TheMagikMan

Does anyone have a bone stock bin for a 1986 Trans Am or IROC with a TPI, 700r4, and air conditioning? I seem to be having an airflow/tune issue in hot weather with the A/C on, and I know my cooling system should be MORE than adequate. I have a cold case radiator with twin 180W fans and a proper shroud. I'm looking for any differences in my tune with a stock one that might cause that issue. I did at one point copy over almost EVERYTHING save my timing tables and fuel curve from an ARAP Corvette bin. Could that have something to do with it? I have updated every part of the cooling system and verified fans are turning on when they should be, but with the hood closed it still seems like it's overworked. I suppose I could pull the bin off my stock chip if I can find that though. If you already have it or have suggestions for parameters to look out for, please let me know.

Tuned Performance

iTrader: (92)

http://www.gearhead-efi.com/Fuel-Inj...Information-32

TheMagikMan

I forgot to mention that my car is running $6E. Are there any $6E differences I need to make sure I carry over from $32 that could affect temperatures?

Tuned Performance

iTrader: (92)

Did you change fan on/offs a/c on / off ?

TheMagikMan

Yes I did. Like I said, fans come on when they should, just doesn't pull the temp down unless AC is off

Tuned Performance

iTrader: (92)

there are just idle adder and fan on/offs with ac. If temperature is drastically increasing with ac load is an airflow or cooling system issue. Nothing with tuning

TheMagikMan

I don't understand what's going wrong then. I have upgraded the radiator, shroud, and the fans beyond even what cold case ships. I don't know what to do at this point. It's just a TPI 350 with an edelbrock base and SLP runners. I shouldn't be making enough heat to overwhelm it at all but it just heats in traffic with the AC on. I have a transmission cooler at the front of the stack but I can't imagine that adds enough heat to overwhelm the system

ULTM8Z

How are your fans triggered? Both come on simultaneously via the ECM? Or is one triggered by the coolant switch in the cylinder head?

I'm browsing through 6E and there are several parameters that affect fan turn on temps... and they depend on whether the AC is on or not. Have you adjusted these?

Fan 1 turn on with AC on
Fan 1 turn off with AC on
Fan 1 turn on with AC off
Fan 1 turn off with AC off

The temps appear to be the same whether AC is on or off though...

Then there's this one...

MPH for Fan 1 turn on if A/C on Set to 11 mph. Maybe trying setting to 0?

Could also be that at hotter temps the car is starting to run leaner... and a leaner engine will probably run hotter, so you get into a vicious cycle.

On the Rich/Lean offset vs coolant temp, you might try zeroing out the values there...

TheMagikMan

I have adjusted those parameters. The rich/lean offset is something I have NOT looked at. I'll look at that and compare it to a stock 89 BIN to see if it's changed.

Edit: It appears that I have adjusted that lower to match the thermostat.

ULTM8Z

One thing that's probably highly unlikely, but maybe worth checking...

Is your thermostat opening all the way.

I had discovered a quirk in the Miniram where the front water passage was too shallow to allow the thermostat to open all the way, which forced me to run a spacer under the water neck. 99.999% sure that was strictly a Miniram thing. Might be worth checking none-the-less.

Is the fan shroud sealed well against the radiator?

What's your water/antifreeze ratio?

86 is pre-serpentine... you're sure you don't have a reverse rotation pump inadvertently?

TheMagikMan

water/antifreeze is 50/50, fan shroud is sealed very well, and I have the correct rotation pump. Cools just fine rolling down the highway

ULTM8Z

Maybe the fans aren't powerful enough? Not sure how yours compare to say, LS1 fans.

TheMagikMan

I used to have LS1 fans before this radiator and they wouldn't fit (rad is too thick for stock shroud) so these are what I bought. Advertised at 2700cfm+ each and I have 2 of them. I would imagine that's better than stock LS1 fans

https://www.americanvolt.com/collect...sible-air-flow

ULTM8Z

Just some other dumb questions to cover the basics...

1. Fans are turning in the right direction?

2. Are the blades reversible? Possible they're installed backwards?

3. Wiring to the fans is robust enough to not cause an excessive voltage drop? Low voltage at the fans will cause them to spin slower.

