Fan Size?

[PoorCollegeKidd]

I'm gathering parts for my RB20 swap in a '92 240 HB. I am trying to save money whereever I can. I was wondering what electric fan option would prolly be the cheapest and still work. I'm up here in the north arctic circle in Washington. So, I've seen 12" to 16" and am wondering what I really need. Anybody have a CFM estimate? Thanx a lot!

[Joe]

2500cfm minimum IMO.

[ca18detizzle]

same question. same state. you on NWN?

[240sxed]

Heh can we can some imput on thermostat activated switches, and how exactly?

or manual/no switch

[Slo_240sx]

Thermostat activated? The only thing close would to have a Thermistor that would act as a ground once it closed. I'm gonna run a relay, and you can go buy those fan control units from autozone that has a knob and will tell the fan weh nto turn on based on how much you turn the knob. Basically its just a variable resistor. There is a temperature prob that comes off of it that slides inside your radiator hose for the reading to the control unit. I think this is how most guys have it setup unless they are running straight on key-on ignition power.-Alex

[Wulfgang]

Don't skimp on fans. Search this forum and you'll find that overheating is one of the most common problems after a swap. Give your cooling system some thought, even though you are in WA.

And, no you can't use just a thermistor. Can't handle that kind of current, and if it could, it would just keep getting hotter from the current flowing through it. No, you have to use something a tad more sophisticated.

There are lots of little temperature switches you can buy that just turn on when the temperature reaches say 90ºC and turn back off at 80ºC. In fact, your 240 and RB20 both have a switch that does just that. You could use it, or you could buy one. Then the switch hooks up to your fan relay so that no fan current goes through the switch.

There is also a nice microprocessor controlled fan speed controller from PermaCool. It reads your coolant temp and adjusts your fan speed from 60 to 100% based on temperatures you specify. I'm working on something similar that goes from 0% at 80ºC to 100% at 90ºC, but I've still got a few bugs to work out. These connect directly to the fan motor since you can't do variable speed control through a relay. They are the best solution IMHO since they avoid shocking your alternator regulator with 20 amp bursts of load.

[Sil240]

Definetly get a good radiator and fan because my friends 25 overheats all the time.He just used the stock KA radiator, but now he's going for a Koyo i believe

[blues14]

I have a 12'' pusher fan on my s14 rb20det with stock ka radiator. works great with no overheating problems............yet:)

[ca18detizzle]

ok, just picked up two 10 inch fans. works great. well my RB20DET in my s13 never overheated without one on a 80 degree + weather. But now it just stays cool! works really well! btw, it's the ones from autozone. took 30minutes to install and it works good IMO. It stays at the temperature i want it steady.

[Slo_240sx]

Don't skimp on fans. Search this forum and you'll find that overheating is one of the most common problems after a swap. Give your cooling system some thought, even though you are in WA.

And, no you can't use just a thermistor. Can't handle that kind of current, and if it could, it would just keep getting hotter from the current flowing through it. No, you have to use something a tad more sophisticated.

There are lots of little temperature switches you can buy that just turn on when the temperature reaches say 90ºC and turn back off at 80ºC. In fact, your 240 and RB20 both have a switch that does just that. You could use it, or you could buy one. Then the switch hooks up to your fan relay so that no fan current goes through the switch.

There is also a nice microprocessor controlled fan speed controller from PermaCool. It reads your coolant temp and adjusts your fan speed from 60 to 100% based on temperatures you specify. I'm working on something similar that goes from 0% at 80ºC to 100% at 90ºC, but I've still got a few bugs to work out. These connect directly to the fan motor since you can't do variable speed control through a relay. They are the best solution IMHO since they avoid shocking your alternator regulator with 20 amp bursts of load.

Thermistor is not to be used on the high current side it is to be used on the control side of the relay. Sorry you misunderstood but the thermistor would be the ground to close the relay depending on temperature which in turn would close the controlled side for the high amps. Myself out of everyone, knows better than to pull some hacked chit like that.-Alex

[PoorCollegeKidd]

Thanx or all your input. I am wondering what prices I am dealing with for all these solutions. I have to spend under 100 bucks and lower if possible.

[NISMO_RB25]

A decent fan (just one) is going to run you 50-100 and that isn't really ideal. 200 will get you the flex-a-lite dual 12" fans. I would recommend that setup.