Last week I tried to convert from a single fan to dual LS1 fans in my 92 RS 305 TBI and my car still ran hot.

I have 180 thermostat with lower temp fan switch, new coolant in system, new hoses, new radiator cap.

First (primary) fan is wired to stock harness, second fan is wired to a relay and circuit breaker with fan switch in the head that'll ground out to turn second fan on.

Both fans running at the same time bogged down my electrical system.
Fans would cool car off fine during idle, but while driving it seem to run hot,
I know that the temp gauges on these cars seem to not read accurately but with both fans running it would not cool down correctly.
For now I've converted back to stock single fan.

What could I have done wrong? I've researched dual fan conversions for a while now should I go dual fans from Spal or Derale?
Should I try to get a bigger aftermarket single fan that has more CFM's?
I live in Texas where we see 100+ temps daily with humidity and I do not want to worry about overheating in traffic.

 

I guess first of all, what do you mean by "hot"?

 

And how fast are you driving when it heats up?

 

Is your alternator supplying enough juice for the fans? Lower airdam installed?

 

Lower airdam is intact and works correctly.
Alternator is stock Ac Delco just got a new one two months ago.

 

Hot meaning it will get to a point where it cannot cool down anymore after driving for a bit. With dual fans i expect it to cool itself down if i am in stop and go traffic.
I know the air dam helps while driving on the highway but when I get to stop and go traffic with both fans running it will not cool.

 

Lower airdam is intact and works correctly.
Alternator is stock Ac Delco just got a new one two months ago.

 

Yeah, but the temperature is important for the troubleshooting discussion. If it's like 200°, that's not "hot" for these cars.

In your ECM calibration, the primary fan is probably set to come on at something like 220 anyway and the temp switch in the head probably hotter than that.

Also just because you have a 180F thermostat doesn't necessarily mean the engine will always cool to that temp, especially in severe heat. My car with a 180F will get up to 195-200 with the A/C on hot weather. But, that's not running "hot".

 

What I'm saying is your stock alternator might not be capable of handling the additional power draw of two more powerful fans. I'd start by comparing the amps output of yours to an ls1 unit. Ideally you'd know the difference in power draw between the two fan setups and whether your system can support the increased load.

 

Not familiar with these fans, but make sure they are wired correctly and not trying to blow air forward through the radiator. Should be wired to pull air through radiator and push across engine.

 

Pics of your install would be good.
Do you have the fans against the radiator? if I recall, the TBI sinngle fan uses a switch in the passenger head to activate. Where is the switch installed for the second fan?


"still ran hot"
You might have other issues...maybe a clogged radiator or something... or the sensor for the gauge could be bad. ... if its running hot with a single fan, the LS1 fans, or most other fans, won't really help. If anything the LS1 fan will just help it cool faster if the system is operating correctly. Maybe a Taurus fan would overcome ay issues you have, but it'll suck way more juice.....


These fans suck a ton of power.... For me, the LS1 fans sucked juice at idle in Drive.... to the point where the battery would die if idling for a longish time.....I switched the motors to TPI fan motors which are the same as the stock single fan motor......... they are a direct swap and look the same but draw less amps. I felt no change in the amount of air drawn by the TPI and LS1 fan motors hoestly.. .but the TPI doesnt drain the battery.....

 

The temp will remain constant at under 220 / halfway in my Firebird.....it may go to 190 / vary from there depending on driving conditions. but basically stays in that range..... it worked this way with the single fan as well. Theyls fans just cool a bit faster than the single fan................ I''m not sure where the gauge stays on a camaro though.....But the fan shuts off at a given temp and the engine maintains a temp before the fan comes on again, then shuts off once the fan switch lowers temps to a certain temp. As long as you're not overheating you should be ok... again, the Ls1 fans will just lower temps to a certain temp set from the factory,,,,, since your fans are wired separately, and on different sensors.... i willing to bet at times only one is running while the other shuts off...one Ls1 fan doesnt cool that well though. I have mine come on / off at the same time.

It COULD be they are operating just fine.

if its actually staying too warm and / or overheating though, id look at the clogged radiator theory or maybe a weak pump. or something like a faulty thermostat.

 

This is why I'm glad I have a laptop and a cable to read the PCM data. When the needle shows what looks like 210° plus on my GTA, its really only at 200°.

I have a pretty heavily modded Lt1, and it makes plenty of power. I only have a single TPI fan on the car right now because the 2nd died, and the single primary fan is capable of cooling the car down in a normal PCM fan cycle, trips at 195°, hysteresis takes it down below 195°, fan shuts off, rinse and repeat. The only time the fan doesn't shut off is when I'm in stop n' go traffic stuck below 30mph or so. Then there is just not enough natural airflow over the radiator from the air-dam, but even then it really never goes about 205° (which reads more like 220° on the stock gauge)

I will eventually put a dual setup from an LT1 or LS1 on it, but not this year.

 

you’re correct. wiring for the second fan is separate and it did draw a lot of amperage.
it might be beneficial for me to swap out both motors that draw less amperage.
im thinking of buying a bigger radiator and dual fans with a shroud and see what it does.
when I say it’s running hot the meter will go all the way to red, it usually takes a while to get there though. I feel like when I am highway driving then hit stop and go traffic in really really hot weather it’ll creep up pass 240 mark. But I’m sure that my temp gauge is not accurate.
car will boil over if the temp gauge reads way pass the orange 260 mark.

 

primary fan is controlled by ac switch and can switch in the block which I changed to a low temp switch that activates around 205*.

when I say running hot I mean it gets to the point where it cannot cool down.
running around 200-240 range is normal in my car but my gauge will start to continue to creep up and will not go back down.
it is not overheating because I am not getting a boil over.
I just feel like with two fans it should run cooler. It’s possible my temp gauge is faulty, I’ll look more into it this weekend.

 

It sounds like you might have some other issues... maybe the fans are just helping the car stay cool eough to slow down the overheating....maybe change the thermostat, and flush the block / reverse flush or change the radiator. Maybe even get a new water pump if the thing is old / original... could be the impeller blades are corroded and not churning the water enough.

Technically all would be maintenance things by now so worth investing in.


Since its old you might want to just swap out the sender for the gauge... could be a faulty seder as well.

 

Sounds like it's infrared thermometer time.

 

Do you mean to tell me that you are regularly letting your engine get that hot?!

Here's a pro-tip: Shut it down before it gets to 240. It sounds like you may have already blown a head gasket or cracked a head.
"Boiling over" does not always happen during an overheating event.
Depending on a variety of factors, an engine can have the gauge pegged completely in the red and still not leak a drop.
I'm sure that you have other issues, too, but it sounds really bad right now.

-Is your radiator clean?
-Are your water pump blades still present?
- Is your thermostat opening?
-Is your lower radiator hose collapsing?
-What's the condition of your coolant? Is your block filled with decades of rust?

So many more things for you to check.

 

most def. thanks for your input.
I have a new water pump on hand, going to swap it out and see what happens. also going to flush the radiator really good. it could be some sludge in it that’s holding back the cooling as well.
car has been running well because of cooler weather here. but warmer weather will be here soon so I need to get it right.

 

The only thing I haven’t changed yes is my water pump, will change it soon.
thermostat is opening and I have new lower and upper hoses.
radiator will and block has been flushed but I’ll have my radiator throughly cleaned at a shop it may be build up that’s stopping water flow.

 

if its that bad you may want to just repalce the rad? Might be worth it