4. What temperature is it hitting that you're worried about?

5. What thermostat are you running?

6. I'm assuming you're running a R4 compressor. I remember that thing was a power hog when i was running it. One of the reasons I switched to a Sanden. It would also cause the car to run much hotter due to that fact. If your compressor is as bad or worse than mine was, them it's just an excessive load on the engine. With my Sanden, you can't even tell the thing is on in terms of power consumption. Engine runs about 5-10 deg warmer, but that's normal. So instead of 180F, it's about 190F (even on a 95F day).

dabomb6608

iTrader: (3)

I am going to go out on a limb here and say those cheap 180W 13 amp fans probably aren't producing the advertised 2700cfm per fan. A Spal 13" pulls 23 amps and is an advertised 1777 CFM. https://www.summitracing.com/parts/s...8aAoliEALw_wcB 14 ga wiring is pretty laughable for a cooling fan too.

What is your shroud setup? Another important question is what are your low/high AC pressures at? A struggling AC system can put some heat to the condenser.

ULTM8Z

In free air they might be moving 2700 CFM.

But what counts on any cooling fan is pulling power across a static pressure drop. It could be that they simply can't move much air when presented with the restriction of a radiator and condenser. The amount of air they move may be satisfactory for no A/C, but once you add the heat from the condenser, the air velocity through the radiator is no longer sufficient.

dabomb6608

iTrader: (3)

Yep. Free air vs resistance combined with tiny 13 amp motors is likely pulling very little air across the radiator/condenser combo. He needs to upgrade to some of the more tried & trued methods. Taurus Fan, Mark VIII Fan, etc. Also needs to make sure the sides are all sealed off between the rad/cond. Air will travel the path of least resistance, so anywhere it can travel that isn't through the two large restrictions is the path it is going to take. This is why people constantly harp about fan shroud designs and sealing off the sides. Factor all of that with missing air dams and it is no wonder we constantly see overheat posts. It certainly doesn't help that these cars ran hot from factory, but we are in the DIY Prom forum where that is easily avoidable.

ULTM8Z

I'm running a two speed Taurus fan. Now thatthing moves some air... lol.

When I first installed it, I made the error of putting only a 40amp relay on the high speed side. Damn relay literally caught on fire from the current this thing evidently pulls. Ended up with a Bosch 75 amp relay on both the low and high speeds and it's been running great ever since.

May also need to upgrade the alternator if using one of those fans. My old CS130 couldn't handle it when the high-speed side came on and all the other accessories were going. Voltage at idle would drop just a hair over 12V. AD244 solved that problem. Funny how things snowball in this hobby... lol

dabomb6608

iTrader: (3)

I've currently got the two speed Mark VIII. Previously had a Taurus fan that eventually quit on me. You are 100% correct, they move air some for sure. And they are definitely amp thirsty! Heavy duty wiring, relays and fuses are a must. I run the Volvo two speed controller with power through a big amp relay like yours. I want to say I used 8awg wiring for the power/ground feeds to fan. My poor CS130 definitely struggles. During the day with no HVAC running or any other major power drains (lights) I see about 12.8V at idle and 13V cruising. Cold start it sits at 13.8V.

That is mainly why I plan on moving to a brushless fan setup when I rehab my AC system. Like mentioned in the thread I started the other day over in cooling forum. I will upgrade alternators at that time if the brushless fan is still to much of a amperage drain. I am really thinking it won't be however with its variable rate ability and the efficiencies seen with brushless motors.

For the OP I will add this. Years ago when I first slapped AC on this car I was running the Taurus fan at the time. Fast forward some months and I was having cooling issues. Mainly at low speeds, highway speeds it would maintain decent temps. I chased it for longer than I should have. Even replacing my factory radiator to a larger all aluminium unit. The weak/failing taurus fan was the problem. New fans or not do not discount how much weak airflow can contribute to an otherwise functioning cooling system.

ULTM8Z

Yeah, you shouldn't need huge radiator on a street car with a relative mild engine. I'm running a "Autozone" stock style plastic-tank aluminum radiator and a stock style water pump. Cools my 383 just fine in any weather, A/C on or off.

The OP is saying the car cools ok at speed, so that's definitely pointing to inadequate fans. If the all aluminum radiator is too thick, might consider selling it and getting a stock style thinner one, then either LS1 twin fans or a Taurus/MarkVII two speed.