Hey all,

Just upgraded to dual TPI fans from a single fan and added a built transmission with 2800 Vigilante stall converter. I mounted a trans cooler in front of the radiator on the passenger side.

The routing is from the transmisson, into the radiator, then to the trans cooler and back to the transmission.

180 Thermostat
204* Temp switch for primary fan
212* switch for secondary fan.
Stock Radiator.
New coolant, flushed and burped.
Motor is a 355, CC Qjet
Built 700R4 (Road race kit from Pro-Built)

With an IR temp gun, my temperatures at the water neck read 215-219* when the interior gauge reads 225-230.

I took the car out for a 30 mile run on the interstate and my temp never dropped below 220 (dead center) on the gauge, so 210* or so based on what the IR gun told me. this is with the AC on. In town it floats between the 220 mark and the 240 tick but doesn't go over the 240 mark.

Before this, running on the interstate, the temp would never get over the 220 mark on the gauge. In town it would float over 220 until the fan kicked on then drop back down under it. So say, 190 or so (It was clearly below the 220 mark on the gauge).

Is this much of a temperature jump expected after installing a high-stall converter and built transmission (20* or so)? i mean I understand the high stall will create more heat but I didn't expect to see such a radical change on the actual temp gauge.

Any input is gladly welcome. Thanks!

 

I don't know the answer to your exact question but because of the higher stall I would drop the fan switch temperatures a little more to take full advantage of the 180* thermostat. Maybe a 190*"on" with a 200* "on" as backup.

 

Is it a lockup style converter??? If the converter is locking up properly at cruising speeds it shouldn't be making any more heat than stock. Did you leave atleast a 1/2-1" gap between the radiator and cooler?

 

Matt-if you use (2) 212/202 GM style temp switches one in the head, the other in your intake, even though they have the same temp range, they will be triggered at 2 different intervals since the head generates about 15-20 degrees more heat than the intake area. So the head switch acts as low speed trigger for the fan setup and the same temp switch in the intake acts as the medium temp switch. Might be worth trying. I know you want to retain the TPI style fans but you may be getting to the point where due to limited CFM volume, they may need to run a lot just to keep temps marginal. I think we touched on this a little bit over the phone while you were working on your setup.

 

While I agree on the shrouded LT1 fans being better, the 87 Firebird I set up with a 375-400 hp 355 with a/c running stays nice and cool with the single LG4 fan. Runs about 178-182*F with my IR gun on the thermotat housing with a 160*F thermostat and 180*F fan switch.

 

Lower fan switches won't make a difference if, as it seems, both are running with temps at around 220.

I would not expect a running temp difference just from the Trans swap, at least not a noticeable one. Look for something else that may have changed. 190-200 should be an easily obtained normal running temp.

 

Which is the best reading to go by for the true temp?

Water neck? Upper radiator hose or radiator cap?

 

double post...

 

Yes, its a lockup style converter.

There is no gap, I'm using the x-brace in front of the AC condensor to hold it right to the condensor.

I'm no good with fab work so I try and use what's available to hold things in place.

 

there is a little space since I used the cushioned corners that came in the cooler package but otherwise it's pushed right up against the condenser.

 

He is running one of my 3-speed resistor fan harnesses-the setup is not exactly stock....both fans ramp gradually from low-medium-high.

 

I ran around a bit this morning with no AC on, temp is already high 80's and should be near 100 by mid-afternoon. With no AC, the temp stays pretty steady at right at 220 mark on the gauge.

IR gun on the water pump inlet says 205, on the water neck 2010. It's chrome though so i don't know how true of a reading it's giving me due to laser scatter.

 

I'm tempted just connect the Hi-speed bypass so it kicks on at high-speed and runs that speed all the time to see if that has any effect.

The whole reason i swapped over in the first place was because with the single fan I had factory, it would just over heat gradually with the AC on eventually going deep into the red. At least with this dual fan system running, it seem to level out around 230-240 on the gauge.

I need to take it up into the mountains and see how it does on a 5000 foot over 2 mile incline... lol Its a beautiful switchback road but it made my 06 avalanche steam from the motor and that cooling system runs perfect. haha

 

but at 220 they should both be running full on.

so it ran hot before the Trans swap? At least with ac on?

 

Yes, in a nut shell.


Before with my single fan set up, prior to the transmission swap, with AC on in town or stop and go traffic, the car would gradually heat up and go deep into the red and puke out my overflow. On the highway cruising over 45 it would cool down to 220 and sit there pretty steady.

