s possible that the thermostat isn’t working properly and not opening until too late.
kabobkebabkabob@reddit (OP)
I could maybe go 2" wider if the radiator was a tad shorter. Problem is I've committed to this hood pin placement and removing any more radiator support could be a structural liability. But maybe! I'd only gain more volume though as the added surface area would not be getting airflow.
Also the trick is finding the exact radiator dimensions I need.
jimbofranks@reddit
Sounds like you’re close to the limit right now.
I had an MGB years ago that would overheat in summer traffic. My tactic was to turn on the heater. I like your idea of adding an oil cooler or a heater core. It beats sitting in traffic with the heater on!
juwyro@reddit
Oil coolers might help you out some too.
kabobkebabkabob@reddit (OP)
I think that's probably the best bet
juwyro@reddit
I'd look into better fans too.
kabobkebabkabob@reddit (OP)
I wish I could fit better. This was the highest output set of fans I could find that would fit.
juwyro@reddit
Is there more room for pusher fans? Is the radiator shrouded?
Dude_Love_1974@reddit
If you can't go thicker, get the tallest/widest radiator you can fit in there.
How is the water pump? Has the impeller deteriorated?
I would also check to see what thermostat you have. Aftermarket thermostats suck so verify if it has an oem thermostat or an Aisin which is the OEM manufacturer.
amg-rx7@reddit
What are you running for a thermostat? If stock, look for a 180* thermostat. That should help