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Radiator for 500+hp

Captain Bondo

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Sep 18, 2002
What is everyone doing for radiators?

Lately it seems my radiator is not up to snuff. It could be ducted a little better so I will try that and some water wetter, also I am using a V70 fan but only using the low speed setting, so I will try the high instead (IPD HD Nissens 3 row rad).

But aside from that, under fairly sustained, but relatively low speed, hoonery my temps climb pretty hard. I think the slightly more responsive turbo means I ran rip in and out of boost quickly at low speeds. Freeway pulls, or even a quarter mile run, would be fine. But doing tuning where I do pull after pull through 2nd gear starts to cook it.

Has anyone used and "GM style" rads? The inlet/outlet are in the right spot....
 
Just buy one that's about the right size and tig to fit. :e-shrug:

For $40 out of the junkyard, my 92+ n/a 940 Nissens recent replacement is working fine.
 
I think the best solution is finding a wider radiator if you have the room. Often that means redoing the IC, eliminating a battery, etc. But the increased surface area will be better than a fatter radiator.

Also, I believe the fan you're using in insufficient. I used an 850 fan for a while and discovered it was a 15 inch bottleneck and it did not even perform as well as the clutch fan setup it replaced. So I upgraded to a 17.5 inch Ford T-Bird SC fan, which I mounted in a 740T shroud. Now I have plenty of fan and still using a stock sized 3-core radiator in my 242. But if I outgrow this, that's when I'll be installing a wider radiator.

My T-Bird fan install can be found here:
http://www.davebarton.com/ElectricCoolingFans.html
Dave B

coolingfan-sc-6.jpg
 
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Be sure you have everything working for you before you go get a bigger radiator. You can spend a lot of money and effort to have the exact same weak link in your cooling. Im on a stock nissans 240 radiator and I can beat on it hard for 10 minutes straight and temps are stable with 400whp. I also have a small evo intercooler, all the stock ducting, splash pan, and nice fan shroud setup.
 
Thanks guys.

I agree I need to clean it all up first, as I mentioned there's some room for improvement with the existing stuff. I was just interested to get some more datapoints. That said I think it's possible somewhere around 450whp is the tipping point, as I didn't have any issues around 400whp either. I hope to see 550 or 600 in the near future so I'm also thinking I should plan ahead a little. Another thought is I also have no idea if the whiteblock may need more or less cooling for a given output... my guess is more in some ways at least since the open deck means enforcing strict limits on coolant temps is more critical.


Dave - I would think that if I didn't have enough fan, I would see issues at idle and very low speeds though, yeah? Even on a hot day idling in traffic it's cool as a cucumber.

When i say low speeds I mean 30-50mph, fast enough i think the rad airflow due to the vehicle moving should be the main source of flow. This also suggests to me that improving the ducting to the rad would likely help. I should at least try the high speed first i think since it's just swapping a wire.

A wider rad would make sense but my intercooler is a 24x12x3" core and the inlet/outlet restrict how wide I can go, so I'll likely have to change that as well. My intercooler only blocks the bottom 1/3rd of my rad or so though, so that should help too.

I'd like to redo everything with some manner of v-mount in the winter and something maybe more like 28" wide.
 
I'm running a early 90's ford aerostar core with tanks I welded on. Car stays cool even when 2nd/3rd gear is used heavily threw the corners. Cools the motor quickly from 210 to 190 at idle with a 16 inch fan. I can get core dim if you would like. But its just as big as an npr intercooler.
 
Dave - I would think that if I didn't have enough fan, I would see issues at idle and very low speeds though, yeah? Even on a hot day idling in traffic it's cool as a cucumber.

When i say low speeds I mean 30-50mph, fast enough i think the rad airflow due to the vehicle moving should be the main source of flow. This also suggests to me that improving the ducting to the rad would likely help. I should at least try the high speed first i think since it's just swapping a wire.

Your radiator needs very little air-flow at idle and light cruise, so an undersized fan will not create temp issues there. An undersized radiator will though.

Are you seriously running it on low speed only? Definitely hook up a high speed circuit. I have a diagram HERE (pdf... see page 4) I did on my daughter's 240 to use the high speed circuit triggered by the sensor in the radiator if temps climbed or also with a manual override switch.
 
I'm running a early 90's ford aerostar core with tanks I welded on. Car stays cool even when 2nd/3rd gear is used heavily threw the corners. Cools the motor quickly from 210 to 190 at idle with a 16 inch fan. I can get core dim if you would like. But its just as big as an npr intercooler.

That's the odd thing- everything cools down FAST as soon as I stop beating it, the problem is the temp just climbs steadily while I do beat it, like the motor just makes heat faster than the rad can take it away. I don't really want it to hit 200+ degrees when driving it hard.

The more I describe this the more it points to ducting though. lol. I will fix it tonight.


I'll change the speed too- I am using the OEM 2 speed relay so I can just open up the connector, and put the wire from my VEMS onto the speed 2 pin on the relay instead. Right now the overtemp switch kicks the high speed on, but that switch doesn't close until 200 degrees, kinda too late.

Dyno tomorrow so I am trying to cover all my bases. haha.
 
My 9 series is ducted, although the npr is in front of it. But I stay cool in the 190 range while driving it, and playing with it. So a loaded motor in the 40/50mph range stays spot on.

Do you have an airdamn, or something to create the negative pressure and draw air through the radiator?
 
had a chevy do the same thing ended up being a headgasket leak slightly into cooling passage. does it use any coolant ?
 
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