With no ac on, the car would heat up to 220-230, then settle back down and float 180-220 in town. On the highway it would sit just under the 220 mark and hold steady.

Now, with the AC on in traffic it floats 230-240 but I never saw it go over the 240 tick mark on the gauge.

On the highway, with the AC running, it sat right around 230 but never came back to the 220 mark (Small sample, 30 mile round trip last night on the highway).

With the AC off this morning, it seemed to hover right at 220 and while it went to the right of the white 220 mark, it did not go over while driving around town. I'll do some more driving today with no Ac on in town and hopefully get a larger sample size.

I guess I'm trying to figure out if this is the "new" normal or if I have something a little messed up.

In 14 days I am moving and this this is going on a 1400 mile trip through the mountains and great plains. It's going to be hot and if my wife drives it instead of the truck with trailer, she will be using the AC so i need to make sure it's as good as possible before we go.

 

I have done 7-10 miles of near constant 6-7% grade with switch backs pulling 7,000# with my 1997 Express and the old 350 was near WOT for alot of it. Never even came close to overheating. I am sure the 1-ton 454 G3500 radiator, engine oil cooler, and duramax fan blade have alot to do with that though. Although I do have a 25% underdrive crank pulley on it.

 

Sounds like you need to retrofit over a LT1 fan assembly into the car. The shroud assembly makes a huge difference. I also seem to remember the LT1 fan motors having higher wattage motors.

Also does your car still have the factory air dam under it? That has a very useful purpose and can lower the engine temperature 20*+ on the highway at highway speeds by directing air up into the radiator and creating a negative pressure area behind it to help pull the hot air out of the radiator and engine compartment.

 

I was staying away from LT1 or LS1 fan shrouds due to the modification steps and my time frame. Also, all of my main tools were packed by the mover this week and i moved out of my house into a neighbors until we leave.

the Air dam is in place and is functional/not cracked or broken.

 

I can relate! At 60 mph you shouldn't really be needing the fans anyway.

Is the gap between the condensor and radiator clean of debris?

Have you hosed out the condenser/radiator with a patio wash nozzle?? (A pressure washer has too much pressure and will bend the fins). I was mine out several times a year in warmer weather to keep it clear of bugs, leafs, rocks, etc that would block airflow.

 

it's clean, made sure of that when I installed the trans cooler infront of the condenser. I suppose it wouldn't hurt it too much.

 

The Vigilante shouldn't create any more heat going down the highway. Once it's locked up (typically about 40 mph or faster), it creates the same amount of heat as a stock converter.

80° weather shouldn't have the car running at 220° in city or highway. I run 220° when I'm stuck in 5PM rush hour gridlock when it's over 90° and humid on top of that.

Adding a cooler when doing a converter is a good idea. The trouble with mounting it directly onto the condenser is that the heat from the transmission cooler heats up the condenser. And the heat from the condenser heats up the transmission cooler. (Hence why a gap is recommended). The A/C performance goes down when this happens (condenser is running hotter) and all of this heat has to be taking out by the radiator.

TPI dual fans are normally off when driving down the highway. Once you get past 45 mph, they turn off. But you have a different setup it seems.

I would look into the radiator being the culprit. Try taking the IR gun and aiming it all over the radiator when the engine is hot and turned off. If you see drastic differences in any area, then you've got a plugged radiator. Could be a water pump too.

 

I pulled a ~3,000 lb tandem axle trailer with a 5,000 quad cab Dodge Dakota for about 300 miles Friday afternoon in 95*F weather. Pulled it with my 350 Vortec powered Express van. The first time I stopped for gas after having been running 65-70 mph down the highway for 4 hours straight at about 2,600-3,000 rpm, I pulled out my IR gun. My HP Tuners datalog said the engine temps were 190*F at the thermostat housing, running a 180*F thermostat and a 25% underdrive pulley on the crank. The auxiliary pusher electric fan was OFF on the trans cooler. Hot side radiator tank was ~185*F. The engine oil cooler line coming out of the engine was 210*F. The lower oil line going back to the engine was ~190*F. The cool side of the radiator was ~130*F. The transmission fluid was coming in at 170*F. Leaving the lower radiator at 145*F and entering the Auxiliary cooler at 138*F and leaving that cooler at 118*F. The condensor was 136*F on the compressor side and about 105*F where it exits. But the shock was the fact I need to add the factory Express power steering cooler. The reservoir and hydroboost was at 160*F!! I also shot the trans pan and the rear differential cover. Good thing I am going to a larger differential, it was also over 200*F. The transmission pans was a nice 140*F.