I figured I'd try the new forum and see what kind of response I got. I'm swapping my TBI out in favor of a TPI on my L03, and was wondering if the stock fan will be enough to keep my car cool. I'm also swapping to 081 heads, and a LT1 cam and headers at the same time. Anyone else do this? TIA.

 

I did the same thing. So far It is fine. Thats with a 180* stat.
I just swapped to a 160*, I will let you know if it helped.

oh yeah, I have been running the factory tbi single fan for about 6 years with the 350 TPI.

 

I wonder the same thing with my 305 TPI to 350 TPI switch. It's goin from v-belt to serpentine if that makes any difference.

 

I did the same thing LO3 to L98 and it has been working fine ever since. If I do get into bad traffic (ie 405 at 5:00 for anyone in socal), it does start to hat up a little. This is after an hour in traffic and it only goes up to like 210*. Thats with a 180* stat, edel. water pump and a new radiator.

 

How did you all deal with the fan wiring when doing the swap? Is the fan ecm controlled or off the thermal switch?

 

Since I removed the AC I run a single 14" aftermarket fan, programmed to come on at 160, no problems.

 

I did have some wiring problems when I put the new computer in so as a temporary fix I just put a manual switch under the hood.

 

be careful witht eh 160 degree stat. The computer with the stock chip wont go into closed loop mode. Youll need to get an aftermarket chip or burn your own that alowest eh computer to go into cloed loop mode

 

I'm have a 180 degree stat, and already started prom burning with the L03 so I guess I should be OK. Maybe I'll get lucky and score some fans at Carlisle.

 

My LO3 engine runs hot like 210 with single fanw/AC running so I got a dual fan setup from Thirdgenresource.com.

 

Anyone know why my car would wait until 240 for the fan to come on it really freaks me out every time. could it be that i do not have the right vss after my tpi swap??

 

is that one controlled by the fan switch? TPI's have two fans i think, one that is controlled by the computer and a second that flips on at 240 or so to help cool the engine under high loads and temps. if your using the switch that came with the tpi setup for your one fan than youll need to get a new lowtemp switch.

 

The primary fan control is set via the ecm and the secondary fan is controlled manually by a coolant temp sensor in the passenger head, at least on a TPI car.

I would suggest having a chip burnt or doing it yourself to come on sooner...My Ed Wright chip turns the primary fan on at 176* with a 160* T-stat.

The closed loop operation starts at 154* which is necessary with my T-stat...

HTH,

 

The only fan that comes on is the one at 240

 

Which sounds like the passenger side fan....from the switch in the head. Check the fan relay for the driver's side one and you can manually jumper 12 volts to it to see if it works.

if it works and you can't get it to turn on...wire up the fans manually with a cockpit toggle switch...

Good luck.

 

Running 210 is not really all that hot in the grand scheme of things. 220 is about average for a stock cooling system.
(that's why 220 is in the middle of the gauge)

Here's my setup:
New, stock style aluminum radiator, Stewart StageII aluminum water pump, Stewart-modified 195 thermostat. Stock Single Fan 305TPI

At the autocross yesterday, it was 92, and the surface temperature on the concrete was 115. On a very fast course (lots of WOT), the water temp was 215 after four runs.
With the origninal cooling system, I would usually be near 240 after two runs.

The new rad was the last to go on and it made the biggest difference. The old one was full of deposits, so I probably lost a lot of cooling capacity. Heck, it's $100 and takes 45 minutes to swap (with a system flush)

 

Just because you are swapping the injection setup, doesnt mean you're going to overheat. Part of the allure of the G92 cars was the fact that they had dual fans, single fans were installed on auto TPI cars. You don't need dual fans on a TPI 305 to sum it up....

 

Depends on what your motor is pushing for HP. The higher the HP, generally the higher the heat. Headers, big heads, big cam, generally create heat.

IN the summer (here in boston mind you, which is usually under 80) I run dual fans constantly and I cruise around 180`.. If I turn the fans off, I hit 230 very very fast.. Not good for oil.

I know a lot of guys say the single fan is OK, but if your building a high hp application (you sai dyour chnaging heads + cam, headers) I recommend you go with the dual.

I also recommend if your in there, you rip out the factory wiring and wire a hayden adjustable switch so you can program the fans to come on at like 180 or something.. That works good for me in the colder months, but in the summer I just leave 'em on constant.

-- Joe

 

Bzzz, wrong answer. The TPI cars in '85 and maybe '86 had the single fan, while all of the TPI cars (305 with auto or manual and 350/auto) from '87-92 had the dual fans. My '87 IROC came with a 305/auto and has dual fans.

 

Ok but that wasnt the point I was trying to get across anyway......

 

I would think you'll be fine. Though I would change the temp at which the fans turns on, that stock 220* setting is a bit high to me.

 

Thanks for the replys. I found a pair of TA fans on ebay for 18 bucks, so I'm going to err on the side of caution and go with the dual setup. I know my combo won't be a screamer with the 081 heads and LT1 cam, but we get our share of 100+ degree weather. One more question, how does the ajustable fan switch work? Is it a variable resistor in line with a coolant sensor? I'd like to make one if it's possible.

 

I think the switch grounds at 220, and thats it..

Lemme know what you come up with.

-- Joe

 

On TBI units the single fan is not ECM controlled. It is driven by the fan switch on the passenger side of the block. The fan switch drives the fan relay without any assistance from the ECM. The only other factor is the AC pressure switch, it also connects to the fan relay to turn on the fan when head pressure is achieved. On TPI models the primary fan in controlled by the ECM through the primary fan relay. The secondary fan on a TPI essentially works the same as the single fan setup on the TBI models. According to a rep I spoke with from GM the reason for using the ECM on TPI cars was that they wanted more precise control of the engine operating range. They wanted these vehicles to run in the 200 deg range for engine efficiency, and fuel economy. One can gather efficiency also equals emissions. What is more important is to keep the engine operating in a narrow range. Large swings in temp caused by lower temp stats and fans on all the time is actually counterproductive. My neighbor is a design engineer for a company that makes aircraft refuelers. These engines run 24/7 so efficiency is a major factor. They use the engine to also run the pumps and they have found hotter running engines run better and are more fuel efficient. Several companies are looking into engines that will run in the 250 range. Material limitation problems once they are solved will increase engine efficiency dramatically. A TG will run best at 195 with a properly operating cooling system. The biggest problems with the TG's is reliability of the fan relays. The newer GM replacements are redesigned and are much more reliable. I tried many setups on mine and it is running the best at stock operating temp. I know this will generate a lot of hate and discontent but I have researched this in depth over the last year or so and every expert I have spoken with has told me the same thing. As a final thought I would be concerned about the quality of the oil then whether or not it runs at 180 or 195. Synthetic is good insurance for the engine

 

I know that the primary fan is ecm controlled but what tells the ecm what temp the engine is at. its the Coolant temp sensor right?? cause my primary fan is not coming on at all just the secondary and i tested the relay and its ok and i also bypassed the relay and i know it cant be from the relay to the fan cause thats ok too. so what could it be? coolant temp sensor?? i mean its only 12 bucks so i should probably get one anyways. right but any other suggestions are duelly noted.

 

On dual fan setups the ECM controls the primary fan from input from the coolant temp sensor and the VSS. Also AC head pressure controls the primary fan operation when in AC mode. There are two heavy wires on the fan relay plug and two lighter guage ones. You can jump the two heavier ones and the fan should come on, if it doesn't the the 12 volts is missing or the fan went kaputt. There is a driver in the ECM to drive the fan relay, but I have never seen one fail unless someone puts a jumper in incorrectly. I would not waste money on a sensor, you would have other problems if it failed and it would be throwing codes. The relays are notorious for being intermittent. Just swap the primary and secondary relays and see what happens as they are the same part#. LOL

 

I was under the impression that the sensor on the right side controled the fans (mine come on at the same time -- at 230),
the sensor on the left side is for the ECM, as well as the one in the very front?

-- Joe